Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Generic ring buffer |
| 3 | * |
| 4 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> |
| 5 | */ |
Steven Rostedt (Red Hat) | af658dc | 2015-04-29 14:36:05 -0400 | [diff] [blame] | 6 | #include <linux/trace_events.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 7 | #include <linux/ring_buffer.h> |
Ingo Molnar | 14131f2 | 2009-02-26 18:47:11 +0100 | [diff] [blame] | 8 | #include <linux/trace_clock.h> |
Steven Rostedt | 0b07436 | 2013-01-22 16:58:30 -0500 | [diff] [blame] | 9 | #include <linux/trace_seq.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 10 | #include <linux/spinlock.h> |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 11 | #include <linux/irq_work.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 12 | #include <linux/uaccess.h> |
Steven Rostedt | a81bd80 | 2009-02-06 01:45:16 -0500 | [diff] [blame] | 13 | #include <linux/hardirq.h> |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 14 | #include <linux/kthread.h> /* for self test */ |
Vegard Nossum | 1744a21 | 2009-02-28 08:29:44 +0100 | [diff] [blame] | 15 | #include <linux/kmemcheck.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 16 | #include <linux/module.h> |
| 17 | #include <linux/percpu.h> |
| 18 | #include <linux/mutex.h> |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 19 | #include <linux/delay.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 20 | #include <linux/slab.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 21 | #include <linux/init.h> |
| 22 | #include <linux/hash.h> |
| 23 | #include <linux/list.h> |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 24 | #include <linux/cpu.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 25 | |
Christoph Lameter | 7961576 | 2010-01-05 15:34:50 +0900 | [diff] [blame] | 26 | #include <asm/local.h> |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 27 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 28 | static void update_pages_handler(struct work_struct *work); |
| 29 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 30 | /* |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 31 | * The ring buffer header is special. We must manually up keep it. |
| 32 | */ |
| 33 | int ring_buffer_print_entry_header(struct trace_seq *s) |
| 34 | { |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 35 | trace_seq_puts(s, "# compressed entry header\n"); |
| 36 | trace_seq_puts(s, "\ttype_len : 5 bits\n"); |
| 37 | trace_seq_puts(s, "\ttime_delta : 27 bits\n"); |
| 38 | trace_seq_puts(s, "\tarray : 32 bits\n"); |
| 39 | trace_seq_putc(s, '\n'); |
| 40 | trace_seq_printf(s, "\tpadding : type == %d\n", |
| 41 | RINGBUF_TYPE_PADDING); |
| 42 | trace_seq_printf(s, "\ttime_extend : type == %d\n", |
| 43 | RINGBUF_TYPE_TIME_EXTEND); |
| 44 | trace_seq_printf(s, "\tdata max type_len == %d\n", |
| 45 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 46 | |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 47 | return !trace_seq_has_overflowed(s); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 48 | } |
| 49 | |
| 50 | /* |
Steven Rostedt | 5cc9854 | 2009-03-12 22:24:17 -0400 | [diff] [blame] | 51 | * The ring buffer is made up of a list of pages. A separate list of pages is |
| 52 | * allocated for each CPU. A writer may only write to a buffer that is |
| 53 | * associated with the CPU it is currently executing on. A reader may read |
| 54 | * from any per cpu buffer. |
| 55 | * |
| 56 | * The reader is special. For each per cpu buffer, the reader has its own |
| 57 | * reader page. When a reader has read the entire reader page, this reader |
| 58 | * page is swapped with another page in the ring buffer. |
| 59 | * |
| 60 | * Now, as long as the writer is off the reader page, the reader can do what |
| 61 | * ever it wants with that page. The writer will never write to that page |
| 62 | * again (as long as it is out of the ring buffer). |
| 63 | * |
| 64 | * Here's some silly ASCII art. |
| 65 | * |
| 66 | * +------+ |
| 67 | * |reader| RING BUFFER |
| 68 | * |page | |
| 69 | * +------+ +---+ +---+ +---+ |
| 70 | * | |-->| |-->| | |
| 71 | * +---+ +---+ +---+ |
| 72 | * ^ | |
| 73 | * | | |
| 74 | * +---------------+ |
| 75 | * |
| 76 | * |
| 77 | * +------+ |
| 78 | * |reader| RING BUFFER |
| 79 | * |page |------------------v |
| 80 | * +------+ +---+ +---+ +---+ |
| 81 | * | |-->| |-->| | |
| 82 | * +---+ +---+ +---+ |
| 83 | * ^ | |
| 84 | * | | |
| 85 | * +---------------+ |
| 86 | * |
| 87 | * |
| 88 | * +------+ |
| 89 | * |reader| RING BUFFER |
| 90 | * |page |------------------v |
| 91 | * +------+ +---+ +---+ +---+ |
| 92 | * ^ | |-->| |-->| | |
| 93 | * | +---+ +---+ +---+ |
| 94 | * | | |
| 95 | * | | |
| 96 | * +------------------------------+ |
| 97 | * |
| 98 | * |
| 99 | * +------+ |
| 100 | * |buffer| RING BUFFER |
| 101 | * |page |------------------v |
| 102 | * +------+ +---+ +---+ +---+ |
| 103 | * ^ | | | |-->| | |
| 104 | * | New +---+ +---+ +---+ |
| 105 | * | Reader------^ | |
| 106 | * | page | |
| 107 | * +------------------------------+ |
| 108 | * |
| 109 | * |
| 110 | * After we make this swap, the reader can hand this page off to the splice |
| 111 | * code and be done with it. It can even allocate a new page if it needs to |
| 112 | * and swap that into the ring buffer. |
| 113 | * |
| 114 | * We will be using cmpxchg soon to make all this lockless. |
| 115 | * |
| 116 | */ |
| 117 | |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 118 | /* Used for individual buffers (after the counter) */ |
| 119 | #define RB_BUFFER_OFF (1 << 20) |
| 120 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 121 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
| 122 | |
Steven Rostedt | e3d6bf0 | 2009-03-03 13:53:07 -0500 | [diff] [blame] | 123 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 124 | #define RB_ALIGNMENT 4U |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 125 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 126 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 127 | |
James Hogan | 649508f | 2012-05-30 12:11:19 +0100 | [diff] [blame] | 128 | #ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS |
Steven Rostedt | 2271048 | 2010-03-18 17:54:19 -0400 | [diff] [blame] | 129 | # define RB_FORCE_8BYTE_ALIGNMENT 0 |
| 130 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT |
| 131 | #else |
| 132 | # define RB_FORCE_8BYTE_ALIGNMENT 1 |
| 133 | # define RB_ARCH_ALIGNMENT 8U |
| 134 | #endif |
| 135 | |
James Hogan | 649508f | 2012-05-30 12:11:19 +0100 | [diff] [blame] | 136 | #define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) |
| 137 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 138 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
| 139 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 140 | |
| 141 | enum { |
| 142 | RB_LEN_TIME_EXTEND = 8, |
| 143 | RB_LEN_TIME_STAMP = 16, |
| 144 | }; |
| 145 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 146 | #define skip_time_extend(event) \ |
| 147 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) |
| 148 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 149 | static inline int rb_null_event(struct ring_buffer_event *event) |
| 150 | { |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 151 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 152 | } |
| 153 | |
| 154 | static void rb_event_set_padding(struct ring_buffer_event *event) |
| 155 | { |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 156 | /* padding has a NULL time_delta */ |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 157 | event->type_len = RINGBUF_TYPE_PADDING; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 158 | event->time_delta = 0; |
| 159 | } |
| 160 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 161 | static unsigned |
| 162 | rb_event_data_length(struct ring_buffer_event *event) |
| 163 | { |
| 164 | unsigned length; |
| 165 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 166 | if (event->type_len) |
| 167 | length = event->type_len * RB_ALIGNMENT; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 168 | else |
| 169 | length = event->array[0]; |
| 170 | return length + RB_EVNT_HDR_SIZE; |
| 171 | } |
| 172 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 173 | /* |
| 174 | * Return the length of the given event. Will return |
| 175 | * the length of the time extend if the event is a |
| 176 | * time extend. |
| 177 | */ |
| 178 | static inline unsigned |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 179 | rb_event_length(struct ring_buffer_event *event) |
| 180 | { |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 181 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 182 | case RINGBUF_TYPE_PADDING: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 183 | if (rb_null_event(event)) |
| 184 | /* undefined */ |
| 185 | return -1; |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 186 | return event->array[0] + RB_EVNT_HDR_SIZE; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 187 | |
| 188 | case RINGBUF_TYPE_TIME_EXTEND: |
| 189 | return RB_LEN_TIME_EXTEND; |
| 190 | |
| 191 | case RINGBUF_TYPE_TIME_STAMP: |
| 192 | return RB_LEN_TIME_STAMP; |
| 193 | |
| 194 | case RINGBUF_TYPE_DATA: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 195 | return rb_event_data_length(event); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 196 | default: |
| 197 | BUG(); |
| 198 | } |
| 199 | /* not hit */ |
| 200 | return 0; |
| 201 | } |
| 202 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 203 | /* |
| 204 | * Return total length of time extend and data, |
| 205 | * or just the event length for all other events. |
| 206 | */ |
| 207 | static inline unsigned |
| 208 | rb_event_ts_length(struct ring_buffer_event *event) |
| 209 | { |
| 210 | unsigned len = 0; |
| 211 | |
| 212 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { |
| 213 | /* time extends include the data event after it */ |
| 214 | len = RB_LEN_TIME_EXTEND; |
| 215 | event = skip_time_extend(event); |
| 216 | } |
| 217 | return len + rb_event_length(event); |
| 218 | } |
| 219 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 220 | /** |
| 221 | * ring_buffer_event_length - return the length of the event |
| 222 | * @event: the event to get the length of |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 223 | * |
| 224 | * Returns the size of the data load of a data event. |
| 225 | * If the event is something other than a data event, it |
| 226 | * returns the size of the event itself. With the exception |
| 227 | * of a TIME EXTEND, where it still returns the size of the |
| 228 | * data load of the data event after it. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 229 | */ |
| 230 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) |
| 231 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 232 | unsigned length; |
| 233 | |
| 234 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
| 235 | event = skip_time_extend(event); |
| 236 | |
| 237 | length = rb_event_length(event); |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 238 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
Robert Richter | 465634a | 2009-01-07 15:32:11 +0100 | [diff] [blame] | 239 | return length; |
| 240 | length -= RB_EVNT_HDR_SIZE; |
| 241 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) |
| 242 | length -= sizeof(event->array[0]); |
| 243 | return length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 244 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 245 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 246 | |
| 247 | /* inline for ring buffer fast paths */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 248 | static void * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 249 | rb_event_data(struct ring_buffer_event *event) |
| 250 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 251 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
| 252 | event = skip_time_extend(event); |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 253 | BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 254 | /* If length is in len field, then array[0] has the data */ |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 255 | if (event->type_len) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 256 | return (void *)&event->array[0]; |
| 257 | /* Otherwise length is in array[0] and array[1] has the data */ |
| 258 | return (void *)&event->array[1]; |
| 259 | } |
| 260 | |
| 261 | /** |
| 262 | * ring_buffer_event_data - return the data of the event |
| 263 | * @event: the event to get the data from |
| 264 | */ |
| 265 | void *ring_buffer_event_data(struct ring_buffer_event *event) |
| 266 | { |
| 267 | return rb_event_data(event); |
| 268 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 269 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 270 | |
| 271 | #define for_each_buffer_cpu(buffer, cpu) \ |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 272 | for_each_cpu(cpu, buffer->cpumask) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 273 | |
| 274 | #define TS_SHIFT 27 |
| 275 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) |
| 276 | #define TS_DELTA_TEST (~TS_MASK) |
| 277 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 278 | /* Flag when events were overwritten */ |
| 279 | #define RB_MISSED_EVENTS (1 << 31) |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 280 | /* Missed count stored at end */ |
| 281 | #define RB_MISSED_STORED (1 << 30) |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 282 | |
Steven Rostedt (VMware) | 2e0d458 | 2017-12-22 20:32:35 -0500 | [diff] [blame] | 283 | #define RB_MISSED_FLAGS (RB_MISSED_EVENTS|RB_MISSED_STORED) |
| 284 | |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 285 | struct buffer_data_page { |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 286 | u64 time_stamp; /* page time stamp */ |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 287 | local_t commit; /* write committed index */ |
James Hogan | 649508f | 2012-05-30 12:11:19 +0100 | [diff] [blame] | 288 | unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 289 | }; |
| 290 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 291 | /* |
| 292 | * Note, the buffer_page list must be first. The buffer pages |
| 293 | * are allocated in cache lines, which means that each buffer |
| 294 | * page will be at the beginning of a cache line, and thus |
| 295 | * the least significant bits will be zero. We use this to |
| 296 | * add flags in the list struct pointers, to make the ring buffer |
| 297 | * lockless. |
| 298 | */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 299 | struct buffer_page { |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 300 | struct list_head list; /* list of buffer pages */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 301 | local_t write; /* index for next write */ |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 302 | unsigned read; /* index for next read */ |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 303 | local_t entries; /* entries on this page */ |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 304 | unsigned long real_end; /* real end of data */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 305 | struct buffer_data_page *page; /* Actual data page */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 306 | }; |
| 307 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 308 | /* |
| 309 | * The buffer page counters, write and entries, must be reset |
| 310 | * atomically when crossing page boundaries. To synchronize this |
| 311 | * update, two counters are inserted into the number. One is |
| 312 | * the actual counter for the write position or count on the page. |
| 313 | * |
| 314 | * The other is a counter of updaters. Before an update happens |
| 315 | * the update partition of the counter is incremented. This will |
| 316 | * allow the updater to update the counter atomically. |
| 317 | * |
| 318 | * The counter is 20 bits, and the state data is 12. |
| 319 | */ |
| 320 | #define RB_WRITE_MASK 0xfffff |
| 321 | #define RB_WRITE_INTCNT (1 << 20) |
| 322 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 323 | static void rb_init_page(struct buffer_data_page *bpage) |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 324 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 325 | local_set(&bpage->commit, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 326 | } |
| 327 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 328 | /** |
| 329 | * ring_buffer_page_len - the size of data on the page. |
| 330 | * @page: The page to read |
| 331 | * |
| 332 | * Returns the amount of data on the page, including buffer page header. |
| 333 | */ |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 334 | size_t ring_buffer_page_len(void *page) |
| 335 | { |
Steven Rostedt (VMware) | 2e0d458 | 2017-12-22 20:32:35 -0500 | [diff] [blame] | 336 | struct buffer_data_page *bpage = page; |
| 337 | |
| 338 | return (local_read(&bpage->commit) & ~RB_MISSED_FLAGS) |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 339 | + BUF_PAGE_HDR_SIZE; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 340 | } |
| 341 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 342 | /* |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 343 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing |
| 344 | * this issue out. |
| 345 | */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 346 | static void free_buffer_page(struct buffer_page *bpage) |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 347 | { |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 348 | free_page((unsigned long)bpage->page); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 349 | kfree(bpage); |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 350 | } |
| 351 | |
| 352 | /* |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 353 | * We need to fit the time_stamp delta into 27 bits. |
| 354 | */ |
| 355 | static inline int test_time_stamp(u64 delta) |
| 356 | { |
| 357 | if (delta & TS_DELTA_TEST) |
| 358 | return 1; |
| 359 | return 0; |
| 360 | } |
| 361 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 362 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 363 | |
Steven Rostedt | be957c4 | 2009-05-11 14:42:53 -0400 | [diff] [blame] | 364 | /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ |
| 365 | #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) |
| 366 | |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 367 | int ring_buffer_print_page_header(struct trace_seq *s) |
| 368 | { |
| 369 | struct buffer_data_page field; |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 370 | |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 371 | trace_seq_printf(s, "\tfield: u64 timestamp;\t" |
| 372 | "offset:0;\tsize:%u;\tsigned:%u;\n", |
| 373 | (unsigned int)sizeof(field.time_stamp), |
| 374 | (unsigned int)is_signed_type(u64)); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 375 | |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 376 | trace_seq_printf(s, "\tfield: local_t commit;\t" |
| 377 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
| 378 | (unsigned int)offsetof(typeof(field), commit), |
| 379 | (unsigned int)sizeof(field.commit), |
| 380 | (unsigned int)is_signed_type(long)); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 381 | |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 382 | trace_seq_printf(s, "\tfield: int overwrite;\t" |
| 383 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
| 384 | (unsigned int)offsetof(typeof(field), commit), |
| 385 | 1, |
| 386 | (unsigned int)is_signed_type(long)); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 387 | |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 388 | trace_seq_printf(s, "\tfield: char data;\t" |
| 389 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
| 390 | (unsigned int)offsetof(typeof(field), data), |
| 391 | (unsigned int)BUF_PAGE_SIZE, |
| 392 | (unsigned int)is_signed_type(char)); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 393 | |
Steven Rostedt (Red Hat) | c0cd93a | 2014-11-12 11:49:00 -0500 | [diff] [blame] | 394 | return !trace_seq_has_overflowed(s); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 395 | } |
| 396 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 397 | struct rb_irq_work { |
| 398 | struct irq_work work; |
| 399 | wait_queue_head_t waiters; |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 400 | wait_queue_head_t full_waiters; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 401 | bool waiters_pending; |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 402 | bool full_waiters_pending; |
| 403 | bool wakeup_full; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 404 | }; |
| 405 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 406 | /* |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 407 | * Structure to hold event state and handle nested events. |
| 408 | */ |
| 409 | struct rb_event_info { |
| 410 | u64 ts; |
| 411 | u64 delta; |
| 412 | unsigned long length; |
| 413 | struct buffer_page *tail_page; |
| 414 | int add_timestamp; |
| 415 | }; |
| 416 | |
| 417 | /* |
Steven Rostedt (Red Hat) | a497adb | 2015-05-29 10:32:28 -0400 | [diff] [blame] | 418 | * Used for which event context the event is in. |
| 419 | * NMI = 0 |
| 420 | * IRQ = 1 |
| 421 | * SOFTIRQ = 2 |
| 422 | * NORMAL = 3 |
| 423 | * |
| 424 | * See trace_recursive_lock() comment below for more details. |
| 425 | */ |
| 426 | enum { |
| 427 | RB_CTX_NMI, |
| 428 | RB_CTX_IRQ, |
| 429 | RB_CTX_SOFTIRQ, |
| 430 | RB_CTX_NORMAL, |
| 431 | RB_CTX_MAX |
| 432 | }; |
| 433 | |
| 434 | /* |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 435 | * head_page == tail_page && head == tail then buffer is empty. |
| 436 | */ |
| 437 | struct ring_buffer_per_cpu { |
| 438 | int cpu; |
Richard Kennedy | 985023d | 2010-03-25 11:27:36 +0000 | [diff] [blame] | 439 | atomic_t record_disabled; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 440 | struct ring_buffer *buffer; |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 441 | raw_spinlock_t reader_lock; /* serialize readers */ |
Thomas Gleixner | 445c895 | 2009-12-02 19:49:50 +0100 | [diff] [blame] | 442 | arch_spinlock_t lock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 443 | struct lock_class_key lock_key; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 444 | unsigned long nr_pages; |
Steven Rostedt (Red Hat) | 58a09ec | 2015-05-27 10:27:47 -0400 | [diff] [blame] | 445 | unsigned int current_context; |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 446 | struct list_head *pages; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 447 | struct buffer_page *head_page; /* read from head */ |
| 448 | struct buffer_page *tail_page; /* write to tail */ |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 449 | struct buffer_page *commit_page; /* committed pages */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 450 | struct buffer_page *reader_page; |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 451 | unsigned long lost_events; |
| 452 | unsigned long last_overrun; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 453 | local_t entries_bytes; |
Steven Rostedt | e4906ef | 2009-04-30 20:49:44 -0400 | [diff] [blame] | 454 | local_t entries; |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 455 | local_t overrun; |
| 456 | local_t commit_overrun; |
| 457 | local_t dropped_events; |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 458 | local_t committing; |
| 459 | local_t commits; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 460 | unsigned long read; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 461 | unsigned long read_bytes; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 462 | u64 write_stamp; |
| 463 | u64 read_stamp; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 464 | /* ring buffer pages to update, > 0 to add, < 0 to remove */ |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 465 | long nr_pages_to_update; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 466 | struct list_head new_pages; /* new pages to add */ |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 467 | struct work_struct update_pages_work; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 468 | struct completion update_done; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 469 | |
| 470 | struct rb_irq_work irq_work; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 471 | }; |
| 472 | |
| 473 | struct ring_buffer { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 474 | unsigned flags; |
| 475 | int cpus; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 476 | atomic_t record_disabled; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 477 | atomic_t resize_disabled; |
Arnaldo Carvalho de Melo | 00f62f6 | 2009-02-09 17:04:06 -0200 | [diff] [blame] | 478 | cpumask_var_t cpumask; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 479 | |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 480 | struct lock_class_key *reader_lock_key; |
| 481 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 482 | struct mutex mutex; |
| 483 | |
| 484 | struct ring_buffer_per_cpu **buffers; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 485 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 486 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 487 | struct notifier_block cpu_notify; |
| 488 | #endif |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 489 | u64 (*clock)(void); |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 490 | |
| 491 | struct rb_irq_work irq_work; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 492 | }; |
| 493 | |
| 494 | struct ring_buffer_iter { |
| 495 | struct ring_buffer_per_cpu *cpu_buffer; |
| 496 | unsigned long head; |
| 497 | struct buffer_page *head_page; |
Steven Rostedt | 492a74f | 2010-01-25 15:17:47 -0500 | [diff] [blame] | 498 | struct buffer_page *cache_reader_page; |
| 499 | unsigned long cache_read; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 500 | u64 read_stamp; |
| 501 | }; |
| 502 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 503 | /* |
| 504 | * rb_wake_up_waiters - wake up tasks waiting for ring buffer input |
| 505 | * |
| 506 | * Schedules a delayed work to wake up any task that is blocked on the |
| 507 | * ring buffer waiters queue. |
| 508 | */ |
| 509 | static void rb_wake_up_waiters(struct irq_work *work) |
| 510 | { |
| 511 | struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work); |
| 512 | |
| 513 | wake_up_all(&rbwork->waiters); |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 514 | if (rbwork->wakeup_full) { |
| 515 | rbwork->wakeup_full = false; |
| 516 | wake_up_all(&rbwork->full_waiters); |
| 517 | } |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 518 | } |
| 519 | |
| 520 | /** |
| 521 | * ring_buffer_wait - wait for input to the ring buffer |
| 522 | * @buffer: buffer to wait on |
| 523 | * @cpu: the cpu buffer to wait on |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 524 | * @full: wait until a full page is available, if @cpu != RING_BUFFER_ALL_CPUS |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 525 | * |
| 526 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon |
| 527 | * as data is added to any of the @buffer's cpu buffers. Otherwise |
| 528 | * it will wait for data to be added to a specific cpu buffer. |
| 529 | */ |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 530 | int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full) |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 531 | { |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 532 | struct ring_buffer_per_cpu *uninitialized_var(cpu_buffer); |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 533 | DEFINE_WAIT(wait); |
| 534 | struct rb_irq_work *work; |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 535 | int ret = 0; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 536 | |
| 537 | /* |
| 538 | * Depending on what the caller is waiting for, either any |
| 539 | * data in any cpu buffer, or a specific buffer, put the |
| 540 | * caller on the appropriate wait queue. |
| 541 | */ |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 542 | if (cpu == RING_BUFFER_ALL_CPUS) { |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 543 | work = &buffer->irq_work; |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 544 | /* Full only makes sense on per cpu reads */ |
| 545 | full = false; |
| 546 | } else { |
Steven Rostedt (Red Hat) | 8b8b368 | 2014-06-10 09:46:00 -0400 | [diff] [blame] | 547 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 548 | return -ENODEV; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 549 | cpu_buffer = buffer->buffers[cpu]; |
| 550 | work = &cpu_buffer->irq_work; |
| 551 | } |
| 552 | |
| 553 | |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 554 | while (true) { |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 555 | if (full) |
| 556 | prepare_to_wait(&work->full_waiters, &wait, TASK_INTERRUPTIBLE); |
| 557 | else |
| 558 | prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE); |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 559 | |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 560 | /* |
| 561 | * The events can happen in critical sections where |
| 562 | * checking a work queue can cause deadlocks. |
| 563 | * After adding a task to the queue, this flag is set |
| 564 | * only to notify events to try to wake up the queue |
| 565 | * using irq_work. |
| 566 | * |
| 567 | * We don't clear it even if the buffer is no longer |
| 568 | * empty. The flag only causes the next event to run |
| 569 | * irq_work to do the work queue wake up. The worse |
| 570 | * that can happen if we race with !trace_empty() is that |
| 571 | * an event will cause an irq_work to try to wake up |
| 572 | * an empty queue. |
| 573 | * |
| 574 | * There's no reason to protect this flag either, as |
| 575 | * the work queue and irq_work logic will do the necessary |
| 576 | * synchronization for the wake ups. The only thing |
| 577 | * that is necessary is that the wake up happens after |
| 578 | * a task has been queued. It's OK for spurious wake ups. |
| 579 | */ |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 580 | if (full) |
| 581 | work->full_waiters_pending = true; |
| 582 | else |
| 583 | work->waiters_pending = true; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 584 | |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 585 | if (signal_pending(current)) { |
| 586 | ret = -EINTR; |
| 587 | break; |
| 588 | } |
| 589 | |
| 590 | if (cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) |
| 591 | break; |
| 592 | |
| 593 | if (cpu != RING_BUFFER_ALL_CPUS && |
| 594 | !ring_buffer_empty_cpu(buffer, cpu)) { |
| 595 | unsigned long flags; |
| 596 | bool pagebusy; |
| 597 | |
| 598 | if (!full) |
| 599 | break; |
| 600 | |
| 601 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 602 | pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; |
| 603 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
| 604 | |
| 605 | if (!pagebusy) |
| 606 | break; |
| 607 | } |
| 608 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 609 | schedule(); |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 610 | } |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 611 | |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 612 | if (full) |
| 613 | finish_wait(&work->full_waiters, &wait); |
| 614 | else |
| 615 | finish_wait(&work->waiters, &wait); |
Rabin Vincent | e30f53a | 2014-11-10 19:46:34 +0100 | [diff] [blame] | 616 | |
| 617 | return ret; |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 618 | } |
| 619 | |
| 620 | /** |
| 621 | * ring_buffer_poll_wait - poll on buffer input |
| 622 | * @buffer: buffer to wait on |
| 623 | * @cpu: the cpu buffer to wait on |
| 624 | * @filp: the file descriptor |
| 625 | * @poll_table: The poll descriptor |
| 626 | * |
| 627 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon |
| 628 | * as data is added to any of the @buffer's cpu buffers. Otherwise |
| 629 | * it will wait for data to be added to a specific cpu buffer. |
| 630 | * |
| 631 | * Returns POLLIN | POLLRDNORM if data exists in the buffers, |
| 632 | * zero otherwise. |
| 633 | */ |
| 634 | int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, |
| 635 | struct file *filp, poll_table *poll_table) |
| 636 | { |
| 637 | struct ring_buffer_per_cpu *cpu_buffer; |
| 638 | struct rb_irq_work *work; |
| 639 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 640 | if (cpu == RING_BUFFER_ALL_CPUS) |
| 641 | work = &buffer->irq_work; |
| 642 | else { |
Steven Rostedt (Red Hat) | 6721cb6 | 2013-05-23 14:21:36 -0400 | [diff] [blame] | 643 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 644 | return -EINVAL; |
| 645 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 646 | cpu_buffer = buffer->buffers[cpu]; |
| 647 | work = &cpu_buffer->irq_work; |
| 648 | } |
| 649 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 650 | poll_wait(filp, &work->waiters, poll_table); |
Josef Bacik | 4ce97db | 2014-08-25 13:59:41 -0400 | [diff] [blame] | 651 | work->waiters_pending = true; |
| 652 | /* |
| 653 | * There's a tight race between setting the waiters_pending and |
| 654 | * checking if the ring buffer is empty. Once the waiters_pending bit |
| 655 | * is set, the next event will wake the task up, but we can get stuck |
| 656 | * if there's only a single event in. |
| 657 | * |
| 658 | * FIXME: Ideally, we need a memory barrier on the writer side as well, |
| 659 | * but adding a memory barrier to all events will cause too much of a |
| 660 | * performance hit in the fast path. We only need a memory barrier when |
| 661 | * the buffer goes from empty to having content. But as this race is |
| 662 | * extremely small, and it's not a problem if another event comes in, we |
| 663 | * will fix it later. |
| 664 | */ |
| 665 | smp_mb(); |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 666 | |
| 667 | if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || |
| 668 | (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) |
| 669 | return POLLIN | POLLRDNORM; |
| 670 | return 0; |
| 671 | } |
| 672 | |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 673 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
Steven Rostedt | 077c540 | 2009-09-03 19:53:46 -0400 | [diff] [blame] | 674 | #define RB_WARN_ON(b, cond) \ |
| 675 | ({ \ |
| 676 | int _____ret = unlikely(cond); \ |
| 677 | if (_____ret) { \ |
| 678 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ |
| 679 | struct ring_buffer_per_cpu *__b = \ |
| 680 | (void *)b; \ |
| 681 | atomic_inc(&__b->buffer->record_disabled); \ |
| 682 | } else \ |
| 683 | atomic_inc(&b->record_disabled); \ |
| 684 | WARN_ON(1); \ |
| 685 | } \ |
| 686 | _____ret; \ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 687 | }) |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 688 | |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 689 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
| 690 | #define DEBUG_SHIFT 0 |
| 691 | |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 692 | static inline u64 rb_time_stamp(struct ring_buffer *buffer) |
Steven Rostedt | 88eb012 | 2009-05-11 16:28:23 -0400 | [diff] [blame] | 693 | { |
| 694 | /* shift to debug/test normalization and TIME_EXTENTS */ |
| 695 | return buffer->clock() << DEBUG_SHIFT; |
| 696 | } |
| 697 | |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 698 | u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) |
| 699 | { |
| 700 | u64 time; |
| 701 | |
| 702 | preempt_disable_notrace(); |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 703 | time = rb_time_stamp(buffer); |
Peter Zijlstra | 56f9da8 | 2019-04-23 22:03:18 +0200 | [diff] [blame] | 704 | preempt_enable_notrace(); |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 705 | |
| 706 | return time; |
| 707 | } |
| 708 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); |
| 709 | |
| 710 | void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, |
| 711 | int cpu, u64 *ts) |
| 712 | { |
| 713 | /* Just stupid testing the normalize function and deltas */ |
| 714 | *ts >>= DEBUG_SHIFT; |
| 715 | } |
| 716 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); |
| 717 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 718 | /* |
| 719 | * Making the ring buffer lockless makes things tricky. |
| 720 | * Although writes only happen on the CPU that they are on, |
| 721 | * and they only need to worry about interrupts. Reads can |
| 722 | * happen on any CPU. |
| 723 | * |
| 724 | * The reader page is always off the ring buffer, but when the |
| 725 | * reader finishes with a page, it needs to swap its page with |
| 726 | * a new one from the buffer. The reader needs to take from |
| 727 | * the head (writes go to the tail). But if a writer is in overwrite |
| 728 | * mode and wraps, it must push the head page forward. |
| 729 | * |
| 730 | * Here lies the problem. |
| 731 | * |
| 732 | * The reader must be careful to replace only the head page, and |
| 733 | * not another one. As described at the top of the file in the |
| 734 | * ASCII art, the reader sets its old page to point to the next |
| 735 | * page after head. It then sets the page after head to point to |
| 736 | * the old reader page. But if the writer moves the head page |
| 737 | * during this operation, the reader could end up with the tail. |
| 738 | * |
| 739 | * We use cmpxchg to help prevent this race. We also do something |
| 740 | * special with the page before head. We set the LSB to 1. |
| 741 | * |
| 742 | * When the writer must push the page forward, it will clear the |
| 743 | * bit that points to the head page, move the head, and then set |
| 744 | * the bit that points to the new head page. |
| 745 | * |
| 746 | * We also don't want an interrupt coming in and moving the head |
| 747 | * page on another writer. Thus we use the second LSB to catch |
| 748 | * that too. Thus: |
| 749 | * |
| 750 | * head->list->prev->next bit 1 bit 0 |
| 751 | * ------- ------- |
| 752 | * Normal page 0 0 |
| 753 | * Points to head page 0 1 |
| 754 | * New head page 1 0 |
| 755 | * |
| 756 | * Note we can not trust the prev pointer of the head page, because: |
| 757 | * |
| 758 | * +----+ +-----+ +-----+ |
| 759 | * | |------>| T |---X--->| N | |
| 760 | * | |<------| | | | |
| 761 | * +----+ +-----+ +-----+ |
| 762 | * ^ ^ | |
| 763 | * | +-----+ | | |
| 764 | * +----------| R |----------+ | |
| 765 | * | |<-----------+ |
| 766 | * +-----+ |
| 767 | * |
| 768 | * Key: ---X--> HEAD flag set in pointer |
| 769 | * T Tail page |
| 770 | * R Reader page |
| 771 | * N Next page |
| 772 | * |
| 773 | * (see __rb_reserve_next() to see where this happens) |
| 774 | * |
| 775 | * What the above shows is that the reader just swapped out |
| 776 | * the reader page with a page in the buffer, but before it |
| 777 | * could make the new header point back to the new page added |
| 778 | * it was preempted by a writer. The writer moved forward onto |
| 779 | * the new page added by the reader and is about to move forward |
| 780 | * again. |
| 781 | * |
| 782 | * You can see, it is legitimate for the previous pointer of |
| 783 | * the head (or any page) not to point back to itself. But only |
| 784 | * temporarially. |
| 785 | */ |
| 786 | |
| 787 | #define RB_PAGE_NORMAL 0UL |
| 788 | #define RB_PAGE_HEAD 1UL |
| 789 | #define RB_PAGE_UPDATE 2UL |
| 790 | |
| 791 | |
| 792 | #define RB_FLAG_MASK 3UL |
| 793 | |
| 794 | /* PAGE_MOVED is not part of the mask */ |
| 795 | #define RB_PAGE_MOVED 4UL |
| 796 | |
| 797 | /* |
| 798 | * rb_list_head - remove any bit |
| 799 | */ |
| 800 | static struct list_head *rb_list_head(struct list_head *list) |
| 801 | { |
| 802 | unsigned long val = (unsigned long)list; |
| 803 | |
| 804 | return (struct list_head *)(val & ~RB_FLAG_MASK); |
| 805 | } |
| 806 | |
| 807 | /* |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 808 | * rb_is_head_page - test if the given page is the head page |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 809 | * |
| 810 | * Because the reader may move the head_page pointer, we can |
| 811 | * not trust what the head page is (it may be pointing to |
| 812 | * the reader page). But if the next page is a header page, |
| 813 | * its flags will be non zero. |
| 814 | */ |
Jesper Juhl | 42b16b3 | 2011-01-17 00:09:38 +0100 | [diff] [blame] | 815 | static inline int |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 816 | rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, |
| 817 | struct buffer_page *page, struct list_head *list) |
| 818 | { |
| 819 | unsigned long val; |
| 820 | |
| 821 | val = (unsigned long)list->next; |
| 822 | |
| 823 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) |
| 824 | return RB_PAGE_MOVED; |
| 825 | |
| 826 | return val & RB_FLAG_MASK; |
| 827 | } |
| 828 | |
| 829 | /* |
| 830 | * rb_is_reader_page |
| 831 | * |
| 832 | * The unique thing about the reader page, is that, if the |
| 833 | * writer is ever on it, the previous pointer never points |
| 834 | * back to the reader page. |
| 835 | */ |
Yaowei Bai | 06ca320 | 2015-09-29 22:43:31 +0800 | [diff] [blame] | 836 | static bool rb_is_reader_page(struct buffer_page *page) |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 837 | { |
| 838 | struct list_head *list = page->list.prev; |
| 839 | |
| 840 | return rb_list_head(list->next) != &page->list; |
| 841 | } |
| 842 | |
| 843 | /* |
| 844 | * rb_set_list_to_head - set a list_head to be pointing to head. |
| 845 | */ |
| 846 | static void rb_set_list_to_head(struct ring_buffer_per_cpu *cpu_buffer, |
| 847 | struct list_head *list) |
| 848 | { |
| 849 | unsigned long *ptr; |
| 850 | |
| 851 | ptr = (unsigned long *)&list->next; |
| 852 | *ptr |= RB_PAGE_HEAD; |
| 853 | *ptr &= ~RB_PAGE_UPDATE; |
| 854 | } |
| 855 | |
| 856 | /* |
| 857 | * rb_head_page_activate - sets up head page |
| 858 | */ |
| 859 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) |
| 860 | { |
| 861 | struct buffer_page *head; |
| 862 | |
| 863 | head = cpu_buffer->head_page; |
| 864 | if (!head) |
| 865 | return; |
| 866 | |
| 867 | /* |
| 868 | * Set the previous list pointer to have the HEAD flag. |
| 869 | */ |
| 870 | rb_set_list_to_head(cpu_buffer, head->list.prev); |
| 871 | } |
| 872 | |
| 873 | static void rb_list_head_clear(struct list_head *list) |
| 874 | { |
| 875 | unsigned long *ptr = (unsigned long *)&list->next; |
| 876 | |
| 877 | *ptr &= ~RB_FLAG_MASK; |
| 878 | } |
| 879 | |
| 880 | /* |
| 881 | * rb_head_page_dactivate - clears head page ptr (for free list) |
| 882 | */ |
| 883 | static void |
| 884 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) |
| 885 | { |
| 886 | struct list_head *hd; |
| 887 | |
| 888 | /* Go through the whole list and clear any pointers found. */ |
| 889 | rb_list_head_clear(cpu_buffer->pages); |
| 890 | |
| 891 | list_for_each(hd, cpu_buffer->pages) |
| 892 | rb_list_head_clear(hd); |
| 893 | } |
| 894 | |
| 895 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, |
| 896 | struct buffer_page *head, |
| 897 | struct buffer_page *prev, |
| 898 | int old_flag, int new_flag) |
| 899 | { |
| 900 | struct list_head *list; |
| 901 | unsigned long val = (unsigned long)&head->list; |
| 902 | unsigned long ret; |
| 903 | |
| 904 | list = &prev->list; |
| 905 | |
| 906 | val &= ~RB_FLAG_MASK; |
| 907 | |
Steven Rostedt | 08a4081 | 2009-09-14 09:31:35 -0400 | [diff] [blame] | 908 | ret = cmpxchg((unsigned long *)&list->next, |
| 909 | val | old_flag, val | new_flag); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 910 | |
| 911 | /* check if the reader took the page */ |
| 912 | if ((ret & ~RB_FLAG_MASK) != val) |
| 913 | return RB_PAGE_MOVED; |
| 914 | |
| 915 | return ret & RB_FLAG_MASK; |
| 916 | } |
| 917 | |
| 918 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, |
| 919 | struct buffer_page *head, |
| 920 | struct buffer_page *prev, |
| 921 | int old_flag) |
| 922 | { |
| 923 | return rb_head_page_set(cpu_buffer, head, prev, |
| 924 | old_flag, RB_PAGE_UPDATE); |
| 925 | } |
| 926 | |
| 927 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, |
| 928 | struct buffer_page *head, |
| 929 | struct buffer_page *prev, |
| 930 | int old_flag) |
| 931 | { |
| 932 | return rb_head_page_set(cpu_buffer, head, prev, |
| 933 | old_flag, RB_PAGE_HEAD); |
| 934 | } |
| 935 | |
| 936 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, |
| 937 | struct buffer_page *head, |
| 938 | struct buffer_page *prev, |
| 939 | int old_flag) |
| 940 | { |
| 941 | return rb_head_page_set(cpu_buffer, head, prev, |
| 942 | old_flag, RB_PAGE_NORMAL); |
| 943 | } |
| 944 | |
| 945 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, |
| 946 | struct buffer_page **bpage) |
| 947 | { |
| 948 | struct list_head *p = rb_list_head((*bpage)->list.next); |
| 949 | |
| 950 | *bpage = list_entry(p, struct buffer_page, list); |
| 951 | } |
| 952 | |
| 953 | static struct buffer_page * |
| 954 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) |
| 955 | { |
| 956 | struct buffer_page *head; |
| 957 | struct buffer_page *page; |
| 958 | struct list_head *list; |
| 959 | int i; |
| 960 | |
| 961 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) |
| 962 | return NULL; |
| 963 | |
| 964 | /* sanity check */ |
| 965 | list = cpu_buffer->pages; |
| 966 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) |
| 967 | return NULL; |
| 968 | |
| 969 | page = head = cpu_buffer->head_page; |
| 970 | /* |
| 971 | * It is possible that the writer moves the header behind |
| 972 | * where we started, and we miss in one loop. |
| 973 | * A second loop should grab the header, but we'll do |
| 974 | * three loops just because I'm paranoid. |
| 975 | */ |
| 976 | for (i = 0; i < 3; i++) { |
| 977 | do { |
| 978 | if (rb_is_head_page(cpu_buffer, page, page->list.prev)) { |
| 979 | cpu_buffer->head_page = page; |
| 980 | return page; |
| 981 | } |
| 982 | rb_inc_page(cpu_buffer, &page); |
| 983 | } while (page != head); |
| 984 | } |
| 985 | |
| 986 | RB_WARN_ON(cpu_buffer, 1); |
| 987 | |
| 988 | return NULL; |
| 989 | } |
| 990 | |
| 991 | static int rb_head_page_replace(struct buffer_page *old, |
| 992 | struct buffer_page *new) |
| 993 | { |
| 994 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; |
| 995 | unsigned long val; |
| 996 | unsigned long ret; |
| 997 | |
| 998 | val = *ptr & ~RB_FLAG_MASK; |
| 999 | val |= RB_PAGE_HEAD; |
| 1000 | |
Steven Rostedt | 08a4081 | 2009-09-14 09:31:35 -0400 | [diff] [blame] | 1001 | ret = cmpxchg(ptr, val, (unsigned long)&new->list); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1002 | |
| 1003 | return ret == val; |
| 1004 | } |
| 1005 | |
| 1006 | /* |
| 1007 | * rb_tail_page_update - move the tail page forward |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1008 | */ |
Steven Rostedt (Red Hat) | 7000498 | 2015-11-17 15:15:19 -0500 | [diff] [blame] | 1009 | static void rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1010 | struct buffer_page *tail_page, |
| 1011 | struct buffer_page *next_page) |
| 1012 | { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1013 | unsigned long old_entries; |
| 1014 | unsigned long old_write; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1015 | |
| 1016 | /* |
| 1017 | * The tail page now needs to be moved forward. |
| 1018 | * |
| 1019 | * We need to reset the tail page, but without messing |
| 1020 | * with possible erasing of data brought in by interrupts |
| 1021 | * that have moved the tail page and are currently on it. |
| 1022 | * |
| 1023 | * We add a counter to the write field to denote this. |
| 1024 | */ |
| 1025 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); |
| 1026 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); |
| 1027 | |
| 1028 | /* |
| 1029 | * Just make sure we have seen our old_write and synchronize |
| 1030 | * with any interrupts that come in. |
| 1031 | */ |
| 1032 | barrier(); |
| 1033 | |
| 1034 | /* |
| 1035 | * If the tail page is still the same as what we think |
| 1036 | * it is, then it is up to us to update the tail |
| 1037 | * pointer. |
| 1038 | */ |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 1039 | if (tail_page == READ_ONCE(cpu_buffer->tail_page)) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1040 | /* Zero the write counter */ |
| 1041 | unsigned long val = old_write & ~RB_WRITE_MASK; |
| 1042 | unsigned long eval = old_entries & ~RB_WRITE_MASK; |
| 1043 | |
| 1044 | /* |
| 1045 | * This will only succeed if an interrupt did |
| 1046 | * not come in and change it. In which case, we |
| 1047 | * do not want to modify it. |
Lai Jiangshan | da706d8 | 2009-07-15 16:27:30 +0800 | [diff] [blame] | 1048 | * |
| 1049 | * We add (void) to let the compiler know that we do not care |
| 1050 | * about the return value of these functions. We use the |
| 1051 | * cmpxchg to only update if an interrupt did not already |
| 1052 | * do it for us. If the cmpxchg fails, we don't care. |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1053 | */ |
Lai Jiangshan | da706d8 | 2009-07-15 16:27:30 +0800 | [diff] [blame] | 1054 | (void)local_cmpxchg(&next_page->write, old_write, val); |
| 1055 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1056 | |
| 1057 | /* |
| 1058 | * No need to worry about races with clearing out the commit. |
| 1059 | * it only can increment when a commit takes place. But that |
| 1060 | * only happens in the outer most nested commit. |
| 1061 | */ |
| 1062 | local_set(&next_page->page->commit, 0); |
| 1063 | |
Steven Rostedt (Red Hat) | 7000498 | 2015-11-17 15:15:19 -0500 | [diff] [blame] | 1064 | /* Again, either we update tail_page or an interrupt does */ |
| 1065 | (void)cmpxchg(&cpu_buffer->tail_page, tail_page, next_page); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1066 | } |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1067 | } |
| 1068 | |
| 1069 | static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, |
| 1070 | struct buffer_page *bpage) |
| 1071 | { |
| 1072 | unsigned long val = (unsigned long)bpage; |
| 1073 | |
| 1074 | if (RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK)) |
| 1075 | return 1; |
| 1076 | |
| 1077 | return 0; |
| 1078 | } |
| 1079 | |
| 1080 | /** |
| 1081 | * rb_check_list - make sure a pointer to a list has the last bits zero |
| 1082 | */ |
| 1083 | static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, |
| 1084 | struct list_head *list) |
| 1085 | { |
| 1086 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev)) |
| 1087 | return 1; |
| 1088 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next)) |
| 1089 | return 1; |
| 1090 | return 0; |
| 1091 | } |
| 1092 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1093 | /** |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 1094 | * rb_check_pages - integrity check of buffer pages |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1095 | * @cpu_buffer: CPU buffer with pages to test |
| 1096 | * |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 1097 | * As a safety measure we check to make sure the data pages have not |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1098 | * been corrupted. |
| 1099 | */ |
| 1100 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) |
| 1101 | { |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1102 | struct list_head *head = cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1103 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1104 | |
Steven Rostedt | 308f7ee | 2012-05-16 19:46:32 -0400 | [diff] [blame] | 1105 | /* Reset the head page if it exists */ |
| 1106 | if (cpu_buffer->head_page) |
| 1107 | rb_set_head_page(cpu_buffer); |
| 1108 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1109 | rb_head_page_deactivate(cpu_buffer); |
| 1110 | |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1111 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
| 1112 | return -1; |
| 1113 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) |
| 1114 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1115 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1116 | if (rb_check_list(cpu_buffer, head)) |
| 1117 | return -1; |
| 1118 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1119 | list_for_each_entry_safe(bpage, tmp, head, list) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1120 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1121 | bpage->list.next->prev != &bpage->list)) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1122 | return -1; |
| 1123 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1124 | bpage->list.prev->next != &bpage->list)) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1125 | return -1; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1126 | if (rb_check_list(cpu_buffer, &bpage->list)) |
| 1127 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1128 | } |
| 1129 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1130 | rb_head_page_activate(cpu_buffer); |
| 1131 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1132 | return 0; |
| 1133 | } |
| 1134 | |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1135 | static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1136 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1137 | struct buffer_page *bpage, *tmp; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1138 | long i; |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1139 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1140 | for (i = 0; i < nr_pages; i++) { |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1141 | struct page *page; |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1142 | /* |
| 1143 | * __GFP_NORETRY flag makes sure that the allocation fails |
| 1144 | * gracefully without invoking oom-killer and the system is |
| 1145 | * not destabilized. |
| 1146 | */ |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1147 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1148 | GFP_KERNEL | __GFP_NORETRY, |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1149 | cpu_to_node(cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1150 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1151 | goto free_pages; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1152 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1153 | list_add(&bpage->list, pages); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1154 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1155 | page = alloc_pages_node(cpu_to_node(cpu), |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1156 | GFP_KERNEL | __GFP_NORETRY, 0); |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1157 | if (!page) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1158 | goto free_pages; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1159 | bpage->page = page_address(page); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1160 | rb_init_page(bpage->page); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1161 | } |
| 1162 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1163 | return 0; |
| 1164 | |
| 1165 | free_pages: |
| 1166 | list_for_each_entry_safe(bpage, tmp, pages, list) { |
| 1167 | list_del_init(&bpage->list); |
| 1168 | free_buffer_page(bpage); |
| 1169 | } |
| 1170 | |
| 1171 | return -ENOMEM; |
| 1172 | } |
| 1173 | |
| 1174 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1175 | unsigned long nr_pages) |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1176 | { |
| 1177 | LIST_HEAD(pages); |
| 1178 | |
| 1179 | WARN_ON(!nr_pages); |
| 1180 | |
| 1181 | if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu)) |
| 1182 | return -ENOMEM; |
| 1183 | |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1184 | /* |
| 1185 | * The ring buffer page list is a circular list that does not |
| 1186 | * start and end with a list head. All page list items point to |
| 1187 | * other pages. |
| 1188 | */ |
| 1189 | cpu_buffer->pages = pages.next; |
| 1190 | list_del(&pages); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1191 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1192 | cpu_buffer->nr_pages = nr_pages; |
| 1193 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1194 | rb_check_pages(cpu_buffer); |
| 1195 | |
| 1196 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1197 | } |
| 1198 | |
| 1199 | static struct ring_buffer_per_cpu * |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1200 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, long nr_pages, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1201 | { |
| 1202 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1203 | struct buffer_page *bpage; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1204 | struct page *page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1205 | int ret; |
| 1206 | |
| 1207 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), |
| 1208 | GFP_KERNEL, cpu_to_node(cpu)); |
| 1209 | if (!cpu_buffer) |
| 1210 | return NULL; |
| 1211 | |
| 1212 | cpu_buffer->cpu = cpu; |
| 1213 | cpu_buffer->buffer = buffer; |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1214 | raw_spin_lock_init(&cpu_buffer->reader_lock); |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1215 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
Thomas Gleixner | edc35bd | 2009-12-03 12:38:57 +0100 | [diff] [blame] | 1216 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1217 | INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1218 | init_completion(&cpu_buffer->update_done); |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 1219 | init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters); |
Steven Rostedt (Red Hat) | f1dc672 | 2013-03-04 17:33:05 -0500 | [diff] [blame] | 1220 | init_waitqueue_head(&cpu_buffer->irq_work.waiters); |
Steven Rostedt (Red Hat) | 1e0d671 | 2015-02-10 22:14:53 -0500 | [diff] [blame] | 1221 | init_waitqueue_head(&cpu_buffer->irq_work.full_waiters); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1222 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1223 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1224 | GFP_KERNEL, cpu_to_node(cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1225 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1226 | goto fail_free_buffer; |
| 1227 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1228 | rb_check_bpage(cpu_buffer, bpage); |
| 1229 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1230 | cpu_buffer->reader_page = bpage; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1231 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0); |
| 1232 | if (!page) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1233 | goto fail_free_reader; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1234 | bpage->page = page_address(page); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1235 | rb_init_page(bpage->page); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1236 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1237 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
Vaibhav Nagarnaik | 44b9946 | 2012-06-22 11:50:05 -0700 | [diff] [blame] | 1238 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1239 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1240 | ret = rb_allocate_pages(cpu_buffer, nr_pages); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1241 | if (ret < 0) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1242 | goto fail_free_reader; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1243 | |
| 1244 | cpu_buffer->head_page |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1245 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1246 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1247 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1248 | rb_head_page_activate(cpu_buffer); |
| 1249 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1250 | return cpu_buffer; |
| 1251 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1252 | fail_free_reader: |
| 1253 | free_buffer_page(cpu_buffer->reader_page); |
| 1254 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1255 | fail_free_buffer: |
| 1256 | kfree(cpu_buffer); |
| 1257 | return NULL; |
| 1258 | } |
| 1259 | |
| 1260 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) |
| 1261 | { |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1262 | struct list_head *head = cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1263 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1264 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1265 | free_buffer_page(cpu_buffer->reader_page); |
| 1266 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1267 | rb_head_page_deactivate(cpu_buffer); |
| 1268 | |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1269 | if (head) { |
| 1270 | list_for_each_entry_safe(bpage, tmp, head, list) { |
| 1271 | list_del_init(&bpage->list); |
| 1272 | free_buffer_page(bpage); |
| 1273 | } |
| 1274 | bpage = list_entry(head, struct buffer_page, list); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1275 | free_buffer_page(bpage); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1276 | } |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1277 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1278 | kfree(cpu_buffer); |
| 1279 | } |
| 1280 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 1281 | #ifdef CONFIG_HOTPLUG_CPU |
Frederic Weisbecker | 09c9e84 | 2009-03-21 04:33:36 +0100 | [diff] [blame] | 1282 | static int rb_cpu_notify(struct notifier_block *self, |
| 1283 | unsigned long action, void *hcpu); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1284 | #endif |
| 1285 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1286 | /** |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 1287 | * __ring_buffer_alloc - allocate a new ring_buffer |
Robert Richter | 68814b5 | 2008-11-24 12:24:12 +0100 | [diff] [blame] | 1288 | * @size: the size in bytes per cpu that is needed. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1289 | * @flags: attributes to set for the ring buffer. |
| 1290 | * |
| 1291 | * Currently the only flag that is available is the RB_FL_OVERWRITE |
| 1292 | * flag. This flag means that the buffer will overwrite old data |
| 1293 | * when the buffer wraps. If this flag is not set, the buffer will |
| 1294 | * drop data when the tail hits the head. |
| 1295 | */ |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1296 | struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
| 1297 | struct lock_class_key *key) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1298 | { |
| 1299 | struct ring_buffer *buffer; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1300 | long nr_pages; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1301 | int bsize; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1302 | int cpu; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1303 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1304 | /* keep it in its own cache line */ |
| 1305 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), |
| 1306 | GFP_KERNEL); |
| 1307 | if (!buffer) |
| 1308 | return NULL; |
| 1309 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1310 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
| 1311 | goto fail_free_buffer; |
| 1312 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1313 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1314 | buffer->flags = flags; |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 1315 | buffer->clock = trace_clock_local; |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1316 | buffer->reader_lock_key = key; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1317 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 1318 | init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); |
Steven Rostedt (Red Hat) | f1dc672 | 2013-03-04 17:33:05 -0500 | [diff] [blame] | 1319 | init_waitqueue_head(&buffer->irq_work.waiters); |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 1320 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1321 | /* need at least two pages */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1322 | if (nr_pages < 2) |
| 1323 | nr_pages = 2; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1324 | |
Frederic Weisbecker | 3bf832c | 2009-03-19 14:47:33 +0100 | [diff] [blame] | 1325 | /* |
| 1326 | * In case of non-hotplug cpu, if the ring-buffer is allocated |
| 1327 | * in early initcall, it will not be notified of secondary cpus. |
| 1328 | * In that off case, we need to allocate for all possible cpus. |
| 1329 | */ |
| 1330 | #ifdef CONFIG_HOTPLUG_CPU |
Srivatsa S. Bhat | d39ad27 | 2014-03-11 02:11:56 +0530 | [diff] [blame] | 1331 | cpu_notifier_register_begin(); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1332 | cpumask_copy(buffer->cpumask, cpu_online_mask); |
Frederic Weisbecker | 3bf832c | 2009-03-19 14:47:33 +0100 | [diff] [blame] | 1333 | #else |
| 1334 | cpumask_copy(buffer->cpumask, cpu_possible_mask); |
| 1335 | #endif |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1336 | buffer->cpus = nr_cpu_ids; |
| 1337 | |
| 1338 | bsize = sizeof(void *) * nr_cpu_ids; |
| 1339 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), |
| 1340 | GFP_KERNEL); |
| 1341 | if (!buffer->buffers) |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1342 | goto fail_free_cpumask; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1343 | |
| 1344 | for_each_buffer_cpu(buffer, cpu) { |
| 1345 | buffer->buffers[cpu] = |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1346 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1347 | if (!buffer->buffers[cpu]) |
| 1348 | goto fail_free_buffers; |
| 1349 | } |
| 1350 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 1351 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1352 | buffer->cpu_notify.notifier_call = rb_cpu_notify; |
| 1353 | buffer->cpu_notify.priority = 0; |
Srivatsa S. Bhat | d39ad27 | 2014-03-11 02:11:56 +0530 | [diff] [blame] | 1354 | __register_cpu_notifier(&buffer->cpu_notify); |
| 1355 | cpu_notifier_register_done(); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1356 | #endif |
| 1357 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1358 | mutex_init(&buffer->mutex); |
| 1359 | |
| 1360 | return buffer; |
| 1361 | |
| 1362 | fail_free_buffers: |
| 1363 | for_each_buffer_cpu(buffer, cpu) { |
| 1364 | if (buffer->buffers[cpu]) |
| 1365 | rb_free_cpu_buffer(buffer->buffers[cpu]); |
| 1366 | } |
| 1367 | kfree(buffer->buffers); |
| 1368 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1369 | fail_free_cpumask: |
| 1370 | free_cpumask_var(buffer->cpumask); |
Srivatsa S. Bhat | d39ad27 | 2014-03-11 02:11:56 +0530 | [diff] [blame] | 1371 | #ifdef CONFIG_HOTPLUG_CPU |
| 1372 | cpu_notifier_register_done(); |
| 1373 | #endif |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1374 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1375 | fail_free_buffer: |
| 1376 | kfree(buffer); |
| 1377 | return NULL; |
| 1378 | } |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1379 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1380 | |
| 1381 | /** |
| 1382 | * ring_buffer_free - free a ring buffer. |
| 1383 | * @buffer: the buffer to free. |
| 1384 | */ |
| 1385 | void |
| 1386 | ring_buffer_free(struct ring_buffer *buffer) |
| 1387 | { |
| 1388 | int cpu; |
| 1389 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 1390 | #ifdef CONFIG_HOTPLUG_CPU |
Srivatsa S. Bhat | d39ad27 | 2014-03-11 02:11:56 +0530 | [diff] [blame] | 1391 | cpu_notifier_register_begin(); |
| 1392 | __unregister_cpu_notifier(&buffer->cpu_notify); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1393 | #endif |
| 1394 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1395 | for_each_buffer_cpu(buffer, cpu) |
| 1396 | rb_free_cpu_buffer(buffer->buffers[cpu]); |
| 1397 | |
Srivatsa S. Bhat | d39ad27 | 2014-03-11 02:11:56 +0530 | [diff] [blame] | 1398 | #ifdef CONFIG_HOTPLUG_CPU |
| 1399 | cpu_notifier_register_done(); |
| 1400 | #endif |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1401 | |
Eric Dumazet | bd3f022 | 2009-08-07 12:49:29 +0200 | [diff] [blame] | 1402 | kfree(buffer->buffers); |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1403 | free_cpumask_var(buffer->cpumask); |
| 1404 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1405 | kfree(buffer); |
| 1406 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1407 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1408 | |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 1409 | void ring_buffer_set_clock(struct ring_buffer *buffer, |
| 1410 | u64 (*clock)(void)) |
| 1411 | { |
| 1412 | buffer->clock = clock; |
| 1413 | } |
| 1414 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1415 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
| 1416 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1417 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1418 | { |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1419 | return local_read(&bpage->entries) & RB_WRITE_MASK; |
| 1420 | } |
| 1421 | |
| 1422 | static inline unsigned long rb_page_write(struct buffer_page *bpage) |
| 1423 | { |
| 1424 | return local_read(&bpage->write) & RB_WRITE_MASK; |
| 1425 | } |
| 1426 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1427 | static int |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1428 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1429 | { |
| 1430 | struct list_head *tail_page, *to_remove, *next_page; |
| 1431 | struct buffer_page *to_remove_page, *tmp_iter_page; |
| 1432 | struct buffer_page *last_page, *first_page; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1433 | unsigned long nr_removed; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1434 | unsigned long head_bit; |
| 1435 | int page_entries; |
| 1436 | |
| 1437 | head_bit = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1438 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1439 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1440 | atomic_inc(&cpu_buffer->record_disabled); |
| 1441 | /* |
| 1442 | * We don't race with the readers since we have acquired the reader |
| 1443 | * lock. We also don't race with writers after disabling recording. |
| 1444 | * This makes it easy to figure out the first and the last page to be |
| 1445 | * removed from the list. We unlink all the pages in between including |
| 1446 | * the first and last pages. This is done in a busy loop so that we |
| 1447 | * lose the least number of traces. |
| 1448 | * The pages are freed after we restart recording and unlock readers. |
| 1449 | */ |
| 1450 | tail_page = &cpu_buffer->tail_page->list; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1451 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1452 | /* |
| 1453 | * tail page might be on reader page, we remove the next page |
| 1454 | * from the ring buffer |
| 1455 | */ |
| 1456 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) |
| 1457 | tail_page = rb_list_head(tail_page->next); |
| 1458 | to_remove = tail_page; |
| 1459 | |
| 1460 | /* start of pages to remove */ |
| 1461 | first_page = list_entry(rb_list_head(to_remove->next), |
| 1462 | struct buffer_page, list); |
| 1463 | |
| 1464 | for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { |
| 1465 | to_remove = rb_list_head(to_remove)->next; |
| 1466 | head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1467 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1468 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1469 | next_page = rb_list_head(to_remove)->next; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1470 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1471 | /* |
| 1472 | * Now we remove all pages between tail_page and next_page. |
| 1473 | * Make sure that we have head_bit value preserved for the |
| 1474 | * next page |
| 1475 | */ |
| 1476 | tail_page->next = (struct list_head *)((unsigned long)next_page | |
| 1477 | head_bit); |
| 1478 | next_page = rb_list_head(next_page); |
| 1479 | next_page->prev = tail_page; |
| 1480 | |
| 1481 | /* make sure pages points to a valid page in the ring buffer */ |
| 1482 | cpu_buffer->pages = next_page; |
| 1483 | |
| 1484 | /* update head page */ |
| 1485 | if (head_bit) |
| 1486 | cpu_buffer->head_page = list_entry(next_page, |
| 1487 | struct buffer_page, list); |
| 1488 | |
| 1489 | /* |
| 1490 | * change read pointer to make sure any read iterators reset |
| 1491 | * themselves |
| 1492 | */ |
| 1493 | cpu_buffer->read = 0; |
| 1494 | |
| 1495 | /* pages are removed, resume tracing and then free the pages */ |
| 1496 | atomic_dec(&cpu_buffer->record_disabled); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1497 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1498 | |
| 1499 | RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); |
| 1500 | |
| 1501 | /* last buffer page to remove */ |
| 1502 | last_page = list_entry(rb_list_head(to_remove), struct buffer_page, |
| 1503 | list); |
| 1504 | tmp_iter_page = first_page; |
| 1505 | |
| 1506 | do { |
Vaibhav Nagarnaik | be910e7 | 2018-09-07 15:31:29 -0700 | [diff] [blame] | 1507 | cond_resched(); |
| 1508 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1509 | to_remove_page = tmp_iter_page; |
| 1510 | rb_inc_page(cpu_buffer, &tmp_iter_page); |
| 1511 | |
| 1512 | /* update the counters */ |
| 1513 | page_entries = rb_page_entries(to_remove_page); |
| 1514 | if (page_entries) { |
| 1515 | /* |
| 1516 | * If something was added to this page, it was full |
| 1517 | * since it is not the tail page. So we deduct the |
| 1518 | * bytes consumed in ring buffer from here. |
Vaibhav Nagarnaik | 48fdc72 | 2012-06-29 12:31:41 -0700 | [diff] [blame] | 1519 | * Increment overrun to account for the lost events. |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1520 | */ |
Vaibhav Nagarnaik | 48fdc72 | 2012-06-29 12:31:41 -0700 | [diff] [blame] | 1521 | local_add(page_entries, &cpu_buffer->overrun); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1522 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
| 1523 | } |
| 1524 | |
| 1525 | /* |
| 1526 | * We have already removed references to this list item, just |
| 1527 | * free up the buffer_page and its page |
| 1528 | */ |
| 1529 | free_buffer_page(to_remove_page); |
| 1530 | nr_removed--; |
| 1531 | |
| 1532 | } while (to_remove_page != last_page); |
| 1533 | |
| 1534 | RB_WARN_ON(cpu_buffer, nr_removed); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1535 | |
| 1536 | return nr_removed == 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1537 | } |
| 1538 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1539 | static int |
| 1540 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1541 | { |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1542 | struct list_head *pages = &cpu_buffer->new_pages; |
| 1543 | int retries, success; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1544 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1545 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1546 | /* |
| 1547 | * We are holding the reader lock, so the reader page won't be swapped |
| 1548 | * in the ring buffer. Now we are racing with the writer trying to |
| 1549 | * move head page and the tail page. |
| 1550 | * We are going to adapt the reader page update process where: |
| 1551 | * 1. We first splice the start and end of list of new pages between |
| 1552 | * the head page and its previous page. |
| 1553 | * 2. We cmpxchg the prev_page->next to point from head page to the |
| 1554 | * start of new pages list. |
| 1555 | * 3. Finally, we update the head->prev to the end of new list. |
| 1556 | * |
| 1557 | * We will try this process 10 times, to make sure that we don't keep |
| 1558 | * spinning. |
| 1559 | */ |
| 1560 | retries = 10; |
| 1561 | success = 0; |
| 1562 | while (retries--) { |
| 1563 | struct list_head *head_page, *prev_page, *r; |
| 1564 | struct list_head *last_page, *first_page; |
| 1565 | struct list_head *head_page_with_bit; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1566 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1567 | head_page = &rb_set_head_page(cpu_buffer)->list; |
Steven Rostedt | 54f7be5 | 2012-11-29 22:27:22 -0500 | [diff] [blame] | 1568 | if (!head_page) |
| 1569 | break; |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1570 | prev_page = head_page->prev; |
| 1571 | |
| 1572 | first_page = pages->next; |
| 1573 | last_page = pages->prev; |
| 1574 | |
| 1575 | head_page_with_bit = (struct list_head *) |
| 1576 | ((unsigned long)head_page | RB_PAGE_HEAD); |
| 1577 | |
| 1578 | last_page->next = head_page_with_bit; |
| 1579 | first_page->prev = prev_page; |
| 1580 | |
| 1581 | r = cmpxchg(&prev_page->next, head_page_with_bit, first_page); |
| 1582 | |
| 1583 | if (r == head_page_with_bit) { |
| 1584 | /* |
| 1585 | * yay, we replaced the page pointer to our new list, |
| 1586 | * now, we just have to update to head page's prev |
| 1587 | * pointer to point to end of list |
| 1588 | */ |
| 1589 | head_page->prev = last_page; |
| 1590 | success = 1; |
| 1591 | break; |
| 1592 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1593 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1594 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1595 | if (success) |
| 1596 | INIT_LIST_HEAD(pages); |
| 1597 | /* |
| 1598 | * If we weren't successful in adding in new pages, warn and stop |
| 1599 | * tracing |
| 1600 | */ |
| 1601 | RB_WARN_ON(cpu_buffer, !success); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1602 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1603 | |
| 1604 | /* free pages if they weren't inserted */ |
| 1605 | if (!success) { |
| 1606 | struct buffer_page *bpage, *tmp; |
| 1607 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
| 1608 | list) { |
| 1609 | list_del_init(&bpage->list); |
| 1610 | free_buffer_page(bpage); |
| 1611 | } |
| 1612 | } |
| 1613 | return success; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1614 | } |
| 1615 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1616 | static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1617 | { |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1618 | int success; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1619 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1620 | if (cpu_buffer->nr_pages_to_update > 0) |
| 1621 | success = rb_insert_pages(cpu_buffer); |
| 1622 | else |
| 1623 | success = rb_remove_pages(cpu_buffer, |
| 1624 | -cpu_buffer->nr_pages_to_update); |
| 1625 | |
| 1626 | if (success) |
| 1627 | cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1628 | } |
| 1629 | |
| 1630 | static void update_pages_handler(struct work_struct *work) |
| 1631 | { |
| 1632 | struct ring_buffer_per_cpu *cpu_buffer = container_of(work, |
| 1633 | struct ring_buffer_per_cpu, update_pages_work); |
| 1634 | rb_update_pages(cpu_buffer); |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1635 | complete(&cpu_buffer->update_done); |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1636 | } |
| 1637 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1638 | /** |
| 1639 | * ring_buffer_resize - resize the ring buffer |
| 1640 | * @buffer: the buffer to resize. |
| 1641 | * @size: the new size. |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 1642 | * @cpu_id: the cpu buffer to resize |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1643 | * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1644 | * Minimum size is 2 * BUF_PAGE_SIZE. |
| 1645 | * |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1646 | * Returns 0 on success and < 0 on failure. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1647 | */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1648 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, |
| 1649 | int cpu_id) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1650 | { |
| 1651 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 1652 | unsigned long nr_pages; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1653 | int cpu, err = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1654 | |
Ingo Molnar | ee51a1d | 2008-11-13 14:58:31 +0100 | [diff] [blame] | 1655 | /* |
| 1656 | * Always succeed at resizing a non-existent buffer: |
| 1657 | */ |
| 1658 | if (!buffer) |
| 1659 | return size; |
| 1660 | |
Steven Rostedt | 6a31e1f | 2012-05-23 15:35:17 -0400 | [diff] [blame] | 1661 | /* Make sure the requested buffer exists */ |
| 1662 | if (cpu_id != RING_BUFFER_ALL_CPUS && |
| 1663 | !cpumask_test_cpu(cpu_id, buffer->cpumask)) |
| 1664 | return size; |
| 1665 | |
Steven Rostedt (Red Hat) | 59643d1 | 2016-05-13 09:34:12 -0400 | [diff] [blame] | 1666 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1667 | |
| 1668 | /* we need a minimum of two pages */ |
Steven Rostedt (Red Hat) | 59643d1 | 2016-05-13 09:34:12 -0400 | [diff] [blame] | 1669 | if (nr_pages < 2) |
| 1670 | nr_pages = 2; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1671 | |
Steven Rostedt (Red Hat) | 59643d1 | 2016-05-13 09:34:12 -0400 | [diff] [blame] | 1672 | size = nr_pages * BUF_PAGE_SIZE; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1673 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1674 | /* |
| 1675 | * Don't succeed if resizing is disabled, as a reader might be |
| 1676 | * manipulating the ring buffer and is expecting a sane state while |
| 1677 | * this is true. |
| 1678 | */ |
| 1679 | if (atomic_read(&buffer->resize_disabled)) |
| 1680 | return -EBUSY; |
| 1681 | |
| 1682 | /* prevent another thread from changing buffer sizes */ |
| 1683 | mutex_lock(&buffer->mutex); |
| 1684 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1685 | if (cpu_id == RING_BUFFER_ALL_CPUS) { |
| 1686 | /* calculate the pages to update */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1687 | for_each_buffer_cpu(buffer, cpu) { |
| 1688 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1689 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1690 | cpu_buffer->nr_pages_to_update = nr_pages - |
| 1691 | cpu_buffer->nr_pages; |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1692 | /* |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1693 | * nothing more to do for removing pages or no update |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1694 | */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1695 | if (cpu_buffer->nr_pages_to_update <= 0) |
| 1696 | continue; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1697 | /* |
| 1698 | * to add pages, make sure all new pages can be |
| 1699 | * allocated without receiving ENOMEM |
| 1700 | */ |
| 1701 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
| 1702 | if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update, |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1703 | &cpu_buffer->new_pages, cpu)) { |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1704 | /* not enough memory for new pages */ |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1705 | err = -ENOMEM; |
| 1706 | goto out_err; |
| 1707 | } |
| 1708 | } |
| 1709 | |
| 1710 | get_online_cpus(); |
| 1711 | /* |
| 1712 | * Fire off all the required work handlers |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1713 | * We can't schedule on offline CPUs, but it's not necessary |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1714 | * since we can change their buffer sizes without any race. |
| 1715 | */ |
| 1716 | for_each_buffer_cpu(buffer, cpu) { |
| 1717 | cpu_buffer = buffer->buffers[cpu]; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1718 | if (!cpu_buffer->nr_pages_to_update) |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1719 | continue; |
| 1720 | |
Corey Minyard | 021c5b3 | 2014-07-16 14:07:13 -0500 | [diff] [blame] | 1721 | /* Can't run something on an offline CPU. */ |
| 1722 | if (!cpu_online(cpu)) { |
Steven Rostedt (Red Hat) | f5eb558 | 2013-03-07 09:27:42 -0500 | [diff] [blame] | 1723 | rb_update_pages(cpu_buffer); |
| 1724 | cpu_buffer->nr_pages_to_update = 0; |
| 1725 | } else { |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1726 | schedule_work_on(cpu, |
| 1727 | &cpu_buffer->update_pages_work); |
Steven Rostedt (Red Hat) | f5eb558 | 2013-03-07 09:27:42 -0500 | [diff] [blame] | 1728 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1729 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1730 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1731 | /* wait for all the updates to complete */ |
| 1732 | for_each_buffer_cpu(buffer, cpu) { |
| 1733 | cpu_buffer = buffer->buffers[cpu]; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1734 | if (!cpu_buffer->nr_pages_to_update) |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1735 | continue; |
| 1736 | |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1737 | if (cpu_online(cpu)) |
| 1738 | wait_for_completion(&cpu_buffer->update_done); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1739 | cpu_buffer->nr_pages_to_update = 0; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1740 | } |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1741 | |
| 1742 | put_online_cpus(); |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1743 | } else { |
Vaibhav Nagarnaik | 8e49f41 | 2012-10-10 16:40:27 -0700 | [diff] [blame] | 1744 | /* Make sure this CPU has been intitialized */ |
| 1745 | if (!cpumask_test_cpu(cpu_id, buffer->cpumask)) |
| 1746 | goto out; |
| 1747 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1748 | cpu_buffer = buffer->buffers[cpu_id]; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1749 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1750 | if (nr_pages == cpu_buffer->nr_pages) |
| 1751 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1752 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1753 | cpu_buffer->nr_pages_to_update = nr_pages - |
| 1754 | cpu_buffer->nr_pages; |
| 1755 | |
| 1756 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
| 1757 | if (cpu_buffer->nr_pages_to_update > 0 && |
| 1758 | __rb_allocate_pages(cpu_buffer->nr_pages_to_update, |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1759 | &cpu_buffer->new_pages, cpu_id)) { |
| 1760 | err = -ENOMEM; |
| 1761 | goto out_err; |
| 1762 | } |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1763 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1764 | get_online_cpus(); |
| 1765 | |
Corey Minyard | 021c5b3 | 2014-07-16 14:07:13 -0500 | [diff] [blame] | 1766 | /* Can't run something on an offline CPU. */ |
| 1767 | if (!cpu_online(cpu_id)) |
Steven Rostedt (Red Hat) | f5eb558 | 2013-03-07 09:27:42 -0500 | [diff] [blame] | 1768 | rb_update_pages(cpu_buffer); |
| 1769 | else { |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1770 | schedule_work_on(cpu_id, |
| 1771 | &cpu_buffer->update_pages_work); |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1772 | wait_for_completion(&cpu_buffer->update_done); |
Steven Rostedt (Red Hat) | f5eb558 | 2013-03-07 09:27:42 -0500 | [diff] [blame] | 1773 | } |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1774 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1775 | cpu_buffer->nr_pages_to_update = 0; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1776 | put_online_cpus(); |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1777 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1778 | |
| 1779 | out: |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 1780 | /* |
| 1781 | * The ring buffer resize can happen with the ring buffer |
| 1782 | * enabled, so that the update disturbs the tracing as little |
| 1783 | * as possible. But if the buffer is disabled, we do not need |
| 1784 | * to worry about that, and we can take the time to verify |
| 1785 | * that the buffer is not corrupt. |
| 1786 | */ |
| 1787 | if (atomic_read(&buffer->record_disabled)) { |
| 1788 | atomic_inc(&buffer->record_disabled); |
| 1789 | /* |
| 1790 | * Even though the buffer was disabled, we must make sure |
| 1791 | * that it is truly disabled before calling rb_check_pages. |
| 1792 | * There could have been a race between checking |
| 1793 | * record_disable and incrementing it. |
| 1794 | */ |
| 1795 | synchronize_sched(); |
| 1796 | for_each_buffer_cpu(buffer, cpu) { |
| 1797 | cpu_buffer = buffer->buffers[cpu]; |
| 1798 | rb_check_pages(cpu_buffer); |
| 1799 | } |
| 1800 | atomic_dec(&buffer->record_disabled); |
| 1801 | } |
| 1802 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1803 | mutex_unlock(&buffer->mutex); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1804 | return size; |
| 1805 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1806 | out_err: |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1807 | for_each_buffer_cpu(buffer, cpu) { |
| 1808 | struct buffer_page *bpage, *tmp; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1809 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1810 | cpu_buffer = buffer->buffers[cpu]; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1811 | cpu_buffer->nr_pages_to_update = 0; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1812 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1813 | if (list_empty(&cpu_buffer->new_pages)) |
| 1814 | continue; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1815 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1816 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
| 1817 | list) { |
| 1818 | list_del_init(&bpage->list); |
| 1819 | free_buffer_page(bpage); |
| 1820 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1821 | } |
Vegard Nossum | 641d2f6 | 2008-11-18 19:22:13 +0100 | [diff] [blame] | 1822 | mutex_unlock(&buffer->mutex); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1823 | return err; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1824 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1825 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1826 | |
David Sharp | 750912f | 2010-12-08 13:46:47 -0800 | [diff] [blame] | 1827 | void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) |
| 1828 | { |
| 1829 | mutex_lock(&buffer->mutex); |
| 1830 | if (val) |
| 1831 | buffer->flags |= RB_FL_OVERWRITE; |
| 1832 | else |
| 1833 | buffer->flags &= ~RB_FL_OVERWRITE; |
| 1834 | mutex_unlock(&buffer->mutex); |
| 1835 | } |
| 1836 | EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); |
| 1837 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 1838 | static inline void * |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1839 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 1840 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1841 | return bpage->data + index; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 1842 | } |
| 1843 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1844 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1845 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1846 | return bpage->page->data + index; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1847 | } |
| 1848 | |
| 1849 | static inline struct ring_buffer_event * |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1850 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1851 | { |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1852 | return __rb_page_index(cpu_buffer->reader_page, |
| 1853 | cpu_buffer->reader_page->read); |
| 1854 | } |
| 1855 | |
| 1856 | static inline struct ring_buffer_event * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1857 | rb_iter_head_event(struct ring_buffer_iter *iter) |
| 1858 | { |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1859 | return __rb_page_index(iter->head_page, iter->head); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1860 | } |
| 1861 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1862 | static inline unsigned rb_page_commit(struct buffer_page *bpage) |
| 1863 | { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1864 | return local_read(&bpage->page->commit); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1865 | } |
| 1866 | |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 1867 | /* Size is determined by what has been committed */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1868 | static inline unsigned rb_page_size(struct buffer_page *bpage) |
| 1869 | { |
| 1870 | return rb_page_commit(bpage); |
| 1871 | } |
| 1872 | |
| 1873 | static inline unsigned |
| 1874 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) |
| 1875 | { |
| 1876 | return rb_page_commit(cpu_buffer->commit_page); |
| 1877 | } |
| 1878 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1879 | static inline unsigned |
| 1880 | rb_event_index(struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1881 | { |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1882 | unsigned long addr = (unsigned long)event; |
| 1883 | |
Steven Rostedt | 22f470f | 2009-06-11 09:29:58 -0400 | [diff] [blame] | 1884 | return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1885 | } |
| 1886 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1887 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1888 | { |
| 1889 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 1890 | |
| 1891 | /* |
| 1892 | * The iterator could be on the reader page (it starts there). |
| 1893 | * But the head could have moved, since the reader was |
| 1894 | * found. Check for this case and assign the iterator |
| 1895 | * to the head page instead of next. |
| 1896 | */ |
| 1897 | if (iter->head_page == cpu_buffer->reader_page) |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1898 | iter->head_page = rb_set_head_page(cpu_buffer); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1899 | else |
| 1900 | rb_inc_page(cpu_buffer, &iter->head_page); |
| 1901 | |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1902 | iter->read_stamp = iter->head_page->page->time_stamp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1903 | iter->head = 0; |
| 1904 | } |
| 1905 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1906 | /* |
| 1907 | * rb_handle_head_page - writer hit the head page |
| 1908 | * |
| 1909 | * Returns: +1 to retry page |
| 1910 | * 0 to continue |
| 1911 | * -1 on error |
| 1912 | */ |
| 1913 | static int |
| 1914 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, |
| 1915 | struct buffer_page *tail_page, |
| 1916 | struct buffer_page *next_page) |
| 1917 | { |
| 1918 | struct buffer_page *new_head; |
| 1919 | int entries; |
| 1920 | int type; |
| 1921 | int ret; |
| 1922 | |
| 1923 | entries = rb_page_entries(next_page); |
| 1924 | |
| 1925 | /* |
| 1926 | * The hard part is here. We need to move the head |
| 1927 | * forward, and protect against both readers on |
| 1928 | * other CPUs and writers coming in via interrupts. |
| 1929 | */ |
| 1930 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, |
| 1931 | RB_PAGE_HEAD); |
| 1932 | |
| 1933 | /* |
| 1934 | * type can be one of four: |
| 1935 | * NORMAL - an interrupt already moved it for us |
| 1936 | * HEAD - we are the first to get here. |
| 1937 | * UPDATE - we are the interrupt interrupting |
| 1938 | * a current move. |
| 1939 | * MOVED - a reader on another CPU moved the next |
| 1940 | * pointer to its reader page. Give up |
| 1941 | * and try again. |
| 1942 | */ |
| 1943 | |
| 1944 | switch (type) { |
| 1945 | case RB_PAGE_HEAD: |
| 1946 | /* |
| 1947 | * We changed the head to UPDATE, thus |
| 1948 | * it is our responsibility to update |
| 1949 | * the counters. |
| 1950 | */ |
| 1951 | local_add(entries, &cpu_buffer->overrun); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 1952 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1953 | |
| 1954 | /* |
| 1955 | * The entries will be zeroed out when we move the |
| 1956 | * tail page. |
| 1957 | */ |
| 1958 | |
| 1959 | /* still more to do */ |
| 1960 | break; |
| 1961 | |
| 1962 | case RB_PAGE_UPDATE: |
| 1963 | /* |
| 1964 | * This is an interrupt that interrupt the |
| 1965 | * previous update. Still more to do. |
| 1966 | */ |
| 1967 | break; |
| 1968 | case RB_PAGE_NORMAL: |
| 1969 | /* |
| 1970 | * An interrupt came in before the update |
| 1971 | * and processed this for us. |
| 1972 | * Nothing left to do. |
| 1973 | */ |
| 1974 | return 1; |
| 1975 | case RB_PAGE_MOVED: |
| 1976 | /* |
| 1977 | * The reader is on another CPU and just did |
| 1978 | * a swap with our next_page. |
| 1979 | * Try again. |
| 1980 | */ |
| 1981 | return 1; |
| 1982 | default: |
| 1983 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ |
| 1984 | return -1; |
| 1985 | } |
| 1986 | |
| 1987 | /* |
| 1988 | * Now that we are here, the old head pointer is |
| 1989 | * set to UPDATE. This will keep the reader from |
| 1990 | * swapping the head page with the reader page. |
| 1991 | * The reader (on another CPU) will spin till |
| 1992 | * we are finished. |
| 1993 | * |
| 1994 | * We just need to protect against interrupts |
| 1995 | * doing the job. We will set the next pointer |
| 1996 | * to HEAD. After that, we set the old pointer |
| 1997 | * to NORMAL, but only if it was HEAD before. |
| 1998 | * otherwise we are an interrupt, and only |
| 1999 | * want the outer most commit to reset it. |
| 2000 | */ |
| 2001 | new_head = next_page; |
| 2002 | rb_inc_page(cpu_buffer, &new_head); |
| 2003 | |
| 2004 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, |
| 2005 | RB_PAGE_NORMAL); |
| 2006 | |
| 2007 | /* |
| 2008 | * Valid returns are: |
| 2009 | * HEAD - an interrupt came in and already set it. |
| 2010 | * NORMAL - One of two things: |
| 2011 | * 1) We really set it. |
| 2012 | * 2) A bunch of interrupts came in and moved |
| 2013 | * the page forward again. |
| 2014 | */ |
| 2015 | switch (ret) { |
| 2016 | case RB_PAGE_HEAD: |
| 2017 | case RB_PAGE_NORMAL: |
| 2018 | /* OK */ |
| 2019 | break; |
| 2020 | default: |
| 2021 | RB_WARN_ON(cpu_buffer, 1); |
| 2022 | return -1; |
| 2023 | } |
| 2024 | |
| 2025 | /* |
| 2026 | * It is possible that an interrupt came in, |
| 2027 | * set the head up, then more interrupts came in |
| 2028 | * and moved it again. When we get back here, |
| 2029 | * the page would have been set to NORMAL but we |
| 2030 | * just set it back to HEAD. |
| 2031 | * |
| 2032 | * How do you detect this? Well, if that happened |
| 2033 | * the tail page would have moved. |
| 2034 | */ |
| 2035 | if (ret == RB_PAGE_NORMAL) { |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 2036 | struct buffer_page *buffer_tail_page; |
| 2037 | |
| 2038 | buffer_tail_page = READ_ONCE(cpu_buffer->tail_page); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2039 | /* |
| 2040 | * If the tail had moved passed next, then we need |
| 2041 | * to reset the pointer. |
| 2042 | */ |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 2043 | if (buffer_tail_page != tail_page && |
| 2044 | buffer_tail_page != next_page) |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2045 | rb_head_page_set_normal(cpu_buffer, new_head, |
| 2046 | next_page, |
| 2047 | RB_PAGE_HEAD); |
| 2048 | } |
| 2049 | |
| 2050 | /* |
| 2051 | * If this was the outer most commit (the one that |
| 2052 | * changed the original pointer from HEAD to UPDATE), |
| 2053 | * then it is up to us to reset it to NORMAL. |
| 2054 | */ |
| 2055 | if (type == RB_PAGE_HEAD) { |
| 2056 | ret = rb_head_page_set_normal(cpu_buffer, next_page, |
| 2057 | tail_page, |
| 2058 | RB_PAGE_UPDATE); |
| 2059 | if (RB_WARN_ON(cpu_buffer, |
| 2060 | ret != RB_PAGE_UPDATE)) |
| 2061 | return -1; |
| 2062 | } |
| 2063 | |
| 2064 | return 0; |
| 2065 | } |
| 2066 | |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2067 | static inline void |
| 2068 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2069 | unsigned long tail, struct rb_event_info *info) |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2070 | { |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2071 | struct buffer_page *tail_page = info->tail_page; |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2072 | struct ring_buffer_event *event; |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2073 | unsigned long length = info->length; |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2074 | |
| 2075 | /* |
| 2076 | * Only the event that crossed the page boundary |
| 2077 | * must fill the old tail_page with padding. |
| 2078 | */ |
| 2079 | if (tail >= BUF_PAGE_SIZE) { |
Steven Rostedt | b3230c8 | 2010-05-21 11:55:21 -0400 | [diff] [blame] | 2080 | /* |
| 2081 | * If the page was filled, then we still need |
| 2082 | * to update the real_end. Reset it to zero |
| 2083 | * and the reader will ignore it. |
| 2084 | */ |
| 2085 | if (tail == BUF_PAGE_SIZE) |
| 2086 | tail_page->real_end = 0; |
| 2087 | |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2088 | local_sub(length, &tail_page->write); |
| 2089 | return; |
| 2090 | } |
| 2091 | |
| 2092 | event = __rb_page_index(tail_page, tail); |
Linus Torvalds | b0b7065 | 2009-06-20 10:56:46 -0700 | [diff] [blame] | 2093 | kmemcheck_annotate_bitfield(event, bitfield); |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2094 | |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2095 | /* account for padding bytes */ |
| 2096 | local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); |
| 2097 | |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2098 | /* |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 2099 | * Save the original length to the meta data. |
| 2100 | * This will be used by the reader to add lost event |
| 2101 | * counter. |
| 2102 | */ |
| 2103 | tail_page->real_end = tail; |
| 2104 | |
| 2105 | /* |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2106 | * If this event is bigger than the minimum size, then |
| 2107 | * we need to be careful that we don't subtract the |
| 2108 | * write counter enough to allow another writer to slip |
| 2109 | * in on this page. |
| 2110 | * We put in a discarded commit instead, to make sure |
| 2111 | * that this space is not used again. |
| 2112 | * |
| 2113 | * If we are less than the minimum size, we don't need to |
| 2114 | * worry about it. |
| 2115 | */ |
| 2116 | if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) { |
| 2117 | /* No room for any events */ |
| 2118 | |
| 2119 | /* Mark the rest of the page with padding */ |
| 2120 | rb_event_set_padding(event); |
| 2121 | |
| 2122 | /* Set the write back to the previous setting */ |
| 2123 | local_sub(length, &tail_page->write); |
| 2124 | return; |
| 2125 | } |
| 2126 | |
| 2127 | /* Put in a discarded event */ |
| 2128 | event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE; |
| 2129 | event->type_len = RINGBUF_TYPE_PADDING; |
| 2130 | /* time delta must be non zero */ |
| 2131 | event->time_delta = 1; |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2132 | |
| 2133 | /* Set write to end of buffer */ |
| 2134 | length = (tail + length) - BUF_PAGE_SIZE; |
| 2135 | local_sub(length, &tail_page->write); |
| 2136 | } |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2137 | |
Steven Rostedt (Red Hat) | 4239c38 | 2015-11-17 16:36:06 -0500 | [diff] [blame] | 2138 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer); |
| 2139 | |
Steven Rostedt | 747e94a | 2010-10-08 13:51:48 -0400 | [diff] [blame] | 2140 | /* |
| 2141 | * This is the slow path, force gcc not to inline it. |
| 2142 | */ |
| 2143 | static noinline struct ring_buffer_event * |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2144 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2145 | unsigned long tail, struct rb_event_info *info) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2146 | { |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2147 | struct buffer_page *tail_page = info->tail_page; |
Steven Rostedt | 5a50e33 | 2009-11-17 08:43:01 -0500 | [diff] [blame] | 2148 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2149 | struct ring_buffer *buffer = cpu_buffer->buffer; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2150 | struct buffer_page *next_page; |
| 2151 | int ret; |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2152 | |
| 2153 | next_page = tail_page; |
| 2154 | |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2155 | rb_inc_page(cpu_buffer, &next_page); |
| 2156 | |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2157 | /* |
| 2158 | * If for some reason, we had an interrupt storm that made |
| 2159 | * it all the way around the buffer, bail, and warn |
| 2160 | * about it. |
| 2161 | */ |
| 2162 | if (unlikely(next_page == commit_page)) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2163 | local_inc(&cpu_buffer->commit_overrun); |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2164 | goto out_reset; |
| 2165 | } |
| 2166 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2167 | /* |
| 2168 | * This is where the fun begins! |
| 2169 | * |
| 2170 | * We are fighting against races between a reader that |
| 2171 | * could be on another CPU trying to swap its reader |
| 2172 | * page with the buffer head. |
| 2173 | * |
| 2174 | * We are also fighting against interrupts coming in and |
| 2175 | * moving the head or tail on us as well. |
| 2176 | * |
| 2177 | * If the next page is the head page then we have filled |
| 2178 | * the buffer, unless the commit page is still on the |
| 2179 | * reader page. |
| 2180 | */ |
| 2181 | if (rb_is_head_page(cpu_buffer, next_page, &tail_page->list)) { |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2182 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2183 | /* |
| 2184 | * If the commit is not on the reader page, then |
| 2185 | * move the header page. |
| 2186 | */ |
| 2187 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { |
| 2188 | /* |
| 2189 | * If we are not in overwrite mode, |
| 2190 | * this is easy, just stop here. |
| 2191 | */ |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 2192 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
| 2193 | local_inc(&cpu_buffer->dropped_events); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2194 | goto out_reset; |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 2195 | } |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2196 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2197 | ret = rb_handle_head_page(cpu_buffer, |
| 2198 | tail_page, |
| 2199 | next_page); |
| 2200 | if (ret < 0) |
| 2201 | goto out_reset; |
| 2202 | if (ret) |
| 2203 | goto out_again; |
| 2204 | } else { |
| 2205 | /* |
| 2206 | * We need to be careful here too. The |
| 2207 | * commit page could still be on the reader |
| 2208 | * page. We could have a small buffer, and |
| 2209 | * have filled up the buffer with events |
| 2210 | * from interrupts and such, and wrapped. |
| 2211 | * |
| 2212 | * Note, if the tail page is also the on the |
| 2213 | * reader_page, we let it move out. |
| 2214 | */ |
| 2215 | if (unlikely((cpu_buffer->commit_page != |
| 2216 | cpu_buffer->tail_page) && |
| 2217 | (cpu_buffer->commit_page == |
| 2218 | cpu_buffer->reader_page))) { |
| 2219 | local_inc(&cpu_buffer->commit_overrun); |
| 2220 | goto out_reset; |
| 2221 | } |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2222 | } |
| 2223 | } |
| 2224 | |
Steven Rostedt (Red Hat) | 7000498 | 2015-11-17 15:15:19 -0500 | [diff] [blame] | 2225 | rb_tail_page_update(cpu_buffer, tail_page, next_page); |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2226 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2227 | out_again: |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2228 | |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2229 | rb_reset_tail(cpu_buffer, tail, info); |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2230 | |
Steven Rostedt (Red Hat) | 4239c38 | 2015-11-17 16:36:06 -0500 | [diff] [blame] | 2231 | /* Commit what we have for now. */ |
| 2232 | rb_end_commit(cpu_buffer); |
| 2233 | /* rb_end_commit() decs committing */ |
| 2234 | local_inc(&cpu_buffer->committing); |
| 2235 | |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2236 | /* fail and let the caller try again */ |
| 2237 | return ERR_PTR(-EAGAIN); |
| 2238 | |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 2239 | out_reset: |
Lai Jiangshan | 6f3b344 | 2009-01-12 11:06:18 +0800 | [diff] [blame] | 2240 | /* reset write */ |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2241 | rb_reset_tail(cpu_buffer, tail, info); |
Lai Jiangshan | 6f3b344 | 2009-01-12 11:06:18 +0800 | [diff] [blame] | 2242 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2243 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2244 | } |
| 2245 | |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2246 | /* Slow path, do not inline */ |
| 2247 | static noinline struct ring_buffer_event * |
| 2248 | rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) |
| 2249 | { |
| 2250 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; |
| 2251 | |
| 2252 | /* Not the first event on the page? */ |
| 2253 | if (rb_event_index(event)) { |
| 2254 | event->time_delta = delta & TS_MASK; |
| 2255 | event->array[0] = delta >> TS_SHIFT; |
| 2256 | } else { |
| 2257 | /* nope, just zero it */ |
| 2258 | event->time_delta = 0; |
| 2259 | event->array[0] = 0; |
| 2260 | } |
| 2261 | |
| 2262 | return skip_time_extend(event); |
| 2263 | } |
| 2264 | |
Yaowei Bai | cdb2a0a | 2015-09-29 22:43:34 +0800 | [diff] [blame] | 2265 | static inline bool rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2266 | struct ring_buffer_event *event); |
| 2267 | |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2268 | /** |
| 2269 | * rb_update_event - update event type and data |
| 2270 | * @event: the event to update |
| 2271 | * @type: the type of event |
| 2272 | * @length: the size of the event field in the ring buffer |
| 2273 | * |
| 2274 | * Update the type and data fields of the event. The length |
| 2275 | * is the actual size that is written to the ring buffer, |
| 2276 | * and with this, we can determine what to place into the |
| 2277 | * data field. |
| 2278 | */ |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2279 | static void |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2280 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
| 2281 | struct ring_buffer_event *event, |
| 2282 | struct rb_event_info *info) |
| 2283 | { |
| 2284 | unsigned length = info->length; |
| 2285 | u64 delta = info->delta; |
| 2286 | |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2287 | /* Only a commit updates the timestamp */ |
| 2288 | if (unlikely(!rb_event_is_commit(cpu_buffer, event))) |
| 2289 | delta = 0; |
| 2290 | |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2291 | /* |
| 2292 | * If we need to add a timestamp, then we |
| 2293 | * add it to the start of the resevered space. |
| 2294 | */ |
| 2295 | if (unlikely(info->add_timestamp)) { |
| 2296 | event = rb_add_time_stamp(event, delta); |
| 2297 | length -= RB_LEN_TIME_EXTEND; |
| 2298 | delta = 0; |
| 2299 | } |
| 2300 | |
| 2301 | event->time_delta = delta; |
| 2302 | length -= RB_EVNT_HDR_SIZE; |
| 2303 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { |
| 2304 | event->type_len = 0; |
| 2305 | event->array[0] = length; |
| 2306 | } else |
| 2307 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); |
| 2308 | } |
| 2309 | |
| 2310 | static unsigned rb_calculate_event_length(unsigned length) |
| 2311 | { |
| 2312 | struct ring_buffer_event event; /* Used only for sizeof array */ |
| 2313 | |
| 2314 | /* zero length can cause confusions */ |
| 2315 | if (!length) |
| 2316 | length++; |
| 2317 | |
| 2318 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) |
| 2319 | length += sizeof(event.array[0]); |
| 2320 | |
| 2321 | length += RB_EVNT_HDR_SIZE; |
| 2322 | length = ALIGN(length, RB_ARCH_ALIGNMENT); |
| 2323 | |
| 2324 | /* |
| 2325 | * In case the time delta is larger than the 27 bits for it |
| 2326 | * in the header, we need to add a timestamp. If another |
| 2327 | * event comes in when trying to discard this one to increase |
| 2328 | * the length, then the timestamp will be added in the allocated |
| 2329 | * space of this event. If length is bigger than the size needed |
| 2330 | * for the TIME_EXTEND, then padding has to be used. The events |
| 2331 | * length must be either RB_LEN_TIME_EXTEND, or greater than or equal |
| 2332 | * to RB_LEN_TIME_EXTEND + 8, as 8 is the minimum size for padding. |
| 2333 | * As length is a multiple of 4, we only need to worry if it |
| 2334 | * is 12 (RB_LEN_TIME_EXTEND + 4). |
| 2335 | */ |
| 2336 | if (length == RB_LEN_TIME_EXTEND + RB_ALIGNMENT) |
| 2337 | length += RB_ALIGNMENT; |
| 2338 | |
| 2339 | return length; |
| 2340 | } |
| 2341 | |
Steven Rostedt (Red Hat) | 9826b27 | 2015-05-28 17:36:45 -0400 | [diff] [blame] | 2342 | #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
| 2343 | static inline bool sched_clock_stable(void) |
| 2344 | { |
| 2345 | return true; |
| 2346 | } |
| 2347 | #endif |
| 2348 | |
Steven Rostedt (Red Hat) | a4543a2 | 2015-05-29 09:40:18 -0400 | [diff] [blame] | 2349 | static inline int |
| 2350 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2351 | struct ring_buffer_event *event) |
| 2352 | { |
| 2353 | unsigned long new_index, old_index; |
| 2354 | struct buffer_page *bpage; |
| 2355 | unsigned long index; |
| 2356 | unsigned long addr; |
| 2357 | |
| 2358 | new_index = rb_event_index(event); |
| 2359 | old_index = new_index + rb_event_ts_length(event); |
| 2360 | addr = (unsigned long)event; |
| 2361 | addr &= PAGE_MASK; |
| 2362 | |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 2363 | bpage = READ_ONCE(cpu_buffer->tail_page); |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2364 | |
| 2365 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { |
| 2366 | unsigned long write_mask = |
| 2367 | local_read(&bpage->write) & ~RB_WRITE_MASK; |
| 2368 | unsigned long event_length = rb_event_length(event); |
| 2369 | /* |
| 2370 | * This is on the tail page. It is possible that |
| 2371 | * a write could come in and move the tail page |
| 2372 | * and write to the next page. That is fine |
| 2373 | * because we just shorten what is on this page. |
| 2374 | */ |
| 2375 | old_index += write_mask; |
| 2376 | new_index += write_mask; |
| 2377 | index = local_cmpxchg(&bpage->write, old_index, new_index); |
| 2378 | if (index == old_index) { |
| 2379 | /* update counters */ |
| 2380 | local_sub(event_length, &cpu_buffer->entries_bytes); |
| 2381 | return 1; |
| 2382 | } |
| 2383 | } |
| 2384 | |
| 2385 | /* could not discard */ |
| 2386 | return 0; |
| 2387 | } |
| 2388 | |
| 2389 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) |
| 2390 | { |
| 2391 | local_inc(&cpu_buffer->committing); |
| 2392 | local_inc(&cpu_buffer->commits); |
| 2393 | } |
| 2394 | |
| 2395 | static void |
| 2396 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
| 2397 | { |
| 2398 | unsigned long max_count; |
| 2399 | |
| 2400 | /* |
| 2401 | * We only race with interrupts and NMIs on this CPU. |
| 2402 | * If we own the commit event, then we can commit |
| 2403 | * all others that interrupted us, since the interruptions |
| 2404 | * are in stack format (they finish before they come |
| 2405 | * back to us). This allows us to do a simple loop to |
| 2406 | * assign the commit to the tail. |
| 2407 | */ |
| 2408 | again: |
| 2409 | max_count = cpu_buffer->nr_pages * 100; |
| 2410 | |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 2411 | while (cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page)) { |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2412 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
| 2413 | return; |
| 2414 | if (RB_WARN_ON(cpu_buffer, |
| 2415 | rb_is_reader_page(cpu_buffer->tail_page))) |
| 2416 | return; |
| 2417 | local_set(&cpu_buffer->commit_page->page->commit, |
| 2418 | rb_page_write(cpu_buffer->commit_page)); |
| 2419 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); |
Steven Rostedt (Red Hat) | 7000498 | 2015-11-17 15:15:19 -0500 | [diff] [blame] | 2420 | /* Only update the write stamp if the page has an event */ |
| 2421 | if (rb_page_write(cpu_buffer->commit_page)) |
| 2422 | cpu_buffer->write_stamp = |
| 2423 | cpu_buffer->commit_page->page->time_stamp; |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2424 | /* add barrier to keep gcc from optimizing too much */ |
| 2425 | barrier(); |
| 2426 | } |
| 2427 | while (rb_commit_index(cpu_buffer) != |
| 2428 | rb_page_write(cpu_buffer->commit_page)) { |
| 2429 | |
| 2430 | local_set(&cpu_buffer->commit_page->page->commit, |
| 2431 | rb_page_write(cpu_buffer->commit_page)); |
| 2432 | RB_WARN_ON(cpu_buffer, |
| 2433 | local_read(&cpu_buffer->commit_page->page->commit) & |
| 2434 | ~RB_WRITE_MASK); |
| 2435 | barrier(); |
| 2436 | } |
| 2437 | |
| 2438 | /* again, keep gcc from optimizing */ |
| 2439 | barrier(); |
| 2440 | |
| 2441 | /* |
| 2442 | * If an interrupt came in just after the first while loop |
| 2443 | * and pushed the tail page forward, we will be left with |
| 2444 | * a dangling commit that will never go forward. |
| 2445 | */ |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 2446 | if (unlikely(cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page))) |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2447 | goto again; |
| 2448 | } |
| 2449 | |
| 2450 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
| 2451 | { |
| 2452 | unsigned long commits; |
| 2453 | |
| 2454 | if (RB_WARN_ON(cpu_buffer, |
| 2455 | !local_read(&cpu_buffer->committing))) |
| 2456 | return; |
| 2457 | |
| 2458 | again: |
| 2459 | commits = local_read(&cpu_buffer->commits); |
| 2460 | /* synchronize with interrupts */ |
| 2461 | barrier(); |
| 2462 | if (local_read(&cpu_buffer->committing) == 1) |
| 2463 | rb_set_commit_to_write(cpu_buffer); |
| 2464 | |
| 2465 | local_dec(&cpu_buffer->committing); |
| 2466 | |
| 2467 | /* synchronize with interrupts */ |
| 2468 | barrier(); |
| 2469 | |
| 2470 | /* |
| 2471 | * Need to account for interrupts coming in between the |
| 2472 | * updating of the commit page and the clearing of the |
| 2473 | * committing counter. |
| 2474 | */ |
| 2475 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && |
| 2476 | !local_read(&cpu_buffer->committing)) { |
| 2477 | local_inc(&cpu_buffer->committing); |
| 2478 | goto again; |
| 2479 | } |
| 2480 | } |
| 2481 | |
| 2482 | static inline void rb_event_discard(struct ring_buffer_event *event) |
| 2483 | { |
| 2484 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
| 2485 | event = skip_time_extend(event); |
| 2486 | |
| 2487 | /* array[0] holds the actual length for the discarded event */ |
| 2488 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; |
| 2489 | event->type_len = RINGBUF_TYPE_PADDING; |
| 2490 | /* time delta must be non zero */ |
| 2491 | if (!event->time_delta) |
| 2492 | event->time_delta = 1; |
| 2493 | } |
| 2494 | |
Yaowei Bai | cdb2a0a | 2015-09-29 22:43:34 +0800 | [diff] [blame] | 2495 | static inline bool |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2496 | rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
| 2497 | struct ring_buffer_event *event) |
| 2498 | { |
| 2499 | unsigned long addr = (unsigned long)event; |
| 2500 | unsigned long index; |
| 2501 | |
| 2502 | index = rb_event_index(event); |
| 2503 | addr &= PAGE_MASK; |
| 2504 | |
| 2505 | return cpu_buffer->commit_page->page == (void *)addr && |
| 2506 | rb_commit_index(cpu_buffer) == index; |
| 2507 | } |
| 2508 | |
Steven Rostedt (Red Hat) | a4543a2 | 2015-05-29 09:40:18 -0400 | [diff] [blame] | 2509 | static void |
| 2510 | rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | d90fd77 | 2015-05-29 12:12:27 -0400 | [diff] [blame] | 2511 | struct ring_buffer_event *event) |
| 2512 | { |
| 2513 | u64 delta; |
| 2514 | |
| 2515 | /* |
| 2516 | * The event first in the commit queue updates the |
| 2517 | * time stamp. |
| 2518 | */ |
| 2519 | if (rb_event_is_commit(cpu_buffer, event)) { |
| 2520 | /* |
| 2521 | * A commit event that is first on a page |
| 2522 | * updates the write timestamp with the page stamp |
| 2523 | */ |
| 2524 | if (!rb_event_index(event)) |
| 2525 | cpu_buffer->write_stamp = |
| 2526 | cpu_buffer->commit_page->page->time_stamp; |
| 2527 | else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { |
| 2528 | delta = event->array[0]; |
| 2529 | delta <<= TS_SHIFT; |
| 2530 | delta += event->time_delta; |
| 2531 | cpu_buffer->write_stamp += delta; |
| 2532 | } else |
| 2533 | cpu_buffer->write_stamp += event->time_delta; |
| 2534 | } |
| 2535 | } |
| 2536 | |
| 2537 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, |
| 2538 | struct ring_buffer_event *event) |
| 2539 | { |
| 2540 | local_inc(&cpu_buffer->entries); |
| 2541 | rb_update_write_stamp(cpu_buffer, event); |
| 2542 | rb_end_commit(cpu_buffer); |
| 2543 | } |
| 2544 | |
| 2545 | static __always_inline void |
| 2546 | rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) |
| 2547 | { |
| 2548 | bool pagebusy; |
| 2549 | |
| 2550 | if (buffer->irq_work.waiters_pending) { |
| 2551 | buffer->irq_work.waiters_pending = false; |
| 2552 | /* irq_work_queue() supplies it's own memory barriers */ |
| 2553 | irq_work_queue(&buffer->irq_work.work); |
| 2554 | } |
| 2555 | |
| 2556 | if (cpu_buffer->irq_work.waiters_pending) { |
| 2557 | cpu_buffer->irq_work.waiters_pending = false; |
| 2558 | /* irq_work_queue() supplies it's own memory barriers */ |
| 2559 | irq_work_queue(&cpu_buffer->irq_work.work); |
| 2560 | } |
| 2561 | |
| 2562 | pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; |
| 2563 | |
| 2564 | if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) { |
| 2565 | cpu_buffer->irq_work.wakeup_full = true; |
| 2566 | cpu_buffer->irq_work.full_waiters_pending = false; |
| 2567 | /* irq_work_queue() supplies it's own memory barriers */ |
| 2568 | irq_work_queue(&cpu_buffer->irq_work.work); |
| 2569 | } |
| 2570 | } |
| 2571 | |
| 2572 | /* |
| 2573 | * The lock and unlock are done within a preempt disable section. |
| 2574 | * The current_context per_cpu variable can only be modified |
| 2575 | * by the current task between lock and unlock. But it can |
| 2576 | * be modified more than once via an interrupt. To pass this |
| 2577 | * information from the lock to the unlock without having to |
| 2578 | * access the 'in_interrupt()' functions again (which do show |
| 2579 | * a bit of overhead in something as critical as function tracing, |
| 2580 | * we use a bitmask trick. |
| 2581 | * |
| 2582 | * bit 0 = NMI context |
| 2583 | * bit 1 = IRQ context |
| 2584 | * bit 2 = SoftIRQ context |
| 2585 | * bit 3 = normal context. |
| 2586 | * |
| 2587 | * This works because this is the order of contexts that can |
| 2588 | * preempt other contexts. A SoftIRQ never preempts an IRQ |
| 2589 | * context. |
| 2590 | * |
| 2591 | * When the context is determined, the corresponding bit is |
| 2592 | * checked and set (if it was set, then a recursion of that context |
| 2593 | * happened). |
| 2594 | * |
| 2595 | * On unlock, we need to clear this bit. To do so, just subtract |
| 2596 | * 1 from the current_context and AND it to itself. |
| 2597 | * |
| 2598 | * (binary) |
| 2599 | * 101 - 1 = 100 |
| 2600 | * 101 & 100 = 100 (clearing bit zero) |
| 2601 | * |
| 2602 | * 1010 - 1 = 1001 |
| 2603 | * 1010 & 1001 = 1000 (clearing bit 1) |
| 2604 | * |
| 2605 | * The least significant bit can be cleared this way, and it |
| 2606 | * just so happens that it is the same bit corresponding to |
| 2607 | * the current context. |
| 2608 | */ |
| 2609 | |
| 2610 | static __always_inline int |
| 2611 | trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) |
| 2612 | { |
| 2613 | unsigned int val = cpu_buffer->current_context; |
| 2614 | int bit; |
| 2615 | |
| 2616 | if (in_interrupt()) { |
| 2617 | if (in_nmi()) |
| 2618 | bit = RB_CTX_NMI; |
| 2619 | else if (in_irq()) |
| 2620 | bit = RB_CTX_IRQ; |
| 2621 | else |
| 2622 | bit = RB_CTX_SOFTIRQ; |
| 2623 | } else |
| 2624 | bit = RB_CTX_NORMAL; |
| 2625 | |
| 2626 | if (unlikely(val & (1 << bit))) |
| 2627 | return 1; |
| 2628 | |
| 2629 | val |= (1 << bit); |
| 2630 | cpu_buffer->current_context = val; |
| 2631 | |
| 2632 | return 0; |
| 2633 | } |
| 2634 | |
| 2635 | static __always_inline void |
| 2636 | trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer) |
| 2637 | { |
| 2638 | cpu_buffer->current_context &= cpu_buffer->current_context - 1; |
| 2639 | } |
| 2640 | |
| 2641 | /** |
| 2642 | * ring_buffer_unlock_commit - commit a reserved |
| 2643 | * @buffer: The buffer to commit to |
| 2644 | * @event: The event pointer to commit. |
| 2645 | * |
| 2646 | * This commits the data to the ring buffer, and releases any locks held. |
| 2647 | * |
| 2648 | * Must be paired with ring_buffer_lock_reserve. |
| 2649 | */ |
| 2650 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, |
| 2651 | struct ring_buffer_event *event) |
| 2652 | { |
| 2653 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2654 | int cpu = raw_smp_processor_id(); |
| 2655 | |
| 2656 | cpu_buffer = buffer->buffers[cpu]; |
| 2657 | |
| 2658 | rb_commit(cpu_buffer, event); |
| 2659 | |
| 2660 | rb_wakeups(buffer, cpu_buffer); |
| 2661 | |
| 2662 | trace_recursive_unlock(cpu_buffer); |
| 2663 | |
| 2664 | preempt_enable_notrace(); |
| 2665 | |
| 2666 | return 0; |
| 2667 | } |
| 2668 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
Steven Rostedt (Red Hat) | a4543a2 | 2015-05-29 09:40:18 -0400 | [diff] [blame] | 2669 | |
Steven Rostedt (Red Hat) | 9826b27 | 2015-05-28 17:36:45 -0400 | [diff] [blame] | 2670 | static noinline void |
| 2671 | rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer, |
| 2672 | struct rb_event_info *info) |
| 2673 | { |
| 2674 | WARN_ONCE(info->delta > (1ULL << 59), |
| 2675 | KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", |
| 2676 | (unsigned long long)info->delta, |
| 2677 | (unsigned long long)info->ts, |
| 2678 | (unsigned long long)cpu_buffer->write_stamp, |
| 2679 | sched_clock_stable() ? "" : |
| 2680 | "If you just came from a suspend/resume,\n" |
| 2681 | "please switch to the trace global clock:\n" |
| 2682 | " echo global > /sys/kernel/debug/tracing/trace_clock\n"); |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2683 | info->add_timestamp = 1; |
Steven Rostedt (Red Hat) | 9826b27 | 2015-05-28 17:36:45 -0400 | [diff] [blame] | 2684 | } |
| 2685 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2686 | static struct ring_buffer_event * |
| 2687 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2688 | struct rb_event_info *info) |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2689 | { |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2690 | struct ring_buffer_event *event; |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2691 | struct buffer_page *tail_page; |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2692 | unsigned long tail, write; |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2693 | |
| 2694 | /* |
| 2695 | * If the time delta since the last event is too big to |
| 2696 | * hold in the time field of the event, then we append a |
| 2697 | * TIME EXTEND event ahead of the data event. |
| 2698 | */ |
| 2699 | if (unlikely(info->add_timestamp)) |
| 2700 | info->length += RB_LEN_TIME_EXTEND; |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2701 | |
Steven Rostedt (Red Hat) | 8573636 | 2015-11-17 14:03:11 -0500 | [diff] [blame] | 2702 | /* Don't let the compiler play games with cpu_buffer->tail_page */ |
| 2703 | tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page); |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2704 | write = local_add_return(info->length, &tail_page->write); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2705 | |
| 2706 | /* set write to only the index of the write */ |
| 2707 | write &= RB_WRITE_MASK; |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2708 | tail = write - info->length; |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2709 | |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2710 | /* |
| 2711 | * If this is the first commit on the page, then it has the same |
| 2712 | * timestamp as the page itself. |
| 2713 | */ |
| 2714 | if (!tail) |
| 2715 | info->delta = 0; |
| 2716 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2717 | /* See if we shot pass the end of this buffer page */ |
Steven Rostedt | 747e94a | 2010-10-08 13:51:48 -0400 | [diff] [blame] | 2718 | if (unlikely(write > BUF_PAGE_SIZE)) |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2719 | return rb_move_tail(cpu_buffer, tail, info); |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2720 | |
| 2721 | /* We reserved something on the buffer */ |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2722 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2723 | event = __rb_page_index(tail_page, tail); |
Vegard Nossum | 1744a21 | 2009-02-28 08:29:44 +0100 | [diff] [blame] | 2724 | kmemcheck_annotate_bitfield(event, bitfield); |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2725 | rb_update_event(cpu_buffer, event, info); |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2726 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2727 | local_inc(&tail_page->entries); |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2728 | |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2729 | /* |
| 2730 | * If this is the first commit on the page, then update |
| 2731 | * its timestamp. |
| 2732 | */ |
| 2733 | if (!tail) |
| 2734 | tail_page->page->time_stamp = info->ts; |
| 2735 | |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2736 | /* account for these added bytes */ |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2737 | local_add(info->length, &cpu_buffer->entries_bytes); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2738 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2739 | return event; |
| 2740 | } |
| 2741 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2742 | static struct ring_buffer_event * |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2743 | rb_reserve_next_event(struct ring_buffer *buffer, |
| 2744 | struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt | 1cd8d73 | 2009-05-11 14:08:09 -0400 | [diff] [blame] | 2745 | unsigned long length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2746 | { |
| 2747 | struct ring_buffer_event *event; |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2748 | struct rb_event_info info; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2749 | int nr_loops = 0; |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2750 | u64 diff; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2751 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2752 | rb_start_commit(cpu_buffer); |
| 2753 | |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 2754 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2755 | /* |
| 2756 | * Due to the ability to swap a cpu buffer from a buffer |
| 2757 | * it is possible it was swapped before we committed. |
| 2758 | * (committing stops a swap). We check for it here and |
| 2759 | * if it happened, we have to fail the write. |
| 2760 | */ |
| 2761 | barrier(); |
| 2762 | if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { |
| 2763 | local_dec(&cpu_buffer->committing); |
| 2764 | local_dec(&cpu_buffer->commits); |
| 2765 | return NULL; |
| 2766 | } |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 2767 | #endif |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2768 | |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2769 | info.length = rb_calculate_event_length(length); |
Steven Rostedt (Red Hat) | a4543a2 | 2015-05-29 09:40:18 -0400 | [diff] [blame] | 2770 | again: |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2771 | info.add_timestamp = 0; |
| 2772 | info.delta = 0; |
| 2773 | |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2774 | /* |
| 2775 | * We allow for interrupts to reenter here and do a trace. |
| 2776 | * If one does, it will cause this original code to loop |
| 2777 | * back here. Even with heavy interrupts happening, this |
| 2778 | * should only happen a few times in a row. If this happens |
| 2779 | * 1000 times in a row, there must be either an interrupt |
| 2780 | * storm or we have something buggy. |
| 2781 | * Bail! |
| 2782 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 2783 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2784 | goto out_fail; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2785 | |
Steven Rostedt (Red Hat) | b7dc42f | 2015-09-03 08:57:12 -0400 | [diff] [blame] | 2786 | info.ts = rb_time_stamp(cpu_buffer->buffer); |
| 2787 | diff = info.ts - cpu_buffer->write_stamp; |
| 2788 | |
| 2789 | /* make sure this diff is calculated here */ |
| 2790 | barrier(); |
| 2791 | |
| 2792 | /* Did the write stamp get updated already? */ |
| 2793 | if (likely(info.ts >= cpu_buffer->write_stamp)) { |
| 2794 | info.delta = diff; |
| 2795 | if (unlikely(test_time_stamp(info.delta))) |
| 2796 | rb_handle_timestamp(cpu_buffer, &info); |
| 2797 | } |
| 2798 | |
Steven Rostedt (Red Hat) | fcc742e | 2015-05-28 17:13:14 -0400 | [diff] [blame] | 2799 | event = __rb_reserve_next(cpu_buffer, &info); |
| 2800 | |
Steven Rostedt (Red Hat) | bd1b7cd | 2015-11-23 17:35:24 -0500 | [diff] [blame] | 2801 | if (unlikely(PTR_ERR(event) == -EAGAIN)) { |
| 2802 | if (info.add_timestamp) |
| 2803 | info.length -= RB_LEN_TIME_EXTEND; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2804 | goto again; |
Steven Rostedt (Red Hat) | bd1b7cd | 2015-11-23 17:35:24 -0500 | [diff] [blame] | 2805 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2806 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2807 | if (!event) |
| 2808 | goto out_fail; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2809 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2810 | return event; |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2811 | |
| 2812 | out_fail: |
| 2813 | rb_end_commit(cpu_buffer); |
| 2814 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2815 | } |
| 2816 | |
| 2817 | /** |
| 2818 | * ring_buffer_lock_reserve - reserve a part of the buffer |
| 2819 | * @buffer: the ring buffer to reserve from |
| 2820 | * @length: the length of the data to reserve (excluding event header) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2821 | * |
| 2822 | * Returns a reseverd event on the ring buffer to copy directly to. |
| 2823 | * The user of this interface will need to get the body to write into |
| 2824 | * and can use the ring_buffer_event_data() interface. |
| 2825 | * |
| 2826 | * The length is the length of the data needed, not the event length |
| 2827 | * which also includes the event header. |
| 2828 | * |
| 2829 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. |
| 2830 | * If NULL is returned, then nothing has been allocated or locked. |
| 2831 | */ |
| 2832 | struct ring_buffer_event * |
Arnaldo Carvalho de Melo | 0a98775 | 2009-02-05 16:12:56 -0200 | [diff] [blame] | 2833 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2834 | { |
| 2835 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2836 | struct ring_buffer_event *event; |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2837 | int cpu; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2838 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2839 | /* If we are tracing schedule, we don't want to recurse */ |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2840 | preempt_disable_notrace(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2841 | |
Steven Rostedt (Red Hat) | 3205f80 | 2015-05-21 17:39:29 -0400 | [diff] [blame] | 2842 | if (unlikely(atomic_read(&buffer->record_disabled))) |
Steven Rostedt (Red Hat) | 58a09ec | 2015-05-27 10:27:47 -0400 | [diff] [blame] | 2843 | goto out; |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2844 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2845 | cpu = raw_smp_processor_id(); |
| 2846 | |
Steven Rostedt (Red Hat) | 3205f80 | 2015-05-21 17:39:29 -0400 | [diff] [blame] | 2847 | if (unlikely(!cpumask_test_cpu(cpu, buffer->cpumask))) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2848 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2849 | |
| 2850 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2851 | |
Steven Rostedt (Red Hat) | 3205f80 | 2015-05-21 17:39:29 -0400 | [diff] [blame] | 2852 | if (unlikely(atomic_read(&cpu_buffer->record_disabled))) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2853 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2854 | |
Steven Rostedt (Red Hat) | 3205f80 | 2015-05-21 17:39:29 -0400 | [diff] [blame] | 2855 | if (unlikely(length > BUF_MAX_DATA_SIZE)) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2856 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2857 | |
Steven Rostedt (Red Hat) | 58a09ec | 2015-05-27 10:27:47 -0400 | [diff] [blame] | 2858 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
| 2859 | goto out; |
| 2860 | |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2861 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2862 | if (!event) |
Steven Rostedt (Red Hat) | 58a09ec | 2015-05-27 10:27:47 -0400 | [diff] [blame] | 2863 | goto out_unlock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2864 | |
| 2865 | return event; |
| 2866 | |
Steven Rostedt (Red Hat) | 58a09ec | 2015-05-27 10:27:47 -0400 | [diff] [blame] | 2867 | out_unlock: |
| 2868 | trace_recursive_unlock(cpu_buffer); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2869 | out: |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2870 | preempt_enable_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2871 | return NULL; |
| 2872 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2873 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2874 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2875 | /* |
| 2876 | * Decrement the entries to the page that an event is on. |
| 2877 | * The event does not even need to exist, only the pointer |
| 2878 | * to the page it is on. This may only be called before the commit |
| 2879 | * takes place. |
| 2880 | */ |
| 2881 | static inline void |
| 2882 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, |
| 2883 | struct ring_buffer_event *event) |
| 2884 | { |
| 2885 | unsigned long addr = (unsigned long)event; |
| 2886 | struct buffer_page *bpage = cpu_buffer->commit_page; |
| 2887 | struct buffer_page *start; |
| 2888 | |
| 2889 | addr &= PAGE_MASK; |
| 2890 | |
| 2891 | /* Do the likely case first */ |
| 2892 | if (likely(bpage->page == (void *)addr)) { |
| 2893 | local_dec(&bpage->entries); |
| 2894 | return; |
| 2895 | } |
| 2896 | |
| 2897 | /* |
| 2898 | * Because the commit page may be on the reader page we |
| 2899 | * start with the next page and check the end loop there. |
| 2900 | */ |
| 2901 | rb_inc_page(cpu_buffer, &bpage); |
| 2902 | start = bpage; |
| 2903 | do { |
| 2904 | if (bpage->page == (void *)addr) { |
| 2905 | local_dec(&bpage->entries); |
| 2906 | return; |
| 2907 | } |
| 2908 | rb_inc_page(cpu_buffer, &bpage); |
| 2909 | } while (bpage != start); |
| 2910 | |
| 2911 | /* commit not part of this buffer?? */ |
| 2912 | RB_WARN_ON(cpu_buffer, 1); |
| 2913 | } |
| 2914 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2915 | /** |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2916 | * ring_buffer_commit_discard - discard an event that has not been committed |
| 2917 | * @buffer: the ring buffer |
| 2918 | * @event: non committed event to discard |
| 2919 | * |
Steven Rostedt | dc892f7 | 2009-09-03 15:33:41 -0400 | [diff] [blame] | 2920 | * Sometimes an event that is in the ring buffer needs to be ignored. |
| 2921 | * This function lets the user discard an event in the ring buffer |
| 2922 | * and then that event will not be read later. |
| 2923 | * |
| 2924 | * This function only works if it is called before the the item has been |
| 2925 | * committed. It will try to free the event from the ring buffer |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2926 | * if another event has not been added behind it. |
| 2927 | * |
| 2928 | * If another event has been added behind it, it will set the event |
| 2929 | * up as discarded, and perform the commit. |
| 2930 | * |
| 2931 | * If this function is called, do not call ring_buffer_unlock_commit on |
| 2932 | * the event. |
| 2933 | */ |
| 2934 | void ring_buffer_discard_commit(struct ring_buffer *buffer, |
| 2935 | struct ring_buffer_event *event) |
| 2936 | { |
| 2937 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2938 | int cpu; |
| 2939 | |
| 2940 | /* The event is discarded regardless */ |
Frederic Weisbecker | f3b9aae | 2009-04-19 23:39:33 +0200 | [diff] [blame] | 2941 | rb_event_discard(event); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2942 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2943 | cpu = smp_processor_id(); |
| 2944 | cpu_buffer = buffer->buffers[cpu]; |
| 2945 | |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2946 | /* |
| 2947 | * This must only be called if the event has not been |
| 2948 | * committed yet. Thus we can assume that preemption |
| 2949 | * is still disabled. |
| 2950 | */ |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2951 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2952 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2953 | rb_decrement_entry(cpu_buffer, event); |
Steven Rostedt | 0f2541d | 2009-08-05 12:02:48 -0400 | [diff] [blame] | 2954 | if (rb_try_to_discard(cpu_buffer, event)) |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2955 | goto out; |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2956 | |
| 2957 | /* |
| 2958 | * The commit is still visible by the reader, so we |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2959 | * must still update the timestamp. |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2960 | */ |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2961 | rb_update_write_stamp(cpu_buffer, event); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2962 | out: |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2963 | rb_end_commit(cpu_buffer); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2964 | |
Steven Rostedt (Red Hat) | 58a09ec | 2015-05-27 10:27:47 -0400 | [diff] [blame] | 2965 | trace_recursive_unlock(cpu_buffer); |
Frederic Weisbecker | f3b9aae | 2009-04-19 23:39:33 +0200 | [diff] [blame] | 2966 | |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2967 | preempt_enable_notrace(); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2968 | |
| 2969 | } |
| 2970 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); |
| 2971 | |
| 2972 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2973 | * ring_buffer_write - write data to the buffer without reserving |
| 2974 | * @buffer: The ring buffer to write to. |
| 2975 | * @length: The length of the data being written (excluding the event header) |
| 2976 | * @data: The data to write to the buffer. |
| 2977 | * |
| 2978 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as |
| 2979 | * one function. If you already have the data to write to the buffer, it |
| 2980 | * may be easier to simply call this function. |
| 2981 | * |
| 2982 | * Note, like ring_buffer_lock_reserve, the length is the length of the data |
| 2983 | * and not the length of the event which would hold the header. |
| 2984 | */ |
| 2985 | int ring_buffer_write(struct ring_buffer *buffer, |
David Sharp | 01e3e71 | 2012-06-07 16:46:24 -0700 | [diff] [blame] | 2986 | unsigned long length, |
| 2987 | void *data) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2988 | { |
| 2989 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2990 | struct ring_buffer_event *event; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2991 | void *body; |
| 2992 | int ret = -EBUSY; |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2993 | int cpu; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2994 | |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2995 | preempt_disable_notrace(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2996 | |
Lai Jiangshan | 52fbe9c | 2010-03-08 14:50:43 +0800 | [diff] [blame] | 2997 | if (atomic_read(&buffer->record_disabled)) |
| 2998 | goto out; |
| 2999 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3000 | cpu = raw_smp_processor_id(); |
| 3001 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3002 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3003 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3004 | |
| 3005 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3006 | |
| 3007 | if (atomic_read(&cpu_buffer->record_disabled)) |
| 3008 | goto out; |
| 3009 | |
Steven Rostedt | be957c4 | 2009-05-11 14:42:53 -0400 | [diff] [blame] | 3010 | if (length > BUF_MAX_DATA_SIZE) |
| 3011 | goto out; |
| 3012 | |
Steven Rostedt (Red Hat) | 985e871 | 2015-05-27 10:48:56 -0400 | [diff] [blame] | 3013 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
| 3014 | goto out; |
| 3015 | |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 3016 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3017 | if (!event) |
Steven Rostedt (Red Hat) | 985e871 | 2015-05-27 10:48:56 -0400 | [diff] [blame] | 3018 | goto out_unlock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3019 | |
| 3020 | body = rb_event_data(event); |
| 3021 | |
| 3022 | memcpy(body, data, length); |
| 3023 | |
| 3024 | rb_commit(cpu_buffer, event); |
| 3025 | |
Steven Rostedt (Red Hat) | 1569345 | 2013-02-28 19:59:17 -0500 | [diff] [blame] | 3026 | rb_wakeups(buffer, cpu_buffer); |
| 3027 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3028 | ret = 0; |
Steven Rostedt (Red Hat) | 985e871 | 2015-05-27 10:48:56 -0400 | [diff] [blame] | 3029 | |
| 3030 | out_unlock: |
| 3031 | trace_recursive_unlock(cpu_buffer); |
| 3032 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3033 | out: |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 3034 | preempt_enable_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3035 | |
| 3036 | return ret; |
| 3037 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3038 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3039 | |
Yaowei Bai | da58834 | 2015-09-29 22:43:33 +0800 | [diff] [blame] | 3040 | static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3041 | { |
| 3042 | struct buffer_page *reader = cpu_buffer->reader_page; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3043 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3044 | struct buffer_page *commit = cpu_buffer->commit_page; |
| 3045 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3046 | /* In case of error, head will be NULL */ |
| 3047 | if (unlikely(!head)) |
Yaowei Bai | da58834 | 2015-09-29 22:43:33 +0800 | [diff] [blame] | 3048 | return true; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3049 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3050 | return reader->read == rb_page_commit(reader) && |
| 3051 | (commit == reader || |
| 3052 | (commit == head && |
| 3053 | head->read == rb_page_commit(commit))); |
| 3054 | } |
| 3055 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3056 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3057 | * ring_buffer_record_disable - stop all writes into the buffer |
| 3058 | * @buffer: The ring buffer to stop writes to. |
| 3059 | * |
| 3060 | * This prevents all writes to the buffer. Any attempt to write |
| 3061 | * to the buffer after this will fail and return NULL. |
| 3062 | * |
| 3063 | * The caller should call synchronize_sched() after this. |
| 3064 | */ |
| 3065 | void ring_buffer_record_disable(struct ring_buffer *buffer) |
| 3066 | { |
| 3067 | atomic_inc(&buffer->record_disabled); |
| 3068 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3069 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3070 | |
| 3071 | /** |
| 3072 | * ring_buffer_record_enable - enable writes to the buffer |
| 3073 | * @buffer: The ring buffer to enable writes |
| 3074 | * |
| 3075 | * Note, multiple disables will need the same number of enables |
Adam Buchbinder | c41b20e | 2009-12-11 16:35:39 -0500 | [diff] [blame] | 3076 | * to truly enable the writing (much like preempt_disable). |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3077 | */ |
| 3078 | void ring_buffer_record_enable(struct ring_buffer *buffer) |
| 3079 | { |
| 3080 | atomic_dec(&buffer->record_disabled); |
| 3081 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3082 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3083 | |
| 3084 | /** |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 3085 | * ring_buffer_record_off - stop all writes into the buffer |
| 3086 | * @buffer: The ring buffer to stop writes to. |
| 3087 | * |
| 3088 | * This prevents all writes to the buffer. Any attempt to write |
| 3089 | * to the buffer after this will fail and return NULL. |
| 3090 | * |
| 3091 | * This is different than ring_buffer_record_disable() as |
Wang Tianhong | 87abb3b | 2012-08-02 14:02:00 +0800 | [diff] [blame] | 3092 | * it works like an on/off switch, where as the disable() version |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 3093 | * must be paired with a enable(). |
| 3094 | */ |
| 3095 | void ring_buffer_record_off(struct ring_buffer *buffer) |
| 3096 | { |
| 3097 | unsigned int rd; |
| 3098 | unsigned int new_rd; |
| 3099 | |
| 3100 | do { |
| 3101 | rd = atomic_read(&buffer->record_disabled); |
| 3102 | new_rd = rd | RB_BUFFER_OFF; |
| 3103 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); |
| 3104 | } |
| 3105 | EXPORT_SYMBOL_GPL(ring_buffer_record_off); |
| 3106 | |
| 3107 | /** |
| 3108 | * ring_buffer_record_on - restart writes into the buffer |
| 3109 | * @buffer: The ring buffer to start writes to. |
| 3110 | * |
| 3111 | * This enables all writes to the buffer that was disabled by |
| 3112 | * ring_buffer_record_off(). |
| 3113 | * |
| 3114 | * This is different than ring_buffer_record_enable() as |
Wang Tianhong | 87abb3b | 2012-08-02 14:02:00 +0800 | [diff] [blame] | 3115 | * it works like an on/off switch, where as the enable() version |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 3116 | * must be paired with a disable(). |
| 3117 | */ |
| 3118 | void ring_buffer_record_on(struct ring_buffer *buffer) |
| 3119 | { |
| 3120 | unsigned int rd; |
| 3121 | unsigned int new_rd; |
| 3122 | |
| 3123 | do { |
| 3124 | rd = atomic_read(&buffer->record_disabled); |
| 3125 | new_rd = rd & ~RB_BUFFER_OFF; |
| 3126 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); |
| 3127 | } |
| 3128 | EXPORT_SYMBOL_GPL(ring_buffer_record_on); |
| 3129 | |
| 3130 | /** |
| 3131 | * ring_buffer_record_is_on - return true if the ring buffer can write |
| 3132 | * @buffer: The ring buffer to see if write is enabled |
| 3133 | * |
| 3134 | * Returns true if the ring buffer is in a state that it accepts writes. |
| 3135 | */ |
| 3136 | int ring_buffer_record_is_on(struct ring_buffer *buffer) |
| 3137 | { |
| 3138 | return !atomic_read(&buffer->record_disabled); |
| 3139 | } |
| 3140 | |
| 3141 | /** |
Masami Hiramatsu | a26030a | 2018-07-14 01:28:15 +0900 | [diff] [blame] | 3142 | * ring_buffer_record_is_set_on - return true if the ring buffer is set writable |
| 3143 | * @buffer: The ring buffer to see if write is set enabled |
| 3144 | * |
| 3145 | * Returns true if the ring buffer is set writable by ring_buffer_record_on(). |
| 3146 | * Note that this does NOT mean it is in a writable state. |
| 3147 | * |
| 3148 | * It may return true when the ring buffer has been disabled by |
| 3149 | * ring_buffer_record_disable(), as that is a temporary disabling of |
| 3150 | * the ring buffer. |
| 3151 | */ |
| 3152 | int ring_buffer_record_is_set_on(struct ring_buffer *buffer) |
| 3153 | { |
| 3154 | return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF); |
| 3155 | } |
| 3156 | |
| 3157 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3158 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer |
| 3159 | * @buffer: The ring buffer to stop writes to. |
| 3160 | * @cpu: The CPU buffer to stop |
| 3161 | * |
| 3162 | * This prevents all writes to the buffer. Any attempt to write |
| 3163 | * to the buffer after this will fail and return NULL. |
| 3164 | * |
| 3165 | * The caller should call synchronize_sched() after this. |
| 3166 | */ |
| 3167 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) |
| 3168 | { |
| 3169 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3170 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3171 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3172 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3173 | |
| 3174 | cpu_buffer = buffer->buffers[cpu]; |
| 3175 | atomic_inc(&cpu_buffer->record_disabled); |
| 3176 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3177 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3178 | |
| 3179 | /** |
| 3180 | * ring_buffer_record_enable_cpu - enable writes to the buffer |
| 3181 | * @buffer: The ring buffer to enable writes |
| 3182 | * @cpu: The CPU to enable. |
| 3183 | * |
| 3184 | * Note, multiple disables will need the same number of enables |
Adam Buchbinder | c41b20e | 2009-12-11 16:35:39 -0500 | [diff] [blame] | 3185 | * to truly enable the writing (much like preempt_disable). |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3186 | */ |
| 3187 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) |
| 3188 | { |
| 3189 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3190 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3191 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3192 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3193 | |
| 3194 | cpu_buffer = buffer->buffers[cpu]; |
| 3195 | atomic_dec(&cpu_buffer->record_disabled); |
| 3196 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3197 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3198 | |
Steven Rostedt | f6195aa | 2010-09-01 12:23:12 -0400 | [diff] [blame] | 3199 | /* |
| 3200 | * The total entries in the ring buffer is the running counter |
| 3201 | * of entries entered into the ring buffer, minus the sum of |
| 3202 | * the entries read from the ring buffer and the number of |
| 3203 | * entries that were overwritten. |
| 3204 | */ |
| 3205 | static inline unsigned long |
| 3206 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) |
| 3207 | { |
| 3208 | return local_read(&cpu_buffer->entries) - |
| 3209 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); |
| 3210 | } |
| 3211 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3212 | /** |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3213 | * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer |
| 3214 | * @buffer: The ring buffer |
| 3215 | * @cpu: The per CPU buffer to read from. |
| 3216 | */ |
Yoshihiro YUNOMAE | 50ecf2c | 2012-10-11 16:27:54 -0700 | [diff] [blame] | 3217 | u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3218 | { |
| 3219 | unsigned long flags; |
| 3220 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3221 | struct buffer_page *bpage; |
Linus Torvalds | da830e5 | 2012-12-11 18:18:58 -0800 | [diff] [blame] | 3222 | u64 ret = 0; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3223 | |
| 3224 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3225 | return 0; |
| 3226 | |
| 3227 | cpu_buffer = buffer->buffers[cpu]; |
Linus Torvalds | 7115e3f | 2011-10-26 17:03:38 +0200 | [diff] [blame] | 3228 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3229 | /* |
| 3230 | * if the tail is on reader_page, oldest time stamp is on the reader |
| 3231 | * page |
| 3232 | */ |
| 3233 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) |
| 3234 | bpage = cpu_buffer->reader_page; |
| 3235 | else |
| 3236 | bpage = rb_set_head_page(cpu_buffer); |
Steven Rostedt | 54f7be5 | 2012-11-29 22:27:22 -0500 | [diff] [blame] | 3237 | if (bpage) |
| 3238 | ret = bpage->page->time_stamp; |
Linus Torvalds | 7115e3f | 2011-10-26 17:03:38 +0200 | [diff] [blame] | 3239 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3240 | |
| 3241 | return ret; |
| 3242 | } |
| 3243 | EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); |
| 3244 | |
| 3245 | /** |
| 3246 | * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer |
| 3247 | * @buffer: The ring buffer |
| 3248 | * @cpu: The per CPU buffer to read from. |
| 3249 | */ |
| 3250 | unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu) |
| 3251 | { |
| 3252 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3253 | unsigned long ret; |
| 3254 | |
| 3255 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3256 | return 0; |
| 3257 | |
| 3258 | cpu_buffer = buffer->buffers[cpu]; |
| 3259 | ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; |
| 3260 | |
| 3261 | return ret; |
| 3262 | } |
| 3263 | EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); |
| 3264 | |
| 3265 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3266 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer |
| 3267 | * @buffer: The ring buffer |
| 3268 | * @cpu: The per CPU buffer to get the entries from. |
| 3269 | */ |
| 3270 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) |
| 3271 | { |
| 3272 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3273 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3274 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3275 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3276 | |
| 3277 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3278 | |
Steven Rostedt | f6195aa | 2010-09-01 12:23:12 -0400 | [diff] [blame] | 3279 | return rb_num_of_entries(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3280 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3281 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3282 | |
| 3283 | /** |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3284 | * ring_buffer_overrun_cpu - get the number of overruns caused by the ring |
| 3285 | * buffer wrapping around (only if RB_FL_OVERWRITE is on). |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3286 | * @buffer: The ring buffer |
| 3287 | * @cpu: The per CPU buffer to get the number of overruns from |
| 3288 | */ |
| 3289 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) |
| 3290 | { |
| 3291 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3292 | unsigned long ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3293 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3294 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3295 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3296 | |
| 3297 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3298 | ret = local_read(&cpu_buffer->overrun); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3299 | |
| 3300 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3301 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3302 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3303 | |
| 3304 | /** |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3305 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by |
| 3306 | * commits failing due to the buffer wrapping around while there are uncommitted |
| 3307 | * events, such as during an interrupt storm. |
Steven Rostedt | f0d2c68 | 2009-04-29 13:43:37 -0400 | [diff] [blame] | 3308 | * @buffer: The ring buffer |
| 3309 | * @cpu: The per CPU buffer to get the number of overruns from |
| 3310 | */ |
| 3311 | unsigned long |
| 3312 | ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) |
| 3313 | { |
| 3314 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3315 | unsigned long ret; |
| 3316 | |
| 3317 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3318 | return 0; |
| 3319 | |
| 3320 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3321 | ret = local_read(&cpu_buffer->commit_overrun); |
Steven Rostedt | f0d2c68 | 2009-04-29 13:43:37 -0400 | [diff] [blame] | 3322 | |
| 3323 | return ret; |
| 3324 | } |
| 3325 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); |
| 3326 | |
| 3327 | /** |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3328 | * ring_buffer_dropped_events_cpu - get the number of dropped events caused by |
| 3329 | * the ring buffer filling up (only if RB_FL_OVERWRITE is off). |
| 3330 | * @buffer: The ring buffer |
| 3331 | * @cpu: The per CPU buffer to get the number of overruns from |
| 3332 | */ |
| 3333 | unsigned long |
| 3334 | ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu) |
| 3335 | { |
| 3336 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3337 | unsigned long ret; |
| 3338 | |
| 3339 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3340 | return 0; |
| 3341 | |
| 3342 | cpu_buffer = buffer->buffers[cpu]; |
| 3343 | ret = local_read(&cpu_buffer->dropped_events); |
| 3344 | |
| 3345 | return ret; |
| 3346 | } |
| 3347 | EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); |
| 3348 | |
| 3349 | /** |
Steven Rostedt (Red Hat) | ad96470 | 2013-01-29 17:45:49 -0500 | [diff] [blame] | 3350 | * ring_buffer_read_events_cpu - get the number of events successfully read |
| 3351 | * @buffer: The ring buffer |
| 3352 | * @cpu: The per CPU buffer to get the number of events read |
| 3353 | */ |
| 3354 | unsigned long |
| 3355 | ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu) |
| 3356 | { |
| 3357 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3358 | |
| 3359 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3360 | return 0; |
| 3361 | |
| 3362 | cpu_buffer = buffer->buffers[cpu]; |
| 3363 | return cpu_buffer->read; |
| 3364 | } |
| 3365 | EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu); |
| 3366 | |
| 3367 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3368 | * ring_buffer_entries - get the number of entries in a buffer |
| 3369 | * @buffer: The ring buffer |
| 3370 | * |
| 3371 | * Returns the total number of entries in the ring buffer |
| 3372 | * (all CPU entries) |
| 3373 | */ |
| 3374 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) |
| 3375 | { |
| 3376 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3377 | unsigned long entries = 0; |
| 3378 | int cpu; |
| 3379 | |
| 3380 | /* if you care about this being correct, lock the buffer */ |
| 3381 | for_each_buffer_cpu(buffer, cpu) { |
| 3382 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | f6195aa | 2010-09-01 12:23:12 -0400 | [diff] [blame] | 3383 | entries += rb_num_of_entries(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3384 | } |
| 3385 | |
| 3386 | return entries; |
| 3387 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3388 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3389 | |
| 3390 | /** |
Jiri Olsa | 67b394f | 2009-10-23 19:36:18 -0400 | [diff] [blame] | 3391 | * ring_buffer_overruns - get the number of overruns in buffer |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3392 | * @buffer: The ring buffer |
| 3393 | * |
| 3394 | * Returns the total number of overruns in the ring buffer |
| 3395 | * (all CPU entries) |
| 3396 | */ |
| 3397 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) |
| 3398 | { |
| 3399 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3400 | unsigned long overruns = 0; |
| 3401 | int cpu; |
| 3402 | |
| 3403 | /* if you care about this being correct, lock the buffer */ |
| 3404 | for_each_buffer_cpu(buffer, cpu) { |
| 3405 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3406 | overruns += local_read(&cpu_buffer->overrun); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3407 | } |
| 3408 | |
| 3409 | return overruns; |
| 3410 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3411 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3412 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3413 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3414 | { |
| 3415 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 3416 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3417 | /* Iterator usage is expected to have record disabled */ |
Steven Rostedt (Red Hat) | 651e22f | 2014-08-06 14:11:33 -0400 | [diff] [blame] | 3418 | iter->head_page = cpu_buffer->reader_page; |
| 3419 | iter->head = cpu_buffer->reader_page->read; |
| 3420 | |
| 3421 | iter->cache_reader_page = iter->head_page; |
Steven Rostedt (Red Hat) | 24607f1 | 2014-10-02 16:51:18 -0400 | [diff] [blame] | 3422 | iter->cache_read = cpu_buffer->read; |
Steven Rostedt (Red Hat) | 651e22f | 2014-08-06 14:11:33 -0400 | [diff] [blame] | 3423 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3424 | if (iter->head) |
| 3425 | iter->read_stamp = cpu_buffer->read_stamp; |
| 3426 | else |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 3427 | iter->read_stamp = iter->head_page->page->time_stamp; |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3428 | } |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3429 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3430 | /** |
| 3431 | * ring_buffer_iter_reset - reset an iterator |
| 3432 | * @iter: The iterator to reset |
| 3433 | * |
| 3434 | * Resets the iterator, so that it will start from the beginning |
| 3435 | * again. |
| 3436 | */ |
| 3437 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) |
| 3438 | { |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3439 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3440 | unsigned long flags; |
| 3441 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3442 | if (!iter) |
| 3443 | return; |
| 3444 | |
| 3445 | cpu_buffer = iter->cpu_buffer; |
| 3446 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3447 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3448 | rb_iter_reset(iter); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3449 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3450 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3451 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3452 | |
| 3453 | /** |
| 3454 | * ring_buffer_iter_empty - check if an iterator has no more to read |
| 3455 | * @iter: The iterator to check |
| 3456 | */ |
| 3457 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) |
| 3458 | { |
| 3459 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt (VMware) | d80e9071 | 2017-04-19 14:29:46 -0400 | [diff] [blame] | 3460 | struct buffer_page *reader; |
| 3461 | struct buffer_page *head_page; |
| 3462 | struct buffer_page *commit_page; |
| 3463 | unsigned commit; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3464 | |
| 3465 | cpu_buffer = iter->cpu_buffer; |
| 3466 | |
Steven Rostedt (VMware) | d80e9071 | 2017-04-19 14:29:46 -0400 | [diff] [blame] | 3467 | /* Remember, trace recording is off when iterator is in use */ |
| 3468 | reader = cpu_buffer->reader_page; |
| 3469 | head_page = cpu_buffer->head_page; |
| 3470 | commit_page = cpu_buffer->commit_page; |
| 3471 | commit = rb_page_commit(commit_page); |
| 3472 | |
| 3473 | return ((iter->head_page == commit_page && iter->head == commit) || |
| 3474 | (iter->head_page == reader && commit_page == head_page && |
| 3475 | head_page->read == commit && |
| 3476 | iter->head == rb_page_commit(cpu_buffer->reader_page))); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3477 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3478 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3479 | |
| 3480 | static void |
| 3481 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
| 3482 | struct ring_buffer_event *event) |
| 3483 | { |
| 3484 | u64 delta; |
| 3485 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3486 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3487 | case RINGBUF_TYPE_PADDING: |
| 3488 | return; |
| 3489 | |
| 3490 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3491 | delta = event->array[0]; |
| 3492 | delta <<= TS_SHIFT; |
| 3493 | delta += event->time_delta; |
| 3494 | cpu_buffer->read_stamp += delta; |
| 3495 | return; |
| 3496 | |
| 3497 | case RINGBUF_TYPE_TIME_STAMP: |
| 3498 | /* FIXME: not implemented */ |
| 3499 | return; |
| 3500 | |
| 3501 | case RINGBUF_TYPE_DATA: |
| 3502 | cpu_buffer->read_stamp += event->time_delta; |
| 3503 | return; |
| 3504 | |
| 3505 | default: |
| 3506 | BUG(); |
| 3507 | } |
| 3508 | return; |
| 3509 | } |
| 3510 | |
| 3511 | static void |
| 3512 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, |
| 3513 | struct ring_buffer_event *event) |
| 3514 | { |
| 3515 | u64 delta; |
| 3516 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3517 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3518 | case RINGBUF_TYPE_PADDING: |
| 3519 | return; |
| 3520 | |
| 3521 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3522 | delta = event->array[0]; |
| 3523 | delta <<= TS_SHIFT; |
| 3524 | delta += event->time_delta; |
| 3525 | iter->read_stamp += delta; |
| 3526 | return; |
| 3527 | |
| 3528 | case RINGBUF_TYPE_TIME_STAMP: |
| 3529 | /* FIXME: not implemented */ |
| 3530 | return; |
| 3531 | |
| 3532 | case RINGBUF_TYPE_DATA: |
| 3533 | iter->read_stamp += event->time_delta; |
| 3534 | return; |
| 3535 | |
| 3536 | default: |
| 3537 | BUG(); |
| 3538 | } |
| 3539 | return; |
| 3540 | } |
| 3541 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3542 | static struct buffer_page * |
| 3543 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3544 | { |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3545 | struct buffer_page *reader = NULL; |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3546 | unsigned long overwrite; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3547 | unsigned long flags; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3548 | int nr_loops = 0; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3549 | int ret; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3550 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 3551 | local_irq_save(flags); |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3552 | arch_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3553 | |
| 3554 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3555 | /* |
| 3556 | * This should normally only loop twice. But because the |
| 3557 | * start of the reader inserts an empty page, it causes |
| 3558 | * a case where we will loop three times. There should be no |
| 3559 | * reason to loop four times (that I know of). |
| 3560 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3561 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3562 | reader = NULL; |
| 3563 | goto out; |
| 3564 | } |
| 3565 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3566 | reader = cpu_buffer->reader_page; |
| 3567 | |
| 3568 | /* If there's more to read, return this page */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3569 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3570 | goto out; |
| 3571 | |
| 3572 | /* Never should we have an index greater than the size */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3573 | if (RB_WARN_ON(cpu_buffer, |
| 3574 | cpu_buffer->reader_page->read > rb_page_size(reader))) |
| 3575 | goto out; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3576 | |
| 3577 | /* check if we caught up to the tail */ |
| 3578 | reader = NULL; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3579 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3580 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3581 | |
Steven Rostedt | a5fb833 | 2012-06-28 13:35:04 -0400 | [diff] [blame] | 3582 | /* Don't bother swapping if the ring buffer is empty */ |
| 3583 | if (rb_num_of_entries(cpu_buffer) == 0) |
| 3584 | goto out; |
| 3585 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3586 | /* |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3587 | * Reset the reader page to size zero. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3588 | */ |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3589 | local_set(&cpu_buffer->reader_page->write, 0); |
| 3590 | local_set(&cpu_buffer->reader_page->entries, 0); |
| 3591 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 3592 | cpu_buffer->reader_page->real_end = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3593 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3594 | spin: |
| 3595 | /* |
| 3596 | * Splice the empty reader page into the list around the head. |
| 3597 | */ |
| 3598 | reader = rb_set_head_page(cpu_buffer); |
Steven Rostedt | 54f7be5 | 2012-11-29 22:27:22 -0500 | [diff] [blame] | 3599 | if (!reader) |
| 3600 | goto out; |
Steven Rostedt | 0e1ff5d | 2010-01-06 20:40:44 -0500 | [diff] [blame] | 3601 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3602 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3603 | |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 3604 | /* |
| 3605 | * cpu_buffer->pages just needs to point to the buffer, it |
| 3606 | * has no specific buffer page to point to. Lets move it out |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 3607 | * of our way so we don't accidentally swap it. |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 3608 | */ |
| 3609 | cpu_buffer->pages = reader->list.prev; |
| 3610 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3611 | /* The reader page will be pointing to the new head */ |
| 3612 | rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3613 | |
| 3614 | /* |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3615 | * We want to make sure we read the overruns after we set up our |
| 3616 | * pointers to the next object. The writer side does a |
| 3617 | * cmpxchg to cross pages which acts as the mb on the writer |
| 3618 | * side. Note, the reader will constantly fail the swap |
| 3619 | * while the writer is updating the pointers, so this |
| 3620 | * guarantees that the overwrite recorded here is the one we |
| 3621 | * want to compare with the last_overrun. |
| 3622 | */ |
| 3623 | smp_mb(); |
| 3624 | overwrite = local_read(&(cpu_buffer->overrun)); |
| 3625 | |
| 3626 | /* |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3627 | * Here's the tricky part. |
| 3628 | * |
| 3629 | * We need to move the pointer past the header page. |
| 3630 | * But we can only do that if a writer is not currently |
| 3631 | * moving it. The page before the header page has the |
| 3632 | * flag bit '1' set if it is pointing to the page we want. |
| 3633 | * but if the writer is in the process of moving it |
| 3634 | * than it will be '2' or already moved '0'. |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3635 | */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3636 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3637 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); |
| 3638 | |
| 3639 | /* |
| 3640 | * If we did not convert it, then we must try again. |
| 3641 | */ |
| 3642 | if (!ret) |
| 3643 | goto spin; |
| 3644 | |
| 3645 | /* |
| 3646 | * Yeah! We succeeded in replacing the page. |
| 3647 | * |
| 3648 | * Now make the new head point back to the reader page. |
| 3649 | */ |
David Sharp | 5ded3dc6 | 2010-01-06 17:12:07 -0800 | [diff] [blame] | 3650 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3651 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3652 | |
| 3653 | /* Finally update the reader page to the new head */ |
| 3654 | cpu_buffer->reader_page = reader; |
Steven Rostedt (Red Hat) | b81f472 | 2015-11-23 10:35:36 -0500 | [diff] [blame] | 3655 | cpu_buffer->reader_page->read = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3656 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3657 | if (overwrite != cpu_buffer->last_overrun) { |
| 3658 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; |
| 3659 | cpu_buffer->last_overrun = overwrite; |
| 3660 | } |
| 3661 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3662 | goto again; |
| 3663 | |
| 3664 | out: |
Steven Rostedt (Red Hat) | b81f472 | 2015-11-23 10:35:36 -0500 | [diff] [blame] | 3665 | /* Update the read_stamp on the first event */ |
| 3666 | if (reader && reader->read == 0) |
| 3667 | cpu_buffer->read_stamp = reader->page->time_stamp; |
| 3668 | |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3669 | arch_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 3670 | local_irq_restore(flags); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3671 | |
| 3672 | return reader; |
| 3673 | } |
| 3674 | |
| 3675 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) |
| 3676 | { |
| 3677 | struct ring_buffer_event *event; |
| 3678 | struct buffer_page *reader; |
| 3679 | unsigned length; |
| 3680 | |
| 3681 | reader = rb_get_reader_page(cpu_buffer); |
| 3682 | |
| 3683 | /* This function should not be called when buffer is empty */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3684 | if (RB_WARN_ON(cpu_buffer, !reader)) |
| 3685 | return; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3686 | |
| 3687 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3688 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 3689 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
Steven Rostedt | e4906ef | 2009-04-30 20:49:44 -0400 | [diff] [blame] | 3690 | cpu_buffer->read++; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3691 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3692 | rb_update_read_stamp(cpu_buffer, event); |
| 3693 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3694 | length = rb_event_length(event); |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 3695 | cpu_buffer->reader_page->read += length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3696 | } |
| 3697 | |
| 3698 | static void rb_advance_iter(struct ring_buffer_iter *iter) |
| 3699 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3700 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3701 | struct ring_buffer_event *event; |
| 3702 | unsigned length; |
| 3703 | |
| 3704 | cpu_buffer = iter->cpu_buffer; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3705 | |
| 3706 | /* |
| 3707 | * Check if we are at the end of the buffer. |
| 3708 | */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3709 | if (iter->head >= rb_page_size(iter->head_page)) { |
Steven Rostedt | ea05b57 | 2009-06-03 09:30:10 -0400 | [diff] [blame] | 3710 | /* discarded commits can make the page empty */ |
| 3711 | if (iter->head_page == cpu_buffer->commit_page) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3712 | return; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3713 | rb_inc_iter(iter); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3714 | return; |
| 3715 | } |
| 3716 | |
| 3717 | event = rb_iter_head_event(iter); |
| 3718 | |
| 3719 | length = rb_event_length(event); |
| 3720 | |
| 3721 | /* |
| 3722 | * This should not be called to advance the header if we are |
| 3723 | * at the tail of the buffer. |
| 3724 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3725 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 3726 | (iter->head_page == cpu_buffer->commit_page) && |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3727 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
| 3728 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3729 | |
| 3730 | rb_update_iter_read_stamp(iter, event); |
| 3731 | |
| 3732 | iter->head += length; |
| 3733 | |
| 3734 | /* check for end of page padding */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3735 | if ((iter->head >= rb_page_size(iter->head_page)) && |
| 3736 | (iter->head_page != cpu_buffer->commit_page)) |
Steven Rostedt | 771e038 | 2012-11-30 10:41:57 -0500 | [diff] [blame] | 3737 | rb_inc_iter(iter); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3738 | } |
| 3739 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3740 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
| 3741 | { |
| 3742 | return cpu_buffer->lost_events; |
| 3743 | } |
| 3744 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3745 | static struct ring_buffer_event * |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3746 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
| 3747 | unsigned long *lost_events) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3748 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3749 | struct ring_buffer_event *event; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3750 | struct buffer_page *reader; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3751 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3752 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3753 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3754 | /* |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 3755 | * We repeat when a time extend is encountered. |
| 3756 | * Since the time extend is always attached to a data event, |
| 3757 | * we should never loop more than once. |
| 3758 | * (We never hit the following condition more than twice). |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3759 | */ |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 3760 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3761 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3762 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3763 | reader = rb_get_reader_page(cpu_buffer); |
| 3764 | if (!reader) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3765 | return NULL; |
| 3766 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3767 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3768 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3769 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3770 | case RINGBUF_TYPE_PADDING: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3771 | if (rb_null_event(event)) |
| 3772 | RB_WARN_ON(cpu_buffer, 1); |
| 3773 | /* |
| 3774 | * Because the writer could be discarding every |
| 3775 | * event it creates (which would probably be bad) |
| 3776 | * if we were to go back to "again" then we may never |
| 3777 | * catch up, and will trigger the warn on, or lock |
| 3778 | * the box. Return the padding, and we will release |
| 3779 | * the current locks, and try again. |
| 3780 | */ |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3781 | return event; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3782 | |
| 3783 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3784 | /* Internal data, OK to advance */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3785 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3786 | goto again; |
| 3787 | |
| 3788 | case RINGBUF_TYPE_TIME_STAMP: |
| 3789 | /* FIXME: not implemented */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3790 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3791 | goto again; |
| 3792 | |
| 3793 | case RINGBUF_TYPE_DATA: |
| 3794 | if (ts) { |
| 3795 | *ts = cpu_buffer->read_stamp + event->time_delta; |
Robert Richter | d8eeb2d | 2009-07-31 14:58:04 +0200 | [diff] [blame] | 3796 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 3797 | cpu_buffer->cpu, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3798 | } |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3799 | if (lost_events) |
| 3800 | *lost_events = rb_lost_events(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3801 | return event; |
| 3802 | |
| 3803 | default: |
| 3804 | BUG(); |
| 3805 | } |
| 3806 | |
| 3807 | return NULL; |
| 3808 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3809 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3810 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3811 | static struct ring_buffer_event * |
| 3812 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3813 | { |
| 3814 | struct ring_buffer *buffer; |
| 3815 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3816 | struct ring_buffer_event *event; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3817 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3818 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3819 | cpu_buffer = iter->cpu_buffer; |
| 3820 | buffer = cpu_buffer->buffer; |
| 3821 | |
Steven Rostedt | 492a74f | 2010-01-25 15:17:47 -0500 | [diff] [blame] | 3822 | /* |
| 3823 | * Check if someone performed a consuming read to |
| 3824 | * the buffer. A consuming read invalidates the iterator |
| 3825 | * and we need to reset the iterator in this case. |
| 3826 | */ |
| 3827 | if (unlikely(iter->cache_read != cpu_buffer->read || |
| 3828 | iter->cache_reader_page != cpu_buffer->reader_page)) |
| 3829 | rb_iter_reset(iter); |
| 3830 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3831 | again: |
Steven Rostedt | 3c05d74 | 2010-01-26 16:14:08 -0500 | [diff] [blame] | 3832 | if (ring_buffer_iter_empty(iter)) |
| 3833 | return NULL; |
| 3834 | |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3835 | /* |
Steven Rostedt (Red Hat) | 021de3d | 2014-08-06 15:36:31 -0400 | [diff] [blame] | 3836 | * We repeat when a time extend is encountered or we hit |
| 3837 | * the end of the page. Since the time extend is always attached |
| 3838 | * to a data event, we should never loop more than three times. |
| 3839 | * Once for going to next page, once on time extend, and |
| 3840 | * finally once to get the event. |
| 3841 | * (We never hit the following condition more than thrice). |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3842 | */ |
Steven Rostedt (Red Hat) | 021de3d | 2014-08-06 15:36:31 -0400 | [diff] [blame] | 3843 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3844 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3845 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3846 | if (rb_per_cpu_empty(cpu_buffer)) |
| 3847 | return NULL; |
| 3848 | |
Steven Rostedt (Red Hat) | 10e83fd | 2014-07-23 19:45:12 -0400 | [diff] [blame] | 3849 | if (iter->head >= rb_page_size(iter->head_page)) { |
Steven Rostedt | 3c05d74 | 2010-01-26 16:14:08 -0500 | [diff] [blame] | 3850 | rb_inc_iter(iter); |
| 3851 | goto again; |
| 3852 | } |
| 3853 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3854 | event = rb_iter_head_event(iter); |
| 3855 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3856 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3857 | case RINGBUF_TYPE_PADDING: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3858 | if (rb_null_event(event)) { |
| 3859 | rb_inc_iter(iter); |
| 3860 | goto again; |
| 3861 | } |
| 3862 | rb_advance_iter(iter); |
| 3863 | return event; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3864 | |
| 3865 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3866 | /* Internal data, OK to advance */ |
| 3867 | rb_advance_iter(iter); |
| 3868 | goto again; |
| 3869 | |
| 3870 | case RINGBUF_TYPE_TIME_STAMP: |
| 3871 | /* FIXME: not implemented */ |
| 3872 | rb_advance_iter(iter); |
| 3873 | goto again; |
| 3874 | |
| 3875 | case RINGBUF_TYPE_DATA: |
| 3876 | if (ts) { |
| 3877 | *ts = iter->read_stamp + event->time_delta; |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 3878 | ring_buffer_normalize_time_stamp(buffer, |
| 3879 | cpu_buffer->cpu, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3880 | } |
| 3881 | return event; |
| 3882 | |
| 3883 | default: |
| 3884 | BUG(); |
| 3885 | } |
| 3886 | |
| 3887 | return NULL; |
| 3888 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3889 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3890 | |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3891 | static inline bool rb_reader_lock(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3892 | { |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3893 | if (likely(!in_nmi())) { |
| 3894 | raw_spin_lock(&cpu_buffer->reader_lock); |
| 3895 | return true; |
| 3896 | } |
| 3897 | |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3898 | /* |
| 3899 | * If an NMI die dumps out the content of the ring buffer |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3900 | * trylock must be used to prevent a deadlock if the NMI |
| 3901 | * preempted a task that holds the ring buffer locks. If |
| 3902 | * we get the lock then all is fine, if not, then continue |
| 3903 | * to do the read, but this can corrupt the ring buffer, |
| 3904 | * so it must be permanently disabled from future writes. |
| 3905 | * Reading from NMI is a oneshot deal. |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3906 | */ |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3907 | if (raw_spin_trylock(&cpu_buffer->reader_lock)) |
| 3908 | return true; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3909 | |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3910 | /* Continue without locking, but disable the ring buffer */ |
| 3911 | atomic_inc(&cpu_buffer->record_disabled); |
| 3912 | return false; |
| 3913 | } |
| 3914 | |
| 3915 | static inline void |
| 3916 | rb_reader_unlock(struct ring_buffer_per_cpu *cpu_buffer, bool locked) |
| 3917 | { |
| 3918 | if (likely(locked)) |
| 3919 | raw_spin_unlock(&cpu_buffer->reader_lock); |
| 3920 | return; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3921 | } |
| 3922 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3923 | /** |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3924 | * ring_buffer_peek - peek at the next event to be read |
| 3925 | * @buffer: The ring buffer to read |
| 3926 | * @cpu: The cpu to peak at |
| 3927 | * @ts: The timestamp counter of this event. |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3928 | * @lost_events: a variable to store if events were lost (may be NULL) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3929 | * |
| 3930 | * This will return the event that will be read next, but does |
| 3931 | * not consume the data. |
| 3932 | */ |
| 3933 | struct ring_buffer_event * |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3934 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, |
| 3935 | unsigned long *lost_events) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3936 | { |
| 3937 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3938 | struct ring_buffer_event *event; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3939 | unsigned long flags; |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3940 | bool dolock; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3941 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3942 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3943 | return NULL; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3944 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3945 | again: |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3946 | local_irq_save(flags); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3947 | dolock = rb_reader_lock(cpu_buffer); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3948 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
Robert Richter | 469535a | 2009-07-30 19:19:18 +0200 | [diff] [blame] | 3949 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
| 3950 | rb_advance_reader(cpu_buffer); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 3951 | rb_reader_unlock(cpu_buffer, dolock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3952 | local_irq_restore(flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3953 | |
Steven Rostedt | 1b959e1 | 2009-09-03 10:12:13 -0400 | [diff] [blame] | 3954 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3955 | goto again; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3956 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3957 | return event; |
| 3958 | } |
| 3959 | |
| 3960 | /** |
| 3961 | * ring_buffer_iter_peek - peek at the next event to be read |
| 3962 | * @iter: The ring buffer iterator |
| 3963 | * @ts: The timestamp counter of this event. |
| 3964 | * |
| 3965 | * This will return the event that will be read next, but does |
| 3966 | * not increment the iterator. |
| 3967 | */ |
| 3968 | struct ring_buffer_event * |
| 3969 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) |
| 3970 | { |
| 3971 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 3972 | struct ring_buffer_event *event; |
| 3973 | unsigned long flags; |
| 3974 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3975 | again: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3976 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3977 | event = rb_iter_peek(iter, ts); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3978 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3979 | |
Steven Rostedt | 1b959e1 | 2009-09-03 10:12:13 -0400 | [diff] [blame] | 3980 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3981 | goto again; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3982 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3983 | return event; |
| 3984 | } |
| 3985 | |
| 3986 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3987 | * ring_buffer_consume - return an event and consume it |
| 3988 | * @buffer: The ring buffer to get the next event from |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3989 | * @cpu: the cpu to read the buffer from |
| 3990 | * @ts: a variable to store the timestamp (may be NULL) |
| 3991 | * @lost_events: a variable to store if events were lost (may be NULL) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3992 | * |
| 3993 | * Returns the next event in the ring buffer, and that event is consumed. |
| 3994 | * Meaning, that sequential reads will keep returning a different event, |
| 3995 | * and eventually empty the ring buffer if the producer is slower. |
| 3996 | */ |
| 3997 | struct ring_buffer_event * |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3998 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, |
| 3999 | unsigned long *lost_events) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4000 | { |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4001 | struct ring_buffer_per_cpu *cpu_buffer; |
| 4002 | struct ring_buffer_event *event = NULL; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4003 | unsigned long flags; |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4004 | bool dolock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4005 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 4006 | again: |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4007 | /* might be called in atomic */ |
| 4008 | preempt_disable(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4009 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4010 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 4011 | goto out; |
| 4012 | |
| 4013 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4014 | local_irq_save(flags); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4015 | dolock = rb_reader_lock(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4016 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4017 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
| 4018 | if (event) { |
| 4019 | cpu_buffer->lost_events = 0; |
Robert Richter | 469535a | 2009-07-30 19:19:18 +0200 | [diff] [blame] | 4020 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4021 | } |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4022 | |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4023 | rb_reader_unlock(cpu_buffer, dolock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4024 | local_irq_restore(flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4025 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4026 | out: |
| 4027 | preempt_enable(); |
| 4028 | |
Steven Rostedt | 1b959e1 | 2009-09-03 10:12:13 -0400 | [diff] [blame] | 4029 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 4030 | goto again; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 4031 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4032 | return event; |
| 4033 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4034 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4035 | |
| 4036 | /** |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4037 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4038 | * @buffer: The ring buffer to read from |
| 4039 | * @cpu: The cpu buffer to iterate over |
Douglas Anderson | 3085d41 | 2019-03-08 11:32:04 -0800 | [diff] [blame] | 4040 | * @flags: gfp flags to use for memory allocation |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4041 | * |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4042 | * This performs the initial preparations necessary to iterate |
| 4043 | * through the buffer. Memory is allocated, buffer recording |
| 4044 | * is disabled, and the iterator pointer is returned to the caller. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4045 | * |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4046 | * Disabling buffer recordng prevents the reading from being |
| 4047 | * corrupted. This is not a consuming read, so a producer is not |
| 4048 | * expected. |
| 4049 | * |
| 4050 | * After a sequence of ring_buffer_read_prepare calls, the user is |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 4051 | * expected to make at least one call to ring_buffer_read_prepare_sync. |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4052 | * Afterwards, ring_buffer_read_start is invoked to get things going |
| 4053 | * for real. |
| 4054 | * |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 4055 | * This overall must be paired with ring_buffer_read_finish. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4056 | */ |
| 4057 | struct ring_buffer_iter * |
Douglas Anderson | 3085d41 | 2019-03-08 11:32:04 -0800 | [diff] [blame] | 4058 | ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4059 | { |
| 4060 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4061 | struct ring_buffer_iter *iter; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4062 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 4063 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4064 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4065 | |
Douglas Anderson | 3085d41 | 2019-03-08 11:32:04 -0800 | [diff] [blame] | 4066 | iter = kmalloc(sizeof(*iter), flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4067 | if (!iter) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4068 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4069 | |
| 4070 | cpu_buffer = buffer->buffers[cpu]; |
| 4071 | |
| 4072 | iter->cpu_buffer = cpu_buffer; |
| 4073 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 4074 | atomic_inc(&buffer->resize_disabled); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4075 | atomic_inc(&cpu_buffer->record_disabled); |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4076 | |
| 4077 | return iter; |
| 4078 | } |
| 4079 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); |
| 4080 | |
| 4081 | /** |
| 4082 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls |
| 4083 | * |
| 4084 | * All previously invoked ring_buffer_read_prepare calls to prepare |
| 4085 | * iterators will be synchronized. Afterwards, read_buffer_read_start |
| 4086 | * calls on those iterators are allowed. |
| 4087 | */ |
| 4088 | void |
| 4089 | ring_buffer_read_prepare_sync(void) |
| 4090 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4091 | synchronize_sched(); |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4092 | } |
| 4093 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); |
| 4094 | |
| 4095 | /** |
| 4096 | * ring_buffer_read_start - start a non consuming read of the buffer |
| 4097 | * @iter: The iterator returned by ring_buffer_read_prepare |
| 4098 | * |
| 4099 | * This finalizes the startup of an iteration through the buffer. |
| 4100 | * The iterator comes from a call to ring_buffer_read_prepare and |
| 4101 | * an intervening ring_buffer_read_prepare_sync must have been |
| 4102 | * performed. |
| 4103 | * |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 4104 | * Must be paired with ring_buffer_read_finish. |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 4105 | */ |
| 4106 | void |
| 4107 | ring_buffer_read_start(struct ring_buffer_iter *iter) |
| 4108 | { |
| 4109 | struct ring_buffer_per_cpu *cpu_buffer; |
| 4110 | unsigned long flags; |
| 4111 | |
| 4112 | if (!iter) |
| 4113 | return; |
| 4114 | |
| 4115 | cpu_buffer = iter->cpu_buffer; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4116 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4117 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 4118 | arch_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 4119 | rb_iter_reset(iter); |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 4120 | arch_spin_unlock(&cpu_buffer->lock); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4121 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4122 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4123 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4124 | |
| 4125 | /** |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 4126 | * ring_buffer_read_finish - finish reading the iterator of the buffer |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4127 | * @iter: The iterator retrieved by ring_buffer_start |
| 4128 | * |
| 4129 | * This re-enables the recording to the buffer, and frees the |
| 4130 | * iterator. |
| 4131 | */ |
| 4132 | void |
| 4133 | ring_buffer_read_finish(struct ring_buffer_iter *iter) |
| 4134 | { |
| 4135 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
Steven Rostedt | 9366c1b | 2012-11-29 22:31:16 -0500 | [diff] [blame] | 4136 | unsigned long flags; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4137 | |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 4138 | /* |
| 4139 | * Ring buffer is disabled from recording, here's a good place |
Steven Rostedt | 9366c1b | 2012-11-29 22:31:16 -0500 | [diff] [blame] | 4140 | * to check the integrity of the ring buffer. |
| 4141 | * Must prevent readers from trying to read, as the check |
| 4142 | * clears the HEAD page and readers require it. |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 4143 | */ |
Steven Rostedt | 9366c1b | 2012-11-29 22:31:16 -0500 | [diff] [blame] | 4144 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 4145 | rb_check_pages(cpu_buffer); |
Steven Rostedt | 9366c1b | 2012-11-29 22:31:16 -0500 | [diff] [blame] | 4146 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 4147 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4148 | atomic_dec(&cpu_buffer->record_disabled); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 4149 | atomic_dec(&cpu_buffer->buffer->resize_disabled); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4150 | kfree(iter); |
| 4151 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4152 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4153 | |
| 4154 | /** |
| 4155 | * ring_buffer_read - read the next item in the ring buffer by the iterator |
| 4156 | * @iter: The ring buffer iterator |
| 4157 | * @ts: The time stamp of the event read. |
| 4158 | * |
| 4159 | * This reads the next event in the ring buffer and increments the iterator. |
| 4160 | */ |
| 4161 | struct ring_buffer_event * |
| 4162 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) |
| 4163 | { |
| 4164 | struct ring_buffer_event *event; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4165 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 4166 | unsigned long flags; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4167 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4168 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7e9391c | 2009-09-03 10:02:09 -0400 | [diff] [blame] | 4169 | again: |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4170 | event = rb_iter_peek(iter, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4171 | if (!event) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4172 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4173 | |
Steven Rostedt | 7e9391c | 2009-09-03 10:02:09 -0400 | [diff] [blame] | 4174 | if (event->type_len == RINGBUF_TYPE_PADDING) |
| 4175 | goto again; |
| 4176 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4177 | rb_advance_iter(iter); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4178 | out: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4179 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4180 | |
| 4181 | return event; |
| 4182 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4183 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4184 | |
| 4185 | /** |
| 4186 | * ring_buffer_size - return the size of the ring buffer (in bytes) |
| 4187 | * @buffer: The ring buffer. |
| 4188 | */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4189 | unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4190 | { |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4191 | /* |
| 4192 | * Earlier, this method returned |
| 4193 | * BUF_PAGE_SIZE * buffer->nr_pages |
| 4194 | * Since the nr_pages field is now removed, we have converted this to |
| 4195 | * return the per cpu buffer value. |
| 4196 | */ |
| 4197 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 4198 | return 0; |
| 4199 | |
| 4200 | return BUF_PAGE_SIZE * buffer->buffers[cpu]->nr_pages; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4201 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4202 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4203 | |
| 4204 | static void |
| 4205 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) |
| 4206 | { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4207 | rb_head_page_deactivate(cpu_buffer); |
| 4208 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4209 | cpu_buffer->head_page |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 4210 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 4211 | local_set(&cpu_buffer->head_page->write, 0); |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 4212 | local_set(&cpu_buffer->head_page->entries, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 4213 | local_set(&cpu_buffer->head_page->page->commit, 0); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4214 | |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 4215 | cpu_buffer->head_page->read = 0; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 4216 | |
| 4217 | cpu_buffer->tail_page = cpu_buffer->head_page; |
| 4218 | cpu_buffer->commit_page = cpu_buffer->head_page; |
| 4219 | |
| 4220 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 4221 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 4222 | local_set(&cpu_buffer->reader_page->write, 0); |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 4223 | local_set(&cpu_buffer->reader_page->entries, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 4224 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 4225 | cpu_buffer->reader_page->read = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 4226 | |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 4227 | local_set(&cpu_buffer->entries_bytes, 0); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4228 | local_set(&cpu_buffer->overrun, 0); |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 4229 | local_set(&cpu_buffer->commit_overrun, 0); |
| 4230 | local_set(&cpu_buffer->dropped_events, 0); |
Steven Rostedt | e4906ef | 2009-04-30 20:49:44 -0400 | [diff] [blame] | 4231 | local_set(&cpu_buffer->entries, 0); |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 4232 | local_set(&cpu_buffer->committing, 0); |
| 4233 | local_set(&cpu_buffer->commits, 0); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4234 | cpu_buffer->read = 0; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 4235 | cpu_buffer->read_bytes = 0; |
Steven Rostedt | 69507c0 | 2009-01-21 18:45:57 -0500 | [diff] [blame] | 4236 | |
| 4237 | cpu_buffer->write_stamp = 0; |
| 4238 | cpu_buffer->read_stamp = 0; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4239 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4240 | cpu_buffer->lost_events = 0; |
| 4241 | cpu_buffer->last_overrun = 0; |
| 4242 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4243 | rb_head_page_activate(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4244 | } |
| 4245 | |
| 4246 | /** |
| 4247 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer |
| 4248 | * @buffer: The ring buffer to reset a per cpu buffer of |
| 4249 | * @cpu: The CPU buffer to be reset |
| 4250 | */ |
| 4251 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) |
| 4252 | { |
| 4253 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
| 4254 | unsigned long flags; |
| 4255 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 4256 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4257 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4258 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 4259 | atomic_inc(&buffer->resize_disabled); |
Steven Rostedt | 41ede23 | 2009-05-01 20:26:54 -0400 | [diff] [blame] | 4260 | atomic_inc(&cpu_buffer->record_disabled); |
| 4261 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 4262 | /* Make sure all commits have finished */ |
| 4263 | synchronize_sched(); |
| 4264 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4265 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4266 | |
Steven Rostedt | 41b6a95 | 2009-09-02 09:59:48 -0400 | [diff] [blame] | 4267 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) |
| 4268 | goto out; |
| 4269 | |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 4270 | arch_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4271 | |
| 4272 | rb_reset_cpu(cpu_buffer); |
| 4273 | |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 4274 | arch_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 4275 | |
Steven Rostedt | 41b6a95 | 2009-09-02 09:59:48 -0400 | [diff] [blame] | 4276 | out: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4277 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 41ede23 | 2009-05-01 20:26:54 -0400 | [diff] [blame] | 4278 | |
| 4279 | atomic_dec(&cpu_buffer->record_disabled); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 4280 | atomic_dec(&buffer->resize_disabled); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4281 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4282 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4283 | |
| 4284 | /** |
| 4285 | * ring_buffer_reset - reset a ring buffer |
| 4286 | * @buffer: The ring buffer to reset all cpu buffers |
| 4287 | */ |
| 4288 | void ring_buffer_reset(struct ring_buffer *buffer) |
| 4289 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4290 | int cpu; |
| 4291 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4292 | for_each_buffer_cpu(buffer, cpu) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 4293 | ring_buffer_reset_cpu(buffer, cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4294 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4295 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4296 | |
| 4297 | /** |
| 4298 | * rind_buffer_empty - is the ring buffer empty? |
| 4299 | * @buffer: The ring buffer to test |
| 4300 | */ |
Yaowei Bai | 3d4e204 | 2015-09-29 22:43:32 +0800 | [diff] [blame] | 4301 | bool ring_buffer_empty(struct ring_buffer *buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4302 | { |
| 4303 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 4304 | unsigned long flags; |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4305 | bool dolock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4306 | int cpu; |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 4307 | int ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4308 | |
| 4309 | /* yes this is racy, but if you don't like the race, lock the buffer */ |
| 4310 | for_each_buffer_cpu(buffer, cpu) { |
| 4311 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4312 | local_irq_save(flags); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4313 | dolock = rb_reader_lock(cpu_buffer); |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 4314 | ret = rb_per_cpu_empty(cpu_buffer); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4315 | rb_reader_unlock(cpu_buffer, dolock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4316 | local_irq_restore(flags); |
| 4317 | |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 4318 | if (!ret) |
Yaowei Bai | 3d4e204 | 2015-09-29 22:43:32 +0800 | [diff] [blame] | 4319 | return false; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4320 | } |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4321 | |
Yaowei Bai | 3d4e204 | 2015-09-29 22:43:32 +0800 | [diff] [blame] | 4322 | return true; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4323 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4324 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4325 | |
| 4326 | /** |
| 4327 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? |
| 4328 | * @buffer: The ring buffer |
| 4329 | * @cpu: The CPU buffer to test |
| 4330 | */ |
Yaowei Bai | 3d4e204 | 2015-09-29 22:43:32 +0800 | [diff] [blame] | 4331 | bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4332 | { |
| 4333 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 4334 | unsigned long flags; |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4335 | bool dolock; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4336 | int ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4337 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 4338 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Yaowei Bai | 3d4e204 | 2015-09-29 22:43:32 +0800 | [diff] [blame] | 4339 | return true; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4340 | |
| 4341 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4342 | local_irq_save(flags); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4343 | dolock = rb_reader_lock(cpu_buffer); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4344 | ret = rb_per_cpu_empty(cpu_buffer); |
Steven Rostedt (Red Hat) | 289a5a2 | 2015-05-28 13:14:51 -0400 | [diff] [blame] | 4345 | rb_reader_unlock(cpu_buffer, dolock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4346 | local_irq_restore(flags); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4347 | |
| 4348 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4349 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4350 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4351 | |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 4352 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4353 | /** |
| 4354 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers |
| 4355 | * @buffer_a: One buffer to swap with |
| 4356 | * @buffer_b: The other buffer to swap with |
| 4357 | * |
| 4358 | * This function is useful for tracers that want to take a "snapshot" |
| 4359 | * of a CPU buffer and has another back up buffer lying around. |
| 4360 | * it is expected that the tracer handles the cpu buffer not being |
| 4361 | * used at the moment. |
| 4362 | */ |
| 4363 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, |
| 4364 | struct ring_buffer *buffer_b, int cpu) |
| 4365 | { |
| 4366 | struct ring_buffer_per_cpu *cpu_buffer_a; |
| 4367 | struct ring_buffer_per_cpu *cpu_buffer_b; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4368 | int ret = -EINVAL; |
| 4369 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 4370 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
| 4371 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4372 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4373 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4374 | cpu_buffer_a = buffer_a->buffers[cpu]; |
| 4375 | cpu_buffer_b = buffer_b->buffers[cpu]; |
| 4376 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4377 | /* At least make sure the two buffers are somewhat the same */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4378 | if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4379 | goto out; |
| 4380 | |
| 4381 | ret = -EAGAIN; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4382 | |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4383 | if (atomic_read(&buffer_a->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4384 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4385 | |
| 4386 | if (atomic_read(&buffer_b->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4387 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4388 | |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4389 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4390 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4391 | |
| 4392 | if (atomic_read(&cpu_buffer_b->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4393 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4394 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4395 | /* |
| 4396 | * We can't do a synchronize_sched here because this |
| 4397 | * function can be called in atomic context. |
| 4398 | * Normally this will be called from the same CPU as cpu. |
| 4399 | * If not it's up to the caller to protect this. |
| 4400 | */ |
| 4401 | atomic_inc(&cpu_buffer_a->record_disabled); |
| 4402 | atomic_inc(&cpu_buffer_b->record_disabled); |
| 4403 | |
Steven Rostedt | 9827799 | 2009-09-02 10:56:15 -0400 | [diff] [blame] | 4404 | ret = -EBUSY; |
| 4405 | if (local_read(&cpu_buffer_a->committing)) |
| 4406 | goto out_dec; |
| 4407 | if (local_read(&cpu_buffer_b->committing)) |
| 4408 | goto out_dec; |
| 4409 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4410 | buffer_a->buffers[cpu] = cpu_buffer_b; |
| 4411 | buffer_b->buffers[cpu] = cpu_buffer_a; |
| 4412 | |
| 4413 | cpu_buffer_b->buffer = buffer_a; |
| 4414 | cpu_buffer_a->buffer = buffer_b; |
| 4415 | |
Steven Rostedt | 9827799 | 2009-09-02 10:56:15 -0400 | [diff] [blame] | 4416 | ret = 0; |
| 4417 | |
| 4418 | out_dec: |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4419 | atomic_dec(&cpu_buffer_a->record_disabled); |
| 4420 | atomic_dec(&cpu_buffer_b->record_disabled); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4421 | out: |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4422 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4423 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4424 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 4425 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4426 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4427 | /** |
| 4428 | * ring_buffer_alloc_read_page - allocate a page to read from buffer |
| 4429 | * @buffer: the buffer to allocate for. |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 4430 | * @cpu: the cpu buffer to allocate. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4431 | * |
| 4432 | * This function is used in conjunction with ring_buffer_read_page. |
| 4433 | * When reading a full page from the ring buffer, these functions |
| 4434 | * can be used to speed up the process. The calling function should |
| 4435 | * allocate a few pages first with this function. Then when it |
| 4436 | * needs to get pages from the ring buffer, it passes the result |
| 4437 | * of this function into ring_buffer_read_page, which will swap |
| 4438 | * the page that was allocated, with the read page of the buffer. |
| 4439 | * |
| 4440 | * Returns: |
| 4441 | * The page allocated, or NULL on error. |
| 4442 | */ |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4443 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4444 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4445 | struct buffer_data_page *bpage; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4446 | struct page *page; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4447 | |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 4448 | page = alloc_pages_node(cpu_to_node(cpu), |
| 4449 | GFP_KERNEL | __GFP_NORETRY, 0); |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4450 | if (!page) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4451 | return NULL; |
| 4452 | |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4453 | bpage = page_address(page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4454 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4455 | rb_init_page(bpage); |
| 4456 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4457 | return bpage; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4458 | } |
Steven Rostedt | d6ce96d | 2009-05-05 01:15:24 -0400 | [diff] [blame] | 4459 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4460 | |
| 4461 | /** |
| 4462 | * ring_buffer_free_read_page - free an allocated read page |
| 4463 | * @buffer: the buffer the page was allocate for |
| 4464 | * @data: the page to free |
| 4465 | * |
| 4466 | * Free a page allocated from ring_buffer_alloc_read_page. |
| 4467 | */ |
| 4468 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) |
| 4469 | { |
| 4470 | free_page((unsigned long)data); |
| 4471 | } |
Steven Rostedt | d6ce96d | 2009-05-05 01:15:24 -0400 | [diff] [blame] | 4472 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4473 | |
| 4474 | /** |
| 4475 | * ring_buffer_read_page - extract a page from the ring buffer |
| 4476 | * @buffer: buffer to extract from |
| 4477 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4478 | * @len: amount to extract |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4479 | * @cpu: the cpu of the buffer to extract |
| 4480 | * @full: should the extraction only happen when the page is full. |
| 4481 | * |
| 4482 | * This function will pull out a page from the ring buffer and consume it. |
| 4483 | * @data_page must be the address of the variable that was returned |
| 4484 | * from ring_buffer_alloc_read_page. This is because the page might be used |
| 4485 | * to swap with a page in the ring buffer. |
| 4486 | * |
| 4487 | * for example: |
zhangwei(Jovi) | d611851 | 2013-07-15 16:32:50 +0800 | [diff] [blame] | 4488 | * rpage = ring_buffer_alloc_read_page(buffer, cpu); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4489 | * if (!rpage) |
| 4490 | * return error; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4491 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4492 | * if (ret >= 0) |
| 4493 | * process_page(rpage, ret); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4494 | * |
| 4495 | * When @full is set, the function will not return true unless |
| 4496 | * the writer is off the reader page. |
| 4497 | * |
| 4498 | * Note: it is up to the calling functions to handle sleeps and wakeups. |
| 4499 | * The ring buffer can be used anywhere in the kernel and can not |
| 4500 | * blindly call wake_up. The layer that uses the ring buffer must be |
| 4501 | * responsible for that. |
| 4502 | * |
| 4503 | * Returns: |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4504 | * >=0 if data has been transferred, returns the offset of consumed data. |
| 4505 | * <0 if no data has been transferred. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4506 | */ |
| 4507 | int ring_buffer_read_page(struct ring_buffer *buffer, |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4508 | void **data_page, size_t len, int cpu, int full) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4509 | { |
| 4510 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
| 4511 | struct ring_buffer_event *event; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4512 | struct buffer_data_page *bpage; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4513 | struct buffer_page *reader; |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4514 | unsigned long missed_events; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4515 | unsigned long flags; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4516 | unsigned int commit; |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4517 | unsigned int read; |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 4518 | u64 save_timestamp; |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4519 | int ret = -1; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4520 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4521 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 4522 | goto out; |
| 4523 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4524 | /* |
| 4525 | * If len is not big enough to hold the page header, then |
| 4526 | * we can not copy anything. |
| 4527 | */ |
| 4528 | if (len <= BUF_PAGE_HDR_SIZE) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4529 | goto out; |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4530 | |
| 4531 | len -= BUF_PAGE_HDR_SIZE; |
| 4532 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4533 | if (!data_page) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4534 | goto out; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4535 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4536 | bpage = *data_page; |
| 4537 | if (!bpage) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4538 | goto out; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4539 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4540 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4541 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4542 | reader = rb_get_reader_page(cpu_buffer); |
| 4543 | if (!reader) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4544 | goto out_unlock; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4545 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4546 | event = rb_reader_event(cpu_buffer); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4547 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4548 | read = reader->read; |
| 4549 | commit = rb_page_commit(reader); |
| 4550 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4551 | /* Check if any events were dropped */ |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4552 | missed_events = cpu_buffer->lost_events; |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4553 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4554 | /* |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4555 | * If this page has been partially read or |
| 4556 | * if len is not big enough to read the rest of the page or |
| 4557 | * a writer is still on the page, then |
| 4558 | * we must copy the data from the page to the buffer. |
| 4559 | * Otherwise, we can simply swap the page with the one passed in. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4560 | */ |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4561 | if (read || (len < (commit - read)) || |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4562 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4563 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4564 | unsigned int rpos = read; |
| 4565 | unsigned int pos = 0; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4566 | unsigned int size; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4567 | |
| 4568 | if (full) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4569 | goto out_unlock; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4570 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4571 | if (len > (commit - read)) |
| 4572 | len = (commit - read); |
| 4573 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 4574 | /* Always keep the time extend and data together */ |
| 4575 | size = rb_event_ts_length(event); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4576 | |
| 4577 | if (len < size) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4578 | goto out_unlock; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4579 | |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 4580 | /* save the current timestamp, since the user will need it */ |
| 4581 | save_timestamp = cpu_buffer->read_stamp; |
| 4582 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4583 | /* Need to copy one event at a time */ |
| 4584 | do { |
David Sharp | e1e3592 | 2010-12-22 16:38:24 -0800 | [diff] [blame] | 4585 | /* We need the size of one event, because |
| 4586 | * rb_advance_reader only advances by one event, |
| 4587 | * whereas rb_event_ts_length may include the size of |
| 4588 | * one or two events. |
| 4589 | * We have already ensured there's enough space if this |
| 4590 | * is a time extend. */ |
| 4591 | size = rb_event_length(event); |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4592 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4593 | |
| 4594 | len -= size; |
| 4595 | |
| 4596 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4597 | rpos = reader->read; |
| 4598 | pos += size; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4599 | |
Huang Ying | 18fab91 | 2010-07-28 14:14:01 +0800 | [diff] [blame] | 4600 | if (rpos >= commit) |
| 4601 | break; |
| 4602 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4603 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 4604 | /* Always keep the time extend and data together */ |
| 4605 | size = rb_event_ts_length(event); |
David Sharp | e1e3592 | 2010-12-22 16:38:24 -0800 | [diff] [blame] | 4606 | } while (len >= size); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4607 | |
| 4608 | /* update bpage */ |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4609 | local_set(&bpage->commit, pos); |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 4610 | bpage->time_stamp = save_timestamp; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4611 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4612 | /* we copied everything to the beginning */ |
| 4613 | read = 0; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4614 | } else { |
Steven Rostedt | afbab76 | 2009-05-01 19:40:05 -0400 | [diff] [blame] | 4615 | /* update the entry counter */ |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4616 | cpu_buffer->read += rb_page_entries(reader); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 4617 | cpu_buffer->read_bytes += BUF_PAGE_SIZE; |
Steven Rostedt | afbab76 | 2009-05-01 19:40:05 -0400 | [diff] [blame] | 4618 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4619 | /* swap the pages */ |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4620 | rb_init_page(bpage); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4621 | bpage = reader->page; |
| 4622 | reader->page = *data_page; |
| 4623 | local_set(&reader->write, 0); |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 4624 | local_set(&reader->entries, 0); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4625 | reader->read = 0; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4626 | *data_page = bpage; |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4627 | |
| 4628 | /* |
| 4629 | * Use the real_end for the data size, |
| 4630 | * This gives us a chance to store the lost events |
| 4631 | * on the page. |
| 4632 | */ |
| 4633 | if (reader->real_end) |
| 4634 | local_set(&bpage->commit, reader->real_end); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4635 | } |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4636 | ret = read; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4637 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4638 | cpu_buffer->lost_events = 0; |
Steven Rostedt | 2711ca2 | 2010-05-21 13:32:26 -0400 | [diff] [blame] | 4639 | |
| 4640 | commit = local_read(&bpage->commit); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4641 | /* |
| 4642 | * Set a flag in the commit field if we lost events |
| 4643 | */ |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4644 | if (missed_events) { |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4645 | /* If there is room at the end of the page to save the |
| 4646 | * missed events, then record it there. |
| 4647 | */ |
| 4648 | if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { |
| 4649 | memcpy(&bpage->data[commit], &missed_events, |
| 4650 | sizeof(missed_events)); |
| 4651 | local_add(RB_MISSED_STORED, &bpage->commit); |
Steven Rostedt | 2711ca2 | 2010-05-21 13:32:26 -0400 | [diff] [blame] | 4652 | commit += sizeof(missed_events); |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4653 | } |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4654 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4655 | } |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4656 | |
Steven Rostedt | 2711ca2 | 2010-05-21 13:32:26 -0400 | [diff] [blame] | 4657 | /* |
| 4658 | * This page may be off to user land. Zero it out here. |
| 4659 | */ |
| 4660 | if (commit < BUF_PAGE_SIZE) |
| 4661 | memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); |
| 4662 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4663 | out_unlock: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4664 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4665 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4666 | out: |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4667 | return ret; |
| 4668 | } |
Steven Rostedt | d6ce96d | 2009-05-05 01:15:24 -0400 | [diff] [blame] | 4669 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4670 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 4671 | #ifdef CONFIG_HOTPLUG_CPU |
Frederic Weisbecker | 09c9e84 | 2009-03-21 04:33:36 +0100 | [diff] [blame] | 4672 | static int rb_cpu_notify(struct notifier_block *self, |
| 4673 | unsigned long action, void *hcpu) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4674 | { |
| 4675 | struct ring_buffer *buffer = |
| 4676 | container_of(self, struct ring_buffer, cpu_notify); |
| 4677 | long cpu = (long)hcpu; |
Steven Rostedt (Red Hat) | 9b94a8f | 2016-05-12 11:01:24 -0400 | [diff] [blame] | 4678 | long nr_pages_same; |
| 4679 | int cpu_i; |
| 4680 | unsigned long nr_pages; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4681 | |
| 4682 | switch (action) { |
| 4683 | case CPU_UP_PREPARE: |
| 4684 | case CPU_UP_PREPARE_FROZEN: |
Rusty Russell | 3f237a7 | 2009-06-12 21:15:30 +0930 | [diff] [blame] | 4685 | if (cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4686 | return NOTIFY_OK; |
| 4687 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4688 | nr_pages = 0; |
| 4689 | nr_pages_same = 1; |
| 4690 | /* check if all cpu sizes are same */ |
| 4691 | for_each_buffer_cpu(buffer, cpu_i) { |
| 4692 | /* fill in the size from first enabled cpu */ |
| 4693 | if (nr_pages == 0) |
| 4694 | nr_pages = buffer->buffers[cpu_i]->nr_pages; |
| 4695 | if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { |
| 4696 | nr_pages_same = 0; |
| 4697 | break; |
| 4698 | } |
| 4699 | } |
| 4700 | /* allocate minimum pages, user can later expand it */ |
| 4701 | if (!nr_pages_same) |
| 4702 | nr_pages = 2; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4703 | buffer->buffers[cpu] = |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4704 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4705 | if (!buffer->buffers[cpu]) { |
| 4706 | WARN(1, "failed to allocate ring buffer on CPU %ld\n", |
| 4707 | cpu); |
| 4708 | return NOTIFY_OK; |
| 4709 | } |
| 4710 | smp_wmb(); |
Rusty Russell | 3f237a7 | 2009-06-12 21:15:30 +0930 | [diff] [blame] | 4711 | cpumask_set_cpu(cpu, buffer->cpumask); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4712 | break; |
| 4713 | case CPU_DOWN_PREPARE: |
| 4714 | case CPU_DOWN_PREPARE_FROZEN: |
| 4715 | /* |
| 4716 | * Do nothing. |
| 4717 | * If we were to free the buffer, then the user would |
| 4718 | * lose any trace that was in the buffer. |
| 4719 | */ |
| 4720 | break; |
| 4721 | default: |
| 4722 | break; |
| 4723 | } |
| 4724 | return NOTIFY_OK; |
| 4725 | } |
| 4726 | #endif |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 4727 | |
| 4728 | #ifdef CONFIG_RING_BUFFER_STARTUP_TEST |
| 4729 | /* |
| 4730 | * This is a basic integrity check of the ring buffer. |
| 4731 | * Late in the boot cycle this test will run when configured in. |
| 4732 | * It will kick off a thread per CPU that will go into a loop |
| 4733 | * writing to the per cpu ring buffer various sizes of data. |
| 4734 | * Some of the data will be large items, some small. |
| 4735 | * |
| 4736 | * Another thread is created that goes into a spin, sending out |
| 4737 | * IPIs to the other CPUs to also write into the ring buffer. |
| 4738 | * this is to test the nesting ability of the buffer. |
| 4739 | * |
| 4740 | * Basic stats are recorded and reported. If something in the |
| 4741 | * ring buffer should happen that's not expected, a big warning |
| 4742 | * is displayed and all ring buffers are disabled. |
| 4743 | */ |
| 4744 | static struct task_struct *rb_threads[NR_CPUS] __initdata; |
| 4745 | |
| 4746 | struct rb_test_data { |
| 4747 | struct ring_buffer *buffer; |
| 4748 | unsigned long events; |
| 4749 | unsigned long bytes_written; |
| 4750 | unsigned long bytes_alloc; |
| 4751 | unsigned long bytes_dropped; |
| 4752 | unsigned long events_nested; |
| 4753 | unsigned long bytes_written_nested; |
| 4754 | unsigned long bytes_alloc_nested; |
| 4755 | unsigned long bytes_dropped_nested; |
| 4756 | int min_size_nested; |
| 4757 | int max_size_nested; |
| 4758 | int max_size; |
| 4759 | int min_size; |
| 4760 | int cpu; |
| 4761 | int cnt; |
| 4762 | }; |
| 4763 | |
| 4764 | static struct rb_test_data rb_data[NR_CPUS] __initdata; |
| 4765 | |
| 4766 | /* 1 meg per cpu */ |
| 4767 | #define RB_TEST_BUFFER_SIZE 1048576 |
| 4768 | |
| 4769 | static char rb_string[] __initdata = |
| 4770 | "abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\" |
| 4771 | "?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890" |
| 4772 | "!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv"; |
| 4773 | |
| 4774 | static bool rb_test_started __initdata; |
| 4775 | |
| 4776 | struct rb_item { |
| 4777 | int size; |
| 4778 | char str[]; |
| 4779 | }; |
| 4780 | |
| 4781 | static __init int rb_write_something(struct rb_test_data *data, bool nested) |
| 4782 | { |
| 4783 | struct ring_buffer_event *event; |
| 4784 | struct rb_item *item; |
| 4785 | bool started; |
| 4786 | int event_len; |
| 4787 | int size; |
| 4788 | int len; |
| 4789 | int cnt; |
| 4790 | |
| 4791 | /* Have nested writes different that what is written */ |
| 4792 | cnt = data->cnt + (nested ? 27 : 0); |
| 4793 | |
| 4794 | /* Multiply cnt by ~e, to make some unique increment */ |
| 4795 | size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1); |
| 4796 | |
| 4797 | len = size + sizeof(struct rb_item); |
| 4798 | |
| 4799 | started = rb_test_started; |
| 4800 | /* read rb_test_started before checking buffer enabled */ |
| 4801 | smp_rmb(); |
| 4802 | |
| 4803 | event = ring_buffer_lock_reserve(data->buffer, len); |
| 4804 | if (!event) { |
| 4805 | /* Ignore dropped events before test starts. */ |
| 4806 | if (started) { |
| 4807 | if (nested) |
| 4808 | data->bytes_dropped += len; |
| 4809 | else |
| 4810 | data->bytes_dropped_nested += len; |
| 4811 | } |
| 4812 | return len; |
| 4813 | } |
| 4814 | |
| 4815 | event_len = ring_buffer_event_length(event); |
| 4816 | |
| 4817 | if (RB_WARN_ON(data->buffer, event_len < len)) |
| 4818 | goto out; |
| 4819 | |
| 4820 | item = ring_buffer_event_data(event); |
| 4821 | item->size = size; |
| 4822 | memcpy(item->str, rb_string, size); |
| 4823 | |
| 4824 | if (nested) { |
| 4825 | data->bytes_alloc_nested += event_len; |
| 4826 | data->bytes_written_nested += len; |
| 4827 | data->events_nested++; |
| 4828 | if (!data->min_size_nested || len < data->min_size_nested) |
| 4829 | data->min_size_nested = len; |
| 4830 | if (len > data->max_size_nested) |
| 4831 | data->max_size_nested = len; |
| 4832 | } else { |
| 4833 | data->bytes_alloc += event_len; |
| 4834 | data->bytes_written += len; |
| 4835 | data->events++; |
| 4836 | if (!data->min_size || len < data->min_size) |
| 4837 | data->max_size = len; |
| 4838 | if (len > data->max_size) |
| 4839 | data->max_size = len; |
| 4840 | } |
| 4841 | |
| 4842 | out: |
| 4843 | ring_buffer_unlock_commit(data->buffer, event); |
| 4844 | |
| 4845 | return 0; |
| 4846 | } |
| 4847 | |
| 4848 | static __init int rb_test(void *arg) |
| 4849 | { |
| 4850 | struct rb_test_data *data = arg; |
| 4851 | |
| 4852 | while (!kthread_should_stop()) { |
| 4853 | rb_write_something(data, false); |
| 4854 | data->cnt++; |
| 4855 | |
| 4856 | set_current_state(TASK_INTERRUPTIBLE); |
| 4857 | /* Now sleep between a min of 100-300us and a max of 1ms */ |
| 4858 | usleep_range(((data->cnt % 3) + 1) * 100, 1000); |
| 4859 | } |
| 4860 | |
| 4861 | return 0; |
| 4862 | } |
| 4863 | |
| 4864 | static __init void rb_ipi(void *ignore) |
| 4865 | { |
| 4866 | struct rb_test_data *data; |
| 4867 | int cpu = smp_processor_id(); |
| 4868 | |
| 4869 | data = &rb_data[cpu]; |
| 4870 | rb_write_something(data, true); |
| 4871 | } |
| 4872 | |
| 4873 | static __init int rb_hammer_test(void *arg) |
| 4874 | { |
| 4875 | while (!kthread_should_stop()) { |
| 4876 | |
| 4877 | /* Send an IPI to all cpus to write data! */ |
| 4878 | smp_call_function(rb_ipi, NULL, 1); |
| 4879 | /* No sleep, but for non preempt, let others run */ |
| 4880 | schedule(); |
| 4881 | } |
| 4882 | |
| 4883 | return 0; |
| 4884 | } |
| 4885 | |
| 4886 | static __init int test_ringbuffer(void) |
| 4887 | { |
| 4888 | struct task_struct *rb_hammer; |
| 4889 | struct ring_buffer *buffer; |
| 4890 | int cpu; |
| 4891 | int ret = 0; |
| 4892 | |
| 4893 | pr_info("Running ring buffer tests...\n"); |
| 4894 | |
| 4895 | buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE); |
| 4896 | if (WARN_ON(!buffer)) |
| 4897 | return 0; |
| 4898 | |
| 4899 | /* Disable buffer so that threads can't write to it yet */ |
| 4900 | ring_buffer_record_off(buffer); |
| 4901 | |
| 4902 | for_each_online_cpu(cpu) { |
| 4903 | rb_data[cpu].buffer = buffer; |
| 4904 | rb_data[cpu].cpu = cpu; |
| 4905 | rb_data[cpu].cnt = cpu; |
| 4906 | rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu], |
| 4907 | "rbtester/%d", cpu); |
Wei Yongjun | 703cebf | 2016-06-17 17:33:59 +0000 | [diff] [blame] | 4908 | if (WARN_ON(IS_ERR(rb_threads[cpu]))) { |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 4909 | pr_cont("FAILED\n"); |
Wei Yongjun | 703cebf | 2016-06-17 17:33:59 +0000 | [diff] [blame] | 4910 | ret = PTR_ERR(rb_threads[cpu]); |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 4911 | goto out_free; |
| 4912 | } |
| 4913 | |
| 4914 | kthread_bind(rb_threads[cpu], cpu); |
| 4915 | wake_up_process(rb_threads[cpu]); |
| 4916 | } |
| 4917 | |
| 4918 | /* Now create the rb hammer! */ |
| 4919 | rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer"); |
Wei Yongjun | 703cebf | 2016-06-17 17:33:59 +0000 | [diff] [blame] | 4920 | if (WARN_ON(IS_ERR(rb_hammer))) { |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 4921 | pr_cont("FAILED\n"); |
Wei Yongjun | 703cebf | 2016-06-17 17:33:59 +0000 | [diff] [blame] | 4922 | ret = PTR_ERR(rb_hammer); |
Steven Rostedt (Red Hat) | 6c43e55 | 2013-03-15 11:32:53 -0400 | [diff] [blame] | 4923 | goto out_free; |
| 4924 | } |
| 4925 | |
| 4926 | ring_buffer_record_on(buffer); |
| 4927 | /* |
| 4928 | * Show buffer is enabled before setting rb_test_started. |
| 4929 | * Yes there's a small race window where events could be |
| 4930 | * dropped and the thread wont catch it. But when a ring |
| 4931 | * buffer gets enabled, there will always be some kind of |
| 4932 | * delay before other CPUs see it. Thus, we don't care about |
| 4933 | * those dropped events. We care about events dropped after |
| 4934 | * the threads see that the buffer is active. |
| 4935 | */ |
| 4936 | smp_wmb(); |
| 4937 | rb_test_started = true; |
| 4938 | |
| 4939 | set_current_state(TASK_INTERRUPTIBLE); |
| 4940 | /* Just run for 10 seconds */; |
| 4941 | schedule_timeout(10 * HZ); |
| 4942 | |
| 4943 | kthread_stop(rb_hammer); |
| 4944 | |
| 4945 | out_free: |
| 4946 | for_each_online_cpu(cpu) { |
| 4947 | if (!rb_threads[cpu]) |
| 4948 | break; |
| 4949 | kthread_stop(rb_threads[cpu]); |
| 4950 | } |
| 4951 | if (ret) { |
| 4952 | ring_buffer_free(buffer); |
| 4953 | return ret; |
| 4954 | } |
| 4955 | |
| 4956 | /* Report! */ |
| 4957 | pr_info("finished\n"); |
| 4958 | for_each_online_cpu(cpu) { |
| 4959 | struct ring_buffer_event *event; |
| 4960 | struct rb_test_data *data = &rb_data[cpu]; |
| 4961 | struct rb_item *item; |
| 4962 | unsigned long total_events; |
| 4963 | unsigned long total_dropped; |
| 4964 | unsigned long total_written; |
| 4965 | unsigned long total_alloc; |
| 4966 | unsigned long total_read = 0; |
| 4967 | unsigned long total_size = 0; |
| 4968 | unsigned long total_len = 0; |
| 4969 | unsigned long total_lost = 0; |
| 4970 | unsigned long lost; |
| 4971 | int big_event_size; |
| 4972 | int small_event_size; |
| 4973 | |
| 4974 | ret = -1; |
| 4975 | |
| 4976 | total_events = data->events + data->events_nested; |
| 4977 | total_written = data->bytes_written + data->bytes_written_nested; |
| 4978 | total_alloc = data->bytes_alloc + data->bytes_alloc_nested; |
| 4979 | total_dropped = data->bytes_dropped + data->bytes_dropped_nested; |
| 4980 | |
| 4981 | big_event_size = data->max_size + data->max_size_nested; |
| 4982 | small_event_size = data->min_size + data->min_size_nested; |
| 4983 | |
| 4984 | pr_info("CPU %d:\n", cpu); |
| 4985 | pr_info(" events: %ld\n", total_events); |
| 4986 | pr_info(" dropped bytes: %ld\n", total_dropped); |
| 4987 | pr_info(" alloced bytes: %ld\n", total_alloc); |
| 4988 | pr_info(" written bytes: %ld\n", total_written); |
| 4989 | pr_info(" biggest event: %d\n", big_event_size); |
| 4990 | pr_info(" smallest event: %d\n", small_event_size); |
| 4991 | |
| 4992 | if (RB_WARN_ON(buffer, total_dropped)) |
| 4993 | break; |
| 4994 | |
| 4995 | ret = 0; |
| 4996 | |
| 4997 | while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) { |
| 4998 | total_lost += lost; |
| 4999 | item = ring_buffer_event_data(event); |
| 5000 | total_len += ring_buffer_event_length(event); |
| 5001 | total_size += item->size + sizeof(struct rb_item); |
| 5002 | if (memcmp(&item->str[0], rb_string, item->size) != 0) { |
| 5003 | pr_info("FAILED!\n"); |
| 5004 | pr_info("buffer had: %.*s\n", item->size, item->str); |
| 5005 | pr_info("expected: %.*s\n", item->size, rb_string); |
| 5006 | RB_WARN_ON(buffer, 1); |
| 5007 | ret = -1; |
| 5008 | break; |
| 5009 | } |
| 5010 | total_read++; |
| 5011 | } |
| 5012 | if (ret) |
| 5013 | break; |
| 5014 | |
| 5015 | ret = -1; |
| 5016 | |
| 5017 | pr_info(" read events: %ld\n", total_read); |
| 5018 | pr_info(" lost events: %ld\n", total_lost); |
| 5019 | pr_info(" total events: %ld\n", total_lost + total_read); |
| 5020 | pr_info(" recorded len bytes: %ld\n", total_len); |
| 5021 | pr_info(" recorded size bytes: %ld\n", total_size); |
| 5022 | if (total_lost) |
| 5023 | pr_info(" With dropped events, record len and size may not match\n" |
| 5024 | " alloced and written from above\n"); |
| 5025 | if (!total_lost) { |
| 5026 | if (RB_WARN_ON(buffer, total_len != total_alloc || |
| 5027 | total_size != total_written)) |
| 5028 | break; |
| 5029 | } |
| 5030 | if (RB_WARN_ON(buffer, total_lost + total_read != total_events)) |
| 5031 | break; |
| 5032 | |
| 5033 | ret = 0; |
| 5034 | } |
| 5035 | if (!ret) |
| 5036 | pr_info("Ring buffer PASSED!\n"); |
| 5037 | |
| 5038 | ring_buffer_free(buffer); |
| 5039 | return 0; |
| 5040 | } |
| 5041 | |
| 5042 | late_initcall(test_ringbuffer); |
| 5043 | #endif /* CONFIG_RING_BUFFER_STARTUP_TEST */ |