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 | */ |
| 6 | #include <linux/ring_buffer.h> |
Ingo Molnar | 14131f2 | 2009-02-26 18:47:11 +0100 | [diff] [blame] | 7 | #include <linux/trace_clock.h> |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 8 | #include <linux/ftrace_irq.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 9 | #include <linux/spinlock.h> |
| 10 | #include <linux/debugfs.h> |
| 11 | #include <linux/uaccess.h> |
Steven Rostedt | a81bd80 | 2009-02-06 01:45:16 -0500 | [diff] [blame] | 12 | #include <linux/hardirq.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 13 | #include <linux/module.h> |
| 14 | #include <linux/percpu.h> |
| 15 | #include <linux/mutex.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 16 | #include <linux/init.h> |
| 17 | #include <linux/hash.h> |
| 18 | #include <linux/list.h> |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 19 | #include <linux/cpu.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 20 | #include <linux/fs.h> |
| 21 | |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 22 | #include "trace.h" |
| 23 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 24 | /* |
Steven Rostedt | 5cc9854 | 2009-03-12 22:24:17 -0400 | [diff] [blame^] | 25 | * The ring buffer is made up of a list of pages. A separate list of pages is |
| 26 | * allocated for each CPU. A writer may only write to a buffer that is |
| 27 | * associated with the CPU it is currently executing on. A reader may read |
| 28 | * from any per cpu buffer. |
| 29 | * |
| 30 | * The reader is special. For each per cpu buffer, the reader has its own |
| 31 | * reader page. When a reader has read the entire reader page, this reader |
| 32 | * page is swapped with another page in the ring buffer. |
| 33 | * |
| 34 | * Now, as long as the writer is off the reader page, the reader can do what |
| 35 | * ever it wants with that page. The writer will never write to that page |
| 36 | * again (as long as it is out of the ring buffer). |
| 37 | * |
| 38 | * Here's some silly ASCII art. |
| 39 | * |
| 40 | * +------+ |
| 41 | * |reader| RING BUFFER |
| 42 | * |page | |
| 43 | * +------+ +---+ +---+ +---+ |
| 44 | * | |-->| |-->| | |
| 45 | * +---+ +---+ +---+ |
| 46 | * ^ | |
| 47 | * | | |
| 48 | * +---------------+ |
| 49 | * |
| 50 | * |
| 51 | * +------+ |
| 52 | * |reader| RING BUFFER |
| 53 | * |page |------------------v |
| 54 | * +------+ +---+ +---+ +---+ |
| 55 | * | |-->| |-->| | |
| 56 | * +---+ +---+ +---+ |
| 57 | * ^ | |
| 58 | * | | |
| 59 | * +---------------+ |
| 60 | * |
| 61 | * |
| 62 | * +------+ |
| 63 | * |reader| RING BUFFER |
| 64 | * |page |------------------v |
| 65 | * +------+ +---+ +---+ +---+ |
| 66 | * ^ | |-->| |-->| | |
| 67 | * | +---+ +---+ +---+ |
| 68 | * | | |
| 69 | * | | |
| 70 | * +------------------------------+ |
| 71 | * |
| 72 | * |
| 73 | * +------+ |
| 74 | * |buffer| RING BUFFER |
| 75 | * |page |------------------v |
| 76 | * +------+ +---+ +---+ +---+ |
| 77 | * ^ | | | |-->| | |
| 78 | * | New +---+ +---+ +---+ |
| 79 | * | Reader------^ | |
| 80 | * | page | |
| 81 | * +------------------------------+ |
| 82 | * |
| 83 | * |
| 84 | * After we make this swap, the reader can hand this page off to the splice |
| 85 | * code and be done with it. It can even allocate a new page if it needs to |
| 86 | * and swap that into the ring buffer. |
| 87 | * |
| 88 | * We will be using cmpxchg soon to make all this lockless. |
| 89 | * |
| 90 | */ |
| 91 | |
| 92 | /* |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 93 | * A fast way to enable or disable all ring buffers is to |
| 94 | * call tracing_on or tracing_off. Turning off the ring buffers |
| 95 | * prevents all ring buffers from being recorded to. |
| 96 | * Turning this switch on, makes it OK to write to the |
| 97 | * ring buffer, if the ring buffer is enabled itself. |
| 98 | * |
| 99 | * There's three layers that must be on in order to write |
| 100 | * to the ring buffer. |
| 101 | * |
| 102 | * 1) This global flag must be set. |
| 103 | * 2) The ring buffer must be enabled for recording. |
| 104 | * 3) The per cpu buffer must be enabled for recording. |
| 105 | * |
| 106 | * In case of an anomaly, this global flag has a bit set that |
| 107 | * will permantly disable all ring buffers. |
| 108 | */ |
| 109 | |
| 110 | /* |
| 111 | * Global flag to disable all recording to ring buffers |
| 112 | * This has two bits: ON, DISABLED |
| 113 | * |
| 114 | * ON DISABLED |
| 115 | * ---- ---------- |
| 116 | * 0 0 : ring buffers are off |
| 117 | * 1 0 : ring buffers are on |
| 118 | * X 1 : ring buffers are permanently disabled |
| 119 | */ |
| 120 | |
| 121 | enum { |
| 122 | RB_BUFFERS_ON_BIT = 0, |
| 123 | RB_BUFFERS_DISABLED_BIT = 1, |
| 124 | }; |
| 125 | |
| 126 | enum { |
| 127 | RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, |
| 128 | RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, |
| 129 | }; |
| 130 | |
Hannes Eder | 5e39841 | 2009-02-10 19:44:34 +0100 | [diff] [blame] | 131 | static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 132 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 133 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
| 134 | |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 135 | /** |
| 136 | * tracing_on - enable all tracing buffers |
| 137 | * |
| 138 | * This function enables all tracing buffers that may have been |
| 139 | * disabled with tracing_off. |
| 140 | */ |
| 141 | void tracing_on(void) |
| 142 | { |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 143 | set_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 144 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 145 | EXPORT_SYMBOL_GPL(tracing_on); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 146 | |
| 147 | /** |
| 148 | * tracing_off - turn off all tracing buffers |
| 149 | * |
| 150 | * This function stops all tracing buffers from recording data. |
| 151 | * It does not disable any overhead the tracers themselves may |
| 152 | * be causing. This function simply causes all recording to |
| 153 | * the ring buffers to fail. |
| 154 | */ |
| 155 | void tracing_off(void) |
| 156 | { |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 157 | clear_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
| 158 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 159 | EXPORT_SYMBOL_GPL(tracing_off); |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 160 | |
| 161 | /** |
| 162 | * tracing_off_permanent - permanently disable ring buffers |
| 163 | * |
| 164 | * This function, once called, will disable all ring buffers |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 165 | * permanently. |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 166 | */ |
| 167 | void tracing_off_permanent(void) |
| 168 | { |
| 169 | set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 170 | } |
| 171 | |
Steven Rostedt | 988ae9d | 2009-02-14 19:17:02 -0500 | [diff] [blame] | 172 | /** |
| 173 | * tracing_is_on - show state of ring buffers enabled |
| 174 | */ |
| 175 | int tracing_is_on(void) |
| 176 | { |
| 177 | return ring_buffer_flags == RB_BUFFERS_ON; |
| 178 | } |
| 179 | EXPORT_SYMBOL_GPL(tracing_is_on); |
| 180 | |
Ingo Molnar | d06bbd6 | 2008-11-12 10:11:37 +0100 | [diff] [blame] | 181 | #include "trace.h" |
| 182 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 183 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
| 184 | #define DEBUG_SHIFT 0 |
| 185 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 186 | u64 ring_buffer_time_stamp(int cpu) |
| 187 | { |
Steven Rostedt | 47e74f2 | 2008-11-12 00:01:27 -0500 | [diff] [blame] | 188 | u64 time; |
| 189 | |
| 190 | preempt_disable_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 191 | /* shift to debug/test normalization and TIME_EXTENTS */ |
Ingo Molnar | 14131f2 | 2009-02-26 18:47:11 +0100 | [diff] [blame] | 192 | time = trace_clock_local() << DEBUG_SHIFT; |
Frederic Weisbecker | 2c2d732 | 2008-12-16 22:08:58 +0100 | [diff] [blame] | 193 | preempt_enable_no_resched_notrace(); |
Steven Rostedt | 47e74f2 | 2008-11-12 00:01:27 -0500 | [diff] [blame] | 194 | |
| 195 | return time; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 196 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 197 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 198 | |
| 199 | void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) |
| 200 | { |
| 201 | /* Just stupid testing the normalize function and deltas */ |
| 202 | *ts >>= DEBUG_SHIFT; |
| 203 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 204 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 205 | |
Steven Rostedt | e3d6bf0 | 2009-03-03 13:53:07 -0500 | [diff] [blame] | 206 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 207 | #define RB_ALIGNMENT 4U |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 208 | #define RB_MAX_SMALL_DATA 28 |
| 209 | |
| 210 | enum { |
| 211 | RB_LEN_TIME_EXTEND = 8, |
| 212 | RB_LEN_TIME_STAMP = 16, |
| 213 | }; |
| 214 | |
| 215 | /* inline for ring buffer fast paths */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 216 | static unsigned |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 217 | rb_event_length(struct ring_buffer_event *event) |
| 218 | { |
| 219 | unsigned length; |
| 220 | |
| 221 | switch (event->type) { |
| 222 | case RINGBUF_TYPE_PADDING: |
| 223 | /* undefined */ |
| 224 | return -1; |
| 225 | |
| 226 | case RINGBUF_TYPE_TIME_EXTEND: |
| 227 | return RB_LEN_TIME_EXTEND; |
| 228 | |
| 229 | case RINGBUF_TYPE_TIME_STAMP: |
| 230 | return RB_LEN_TIME_STAMP; |
| 231 | |
| 232 | case RINGBUF_TYPE_DATA: |
| 233 | if (event->len) |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 234 | length = event->len * RB_ALIGNMENT; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 235 | else |
| 236 | length = event->array[0]; |
| 237 | return length + RB_EVNT_HDR_SIZE; |
| 238 | default: |
| 239 | BUG(); |
| 240 | } |
| 241 | /* not hit */ |
| 242 | return 0; |
| 243 | } |
| 244 | |
| 245 | /** |
| 246 | * ring_buffer_event_length - return the length of the event |
| 247 | * @event: the event to get the length of |
| 248 | */ |
| 249 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) |
| 250 | { |
Robert Richter | 465634a | 2009-01-07 15:32:11 +0100 | [diff] [blame] | 251 | unsigned length = rb_event_length(event); |
| 252 | if (event->type != RINGBUF_TYPE_DATA) |
| 253 | return length; |
| 254 | length -= RB_EVNT_HDR_SIZE; |
| 255 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) |
| 256 | length -= sizeof(event->array[0]); |
| 257 | return length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 258 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 259 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 260 | |
| 261 | /* inline for ring buffer fast paths */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 262 | static void * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 263 | rb_event_data(struct ring_buffer_event *event) |
| 264 | { |
| 265 | BUG_ON(event->type != RINGBUF_TYPE_DATA); |
| 266 | /* If length is in len field, then array[0] has the data */ |
| 267 | if (event->len) |
| 268 | return (void *)&event->array[0]; |
| 269 | /* Otherwise length is in array[0] and array[1] has the data */ |
| 270 | return (void *)&event->array[1]; |
| 271 | } |
| 272 | |
| 273 | /** |
| 274 | * ring_buffer_event_data - return the data of the event |
| 275 | * @event: the event to get the data from |
| 276 | */ |
| 277 | void *ring_buffer_event_data(struct ring_buffer_event *event) |
| 278 | { |
| 279 | return rb_event_data(event); |
| 280 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 281 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 282 | |
| 283 | #define for_each_buffer_cpu(buffer, cpu) \ |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 284 | for_each_cpu(cpu, buffer->cpumask) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 285 | |
| 286 | #define TS_SHIFT 27 |
| 287 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) |
| 288 | #define TS_DELTA_TEST (~TS_MASK) |
| 289 | |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 290 | struct buffer_data_page { |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 291 | u64 time_stamp; /* page time stamp */ |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 292 | local_t commit; /* write committed index */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 293 | unsigned char data[]; /* data of buffer page */ |
| 294 | }; |
| 295 | |
| 296 | struct buffer_page { |
| 297 | local_t write; /* index for next write */ |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 298 | unsigned read; /* index for next read */ |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 299 | struct list_head list; /* list of free pages */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 300 | struct buffer_data_page *page; /* Actual data page */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 301 | }; |
| 302 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 303 | static void rb_init_page(struct buffer_data_page *bpage) |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 304 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 305 | local_set(&bpage->commit, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 306 | } |
| 307 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 308 | /** |
| 309 | * ring_buffer_page_len - the size of data on the page. |
| 310 | * @page: The page to read |
| 311 | * |
| 312 | * Returns the amount of data on the page, including buffer page header. |
| 313 | */ |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 314 | size_t ring_buffer_page_len(void *page) |
| 315 | { |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 316 | return local_read(&((struct buffer_data_page *)page)->commit) |
| 317 | + BUF_PAGE_HDR_SIZE; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 318 | } |
| 319 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 320 | /* |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 321 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing |
| 322 | * this issue out. |
| 323 | */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 324 | static void free_buffer_page(struct buffer_page *bpage) |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 325 | { |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 326 | free_page((unsigned long)bpage->page); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 327 | kfree(bpage); |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 328 | } |
| 329 | |
| 330 | /* |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 331 | * We need to fit the time_stamp delta into 27 bits. |
| 332 | */ |
| 333 | static inline int test_time_stamp(u64 delta) |
| 334 | { |
| 335 | if (delta & TS_DELTA_TEST) |
| 336 | return 1; |
| 337 | return 0; |
| 338 | } |
| 339 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 340 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 341 | |
| 342 | /* |
| 343 | * head_page == tail_page && head == tail then buffer is empty. |
| 344 | */ |
| 345 | struct ring_buffer_per_cpu { |
| 346 | int cpu; |
| 347 | struct ring_buffer *buffer; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 348 | spinlock_t reader_lock; /* serialize readers */ |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 349 | raw_spinlock_t lock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 350 | struct lock_class_key lock_key; |
| 351 | struct list_head pages; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 352 | struct buffer_page *head_page; /* read from head */ |
| 353 | struct buffer_page *tail_page; /* write to tail */ |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 354 | struct buffer_page *commit_page; /* committed pages */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 355 | struct buffer_page *reader_page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 356 | unsigned long overrun; |
| 357 | unsigned long entries; |
| 358 | u64 write_stamp; |
| 359 | u64 read_stamp; |
| 360 | atomic_t record_disabled; |
| 361 | }; |
| 362 | |
| 363 | struct ring_buffer { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 364 | unsigned pages; |
| 365 | unsigned flags; |
| 366 | int cpus; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 367 | atomic_t record_disabled; |
Arnaldo Carvalho de Melo | 00f62f6 | 2009-02-09 17:04:06 -0200 | [diff] [blame] | 368 | cpumask_var_t cpumask; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 369 | |
| 370 | struct mutex mutex; |
| 371 | |
| 372 | struct ring_buffer_per_cpu **buffers; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 373 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 374 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 375 | struct notifier_block cpu_notify; |
| 376 | #endif |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 377 | }; |
| 378 | |
| 379 | struct ring_buffer_iter { |
| 380 | struct ring_buffer_per_cpu *cpu_buffer; |
| 381 | unsigned long head; |
| 382 | struct buffer_page *head_page; |
| 383 | u64 read_stamp; |
| 384 | }; |
| 385 | |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 386 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 387 | #define RB_WARN_ON(buffer, cond) \ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 388 | ({ \ |
| 389 | int _____ret = unlikely(cond); \ |
| 390 | if (_____ret) { \ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 391 | atomic_inc(&buffer->record_disabled); \ |
| 392 | WARN_ON(1); \ |
| 393 | } \ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 394 | _____ret; \ |
| 395 | }) |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 396 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 397 | /** |
| 398 | * check_pages - integrity check of buffer pages |
| 399 | * @cpu_buffer: CPU buffer with pages to test |
| 400 | * |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 401 | * 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] | 402 | * been corrupted. |
| 403 | */ |
| 404 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) |
| 405 | { |
| 406 | struct list_head *head = &cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 407 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 408 | |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 409 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
| 410 | return -1; |
| 411 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) |
| 412 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 413 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 414 | list_for_each_entry_safe(bpage, tmp, head, list) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 415 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 416 | bpage->list.next->prev != &bpage->list)) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 417 | return -1; |
| 418 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 419 | bpage->list.prev->next != &bpage->list)) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 420 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 421 | } |
| 422 | |
| 423 | return 0; |
| 424 | } |
| 425 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 426 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
| 427 | unsigned nr_pages) |
| 428 | { |
| 429 | struct list_head *head = &cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 430 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 431 | unsigned long addr; |
| 432 | LIST_HEAD(pages); |
| 433 | unsigned i; |
| 434 | |
| 435 | for (i = 0; i < nr_pages; i++) { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 436 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
Steven Rostedt | aa1e0e3b | 2008-10-02 19:18:09 -0400 | [diff] [blame] | 437 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 438 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 439 | goto free_pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 440 | list_add(&bpage->list, &pages); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 441 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 442 | addr = __get_free_page(GFP_KERNEL); |
| 443 | if (!addr) |
| 444 | goto free_pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 445 | bpage->page = (void *)addr; |
| 446 | rb_init_page(bpage->page); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 447 | } |
| 448 | |
| 449 | list_splice(&pages, head); |
| 450 | |
| 451 | rb_check_pages(cpu_buffer); |
| 452 | |
| 453 | return 0; |
| 454 | |
| 455 | free_pages: |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 456 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
| 457 | list_del_init(&bpage->list); |
| 458 | free_buffer_page(bpage); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 459 | } |
| 460 | return -ENOMEM; |
| 461 | } |
| 462 | |
| 463 | static struct ring_buffer_per_cpu * |
| 464 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) |
| 465 | { |
| 466 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 467 | struct buffer_page *bpage; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 468 | unsigned long addr; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 469 | int ret; |
| 470 | |
| 471 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), |
| 472 | GFP_KERNEL, cpu_to_node(cpu)); |
| 473 | if (!cpu_buffer) |
| 474 | return NULL; |
| 475 | |
| 476 | cpu_buffer->cpu = cpu; |
| 477 | cpu_buffer->buffer = buffer; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 478 | spin_lock_init(&cpu_buffer->reader_lock); |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 479 | cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 480 | INIT_LIST_HEAD(&cpu_buffer->pages); |
| 481 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 482 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 483 | GFP_KERNEL, cpu_to_node(cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 484 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 485 | goto fail_free_buffer; |
| 486 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 487 | cpu_buffer->reader_page = bpage; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 488 | addr = __get_free_page(GFP_KERNEL); |
| 489 | if (!addr) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 490 | goto fail_free_reader; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 491 | bpage->page = (void *)addr; |
| 492 | rb_init_page(bpage->page); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 493 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 494 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 495 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 496 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
| 497 | if (ret < 0) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 498 | goto fail_free_reader; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 499 | |
| 500 | cpu_buffer->head_page |
| 501 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 502 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 503 | |
| 504 | return cpu_buffer; |
| 505 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 506 | fail_free_reader: |
| 507 | free_buffer_page(cpu_buffer->reader_page); |
| 508 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 509 | fail_free_buffer: |
| 510 | kfree(cpu_buffer); |
| 511 | return NULL; |
| 512 | } |
| 513 | |
| 514 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) |
| 515 | { |
| 516 | struct list_head *head = &cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 517 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 518 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 519 | list_del_init(&cpu_buffer->reader_page->list); |
| 520 | free_buffer_page(cpu_buffer->reader_page); |
| 521 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 522 | list_for_each_entry_safe(bpage, tmp, head, list) { |
| 523 | list_del_init(&bpage->list); |
| 524 | free_buffer_page(bpage); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 525 | } |
| 526 | kfree(cpu_buffer); |
| 527 | } |
| 528 | |
Steven Rostedt | a7b1374 | 2008-09-29 23:02:39 -0400 | [diff] [blame] | 529 | /* |
| 530 | * Causes compile errors if the struct buffer_page gets bigger |
| 531 | * than the struct page. |
| 532 | */ |
| 533 | extern int ring_buffer_page_too_big(void); |
| 534 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 535 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 536 | static int __cpuinit rb_cpu_notify(struct notifier_block *self, |
| 537 | unsigned long action, void *hcpu); |
| 538 | #endif |
| 539 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 540 | /** |
| 541 | * ring_buffer_alloc - allocate a new ring_buffer |
Robert Richter | 68814b5 | 2008-11-24 12:24:12 +0100 | [diff] [blame] | 542 | * @size: the size in bytes per cpu that is needed. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 543 | * @flags: attributes to set for the ring buffer. |
| 544 | * |
| 545 | * Currently the only flag that is available is the RB_FL_OVERWRITE |
| 546 | * flag. This flag means that the buffer will overwrite old data |
| 547 | * when the buffer wraps. If this flag is not set, the buffer will |
| 548 | * drop data when the tail hits the head. |
| 549 | */ |
| 550 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) |
| 551 | { |
| 552 | struct ring_buffer *buffer; |
| 553 | int bsize; |
| 554 | int cpu; |
| 555 | |
Steven Rostedt | a7b1374 | 2008-09-29 23:02:39 -0400 | [diff] [blame] | 556 | /* Paranoid! Optimizes out when all is well */ |
| 557 | if (sizeof(struct buffer_page) > sizeof(struct page)) |
| 558 | ring_buffer_page_too_big(); |
| 559 | |
| 560 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 561 | /* keep it in its own cache line */ |
| 562 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), |
| 563 | GFP_KERNEL); |
| 564 | if (!buffer) |
| 565 | return NULL; |
| 566 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 567 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
| 568 | goto fail_free_buffer; |
| 569 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 570 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
| 571 | buffer->flags = flags; |
| 572 | |
| 573 | /* need at least two pages */ |
| 574 | if (buffer->pages == 1) |
| 575 | buffer->pages++; |
| 576 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 577 | get_online_cpus(); |
| 578 | cpumask_copy(buffer->cpumask, cpu_online_mask); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 579 | buffer->cpus = nr_cpu_ids; |
| 580 | |
| 581 | bsize = sizeof(void *) * nr_cpu_ids; |
| 582 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), |
| 583 | GFP_KERNEL); |
| 584 | if (!buffer->buffers) |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 585 | goto fail_free_cpumask; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 586 | |
| 587 | for_each_buffer_cpu(buffer, cpu) { |
| 588 | buffer->buffers[cpu] = |
| 589 | rb_allocate_cpu_buffer(buffer, cpu); |
| 590 | if (!buffer->buffers[cpu]) |
| 591 | goto fail_free_buffers; |
| 592 | } |
| 593 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 594 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 595 | buffer->cpu_notify.notifier_call = rb_cpu_notify; |
| 596 | buffer->cpu_notify.priority = 0; |
| 597 | register_cpu_notifier(&buffer->cpu_notify); |
| 598 | #endif |
| 599 | |
| 600 | put_online_cpus(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 601 | mutex_init(&buffer->mutex); |
| 602 | |
| 603 | return buffer; |
| 604 | |
| 605 | fail_free_buffers: |
| 606 | for_each_buffer_cpu(buffer, cpu) { |
| 607 | if (buffer->buffers[cpu]) |
| 608 | rb_free_cpu_buffer(buffer->buffers[cpu]); |
| 609 | } |
| 610 | kfree(buffer->buffers); |
| 611 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 612 | fail_free_cpumask: |
| 613 | free_cpumask_var(buffer->cpumask); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 614 | put_online_cpus(); |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 615 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 616 | fail_free_buffer: |
| 617 | kfree(buffer); |
| 618 | return NULL; |
| 619 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 620 | EXPORT_SYMBOL_GPL(ring_buffer_alloc); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 621 | |
| 622 | /** |
| 623 | * ring_buffer_free - free a ring buffer. |
| 624 | * @buffer: the buffer to free. |
| 625 | */ |
| 626 | void |
| 627 | ring_buffer_free(struct ring_buffer *buffer) |
| 628 | { |
| 629 | int cpu; |
| 630 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 631 | get_online_cpus(); |
| 632 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 633 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 634 | unregister_cpu_notifier(&buffer->cpu_notify); |
| 635 | #endif |
| 636 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 637 | for_each_buffer_cpu(buffer, cpu) |
| 638 | rb_free_cpu_buffer(buffer->buffers[cpu]); |
| 639 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 640 | put_online_cpus(); |
| 641 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 642 | free_cpumask_var(buffer->cpumask); |
| 643 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 644 | kfree(buffer); |
| 645 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 646 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 647 | |
| 648 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
| 649 | |
| 650 | static void |
| 651 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) |
| 652 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 653 | struct buffer_page *bpage; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 654 | struct list_head *p; |
| 655 | unsigned i; |
| 656 | |
| 657 | atomic_inc(&cpu_buffer->record_disabled); |
| 658 | synchronize_sched(); |
| 659 | |
| 660 | for (i = 0; i < nr_pages; i++) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 661 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
| 662 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 663 | p = cpu_buffer->pages.next; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 664 | bpage = list_entry(p, struct buffer_page, list); |
| 665 | list_del_init(&bpage->list); |
| 666 | free_buffer_page(bpage); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 667 | } |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 668 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
| 669 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 670 | |
| 671 | rb_reset_cpu(cpu_buffer); |
| 672 | |
| 673 | rb_check_pages(cpu_buffer); |
| 674 | |
| 675 | atomic_dec(&cpu_buffer->record_disabled); |
| 676 | |
| 677 | } |
| 678 | |
| 679 | static void |
| 680 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, |
| 681 | struct list_head *pages, unsigned nr_pages) |
| 682 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 683 | struct buffer_page *bpage; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 684 | struct list_head *p; |
| 685 | unsigned i; |
| 686 | |
| 687 | atomic_inc(&cpu_buffer->record_disabled); |
| 688 | synchronize_sched(); |
| 689 | |
| 690 | for (i = 0; i < nr_pages; i++) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 691 | if (RB_WARN_ON(cpu_buffer, list_empty(pages))) |
| 692 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 693 | p = pages->next; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 694 | bpage = list_entry(p, struct buffer_page, list); |
| 695 | list_del_init(&bpage->list); |
| 696 | list_add_tail(&bpage->list, &cpu_buffer->pages); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 697 | } |
| 698 | rb_reset_cpu(cpu_buffer); |
| 699 | |
| 700 | rb_check_pages(cpu_buffer); |
| 701 | |
| 702 | atomic_dec(&cpu_buffer->record_disabled); |
| 703 | } |
| 704 | |
| 705 | /** |
| 706 | * ring_buffer_resize - resize the ring buffer |
| 707 | * @buffer: the buffer to resize. |
| 708 | * @size: the new size. |
| 709 | * |
| 710 | * The tracer is responsible for making sure that the buffer is |
| 711 | * not being used while changing the size. |
| 712 | * Note: We may be able to change the above requirement by using |
| 713 | * RCU synchronizations. |
| 714 | * |
| 715 | * Minimum size is 2 * BUF_PAGE_SIZE. |
| 716 | * |
| 717 | * Returns -1 on failure. |
| 718 | */ |
| 719 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) |
| 720 | { |
| 721 | struct ring_buffer_per_cpu *cpu_buffer; |
| 722 | unsigned nr_pages, rm_pages, new_pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 723 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 724 | unsigned long buffer_size; |
| 725 | unsigned long addr; |
| 726 | LIST_HEAD(pages); |
| 727 | int i, cpu; |
| 728 | |
Ingo Molnar | ee51a1d | 2008-11-13 14:58:31 +0100 | [diff] [blame] | 729 | /* |
| 730 | * Always succeed at resizing a non-existent buffer: |
| 731 | */ |
| 732 | if (!buffer) |
| 733 | return size; |
| 734 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 735 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
| 736 | size *= BUF_PAGE_SIZE; |
| 737 | buffer_size = buffer->pages * BUF_PAGE_SIZE; |
| 738 | |
| 739 | /* we need a minimum of two pages */ |
| 740 | if (size < BUF_PAGE_SIZE * 2) |
| 741 | size = BUF_PAGE_SIZE * 2; |
| 742 | |
| 743 | if (size == buffer_size) |
| 744 | return size; |
| 745 | |
| 746 | mutex_lock(&buffer->mutex); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 747 | get_online_cpus(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 748 | |
| 749 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
| 750 | |
| 751 | if (size < buffer_size) { |
| 752 | |
| 753 | /* easy case, just free pages */ |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 754 | if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) |
| 755 | goto out_fail; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 756 | |
| 757 | rm_pages = buffer->pages - nr_pages; |
| 758 | |
| 759 | for_each_buffer_cpu(buffer, cpu) { |
| 760 | cpu_buffer = buffer->buffers[cpu]; |
| 761 | rb_remove_pages(cpu_buffer, rm_pages); |
| 762 | } |
| 763 | goto out; |
| 764 | } |
| 765 | |
| 766 | /* |
| 767 | * This is a bit more difficult. We only want to add pages |
| 768 | * when we can allocate enough for all CPUs. We do this |
| 769 | * by allocating all the pages and storing them on a local |
| 770 | * link list. If we succeed in our allocation, then we |
| 771 | * add these pages to the cpu_buffers. Otherwise we just free |
| 772 | * them all and return -ENOMEM; |
| 773 | */ |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 774 | if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) |
| 775 | goto out_fail; |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 776 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 777 | new_pages = nr_pages - buffer->pages; |
| 778 | |
| 779 | for_each_buffer_cpu(buffer, cpu) { |
| 780 | for (i = 0; i < new_pages; i++) { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 781 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 782 | cache_line_size()), |
| 783 | GFP_KERNEL, cpu_to_node(cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 784 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 785 | goto free_pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 786 | list_add(&bpage->list, &pages); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 787 | addr = __get_free_page(GFP_KERNEL); |
| 788 | if (!addr) |
| 789 | goto free_pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 790 | bpage->page = (void *)addr; |
| 791 | rb_init_page(bpage->page); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 792 | } |
| 793 | } |
| 794 | |
| 795 | for_each_buffer_cpu(buffer, cpu) { |
| 796 | cpu_buffer = buffer->buffers[cpu]; |
| 797 | rb_insert_pages(cpu_buffer, &pages, new_pages); |
| 798 | } |
| 799 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 800 | if (RB_WARN_ON(buffer, !list_empty(&pages))) |
| 801 | goto out_fail; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 802 | |
| 803 | out: |
| 804 | buffer->pages = nr_pages; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 805 | put_online_cpus(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 806 | mutex_unlock(&buffer->mutex); |
| 807 | |
| 808 | return size; |
| 809 | |
| 810 | free_pages: |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 811 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
| 812 | list_del_init(&bpage->list); |
| 813 | free_buffer_page(bpage); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 814 | } |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 815 | put_online_cpus(); |
Vegard Nossum | 641d2f6 | 2008-11-18 19:22:13 +0100 | [diff] [blame] | 816 | mutex_unlock(&buffer->mutex); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 817 | return -ENOMEM; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 818 | |
| 819 | /* |
| 820 | * Something went totally wrong, and we are too paranoid |
| 821 | * to even clean up the mess. |
| 822 | */ |
| 823 | out_fail: |
| 824 | put_online_cpus(); |
| 825 | mutex_unlock(&buffer->mutex); |
| 826 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 827 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 828 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 829 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 830 | static inline int rb_null_event(struct ring_buffer_event *event) |
| 831 | { |
| 832 | return event->type == RINGBUF_TYPE_PADDING; |
| 833 | } |
| 834 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 835 | static inline void * |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 836 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 837 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 838 | return bpage->data + index; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 839 | } |
| 840 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 841 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 842 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 843 | return bpage->page->data + index; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 844 | } |
| 845 | |
| 846 | static inline struct ring_buffer_event * |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 847 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 848 | { |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 849 | return __rb_page_index(cpu_buffer->reader_page, |
| 850 | cpu_buffer->reader_page->read); |
| 851 | } |
| 852 | |
| 853 | static inline struct ring_buffer_event * |
| 854 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) |
| 855 | { |
| 856 | return __rb_page_index(cpu_buffer->head_page, |
| 857 | cpu_buffer->head_page->read); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 858 | } |
| 859 | |
| 860 | static inline struct ring_buffer_event * |
| 861 | rb_iter_head_event(struct ring_buffer_iter *iter) |
| 862 | { |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 863 | return __rb_page_index(iter->head_page, iter->head); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 864 | } |
| 865 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 866 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
| 867 | { |
| 868 | return local_read(&bpage->write); |
| 869 | } |
| 870 | |
| 871 | static inline unsigned rb_page_commit(struct buffer_page *bpage) |
| 872 | { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 873 | return local_read(&bpage->page->commit); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 874 | } |
| 875 | |
| 876 | /* Size is determined by what has been commited */ |
| 877 | static inline unsigned rb_page_size(struct buffer_page *bpage) |
| 878 | { |
| 879 | return rb_page_commit(bpage); |
| 880 | } |
| 881 | |
| 882 | static inline unsigned |
| 883 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) |
| 884 | { |
| 885 | return rb_page_commit(cpu_buffer->commit_page); |
| 886 | } |
| 887 | |
| 888 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) |
| 889 | { |
| 890 | return rb_page_commit(cpu_buffer->head_page); |
| 891 | } |
| 892 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 893 | /* |
| 894 | * When the tail hits the head and the buffer is in overwrite mode, |
| 895 | * the head jumps to the next page and all content on the previous |
| 896 | * page is discarded. But before doing so, we update the overrun |
| 897 | * variable of the buffer. |
| 898 | */ |
| 899 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) |
| 900 | { |
| 901 | struct ring_buffer_event *event; |
| 902 | unsigned long head; |
| 903 | |
| 904 | for (head = 0; head < rb_head_size(cpu_buffer); |
| 905 | head += rb_event_length(event)) { |
| 906 | |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 907 | event = __rb_page_index(cpu_buffer->head_page, head); |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 908 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
| 909 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 910 | /* Only count data entries */ |
| 911 | if (event->type != RINGBUF_TYPE_DATA) |
| 912 | continue; |
| 913 | cpu_buffer->overrun++; |
| 914 | cpu_buffer->entries--; |
| 915 | } |
| 916 | } |
| 917 | |
| 918 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 919 | struct buffer_page **bpage) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 920 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 921 | struct list_head *p = (*bpage)->list.next; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 922 | |
| 923 | if (p == &cpu_buffer->pages) |
| 924 | p = p->next; |
| 925 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 926 | *bpage = list_entry(p, struct buffer_page, list); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 927 | } |
| 928 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 929 | static inline unsigned |
| 930 | rb_event_index(struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 931 | { |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 932 | unsigned long addr = (unsigned long)event; |
| 933 | |
| 934 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 935 | } |
| 936 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 937 | static int |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 938 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
| 939 | struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 940 | { |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 941 | unsigned long addr = (unsigned long)event; |
| 942 | unsigned long index; |
| 943 | |
| 944 | index = rb_event_index(event); |
| 945 | addr &= PAGE_MASK; |
| 946 | |
| 947 | return cpu_buffer->commit_page->page == (void *)addr && |
| 948 | rb_commit_index(cpu_buffer) == index; |
| 949 | } |
| 950 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 951 | static void |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 952 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
| 953 | struct ring_buffer_event *event) |
| 954 | { |
| 955 | unsigned long addr = (unsigned long)event; |
| 956 | unsigned long index; |
| 957 | |
| 958 | index = rb_event_index(event); |
| 959 | addr &= PAGE_MASK; |
| 960 | |
| 961 | while (cpu_buffer->commit_page->page != (void *)addr) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 962 | if (RB_WARN_ON(cpu_buffer, |
| 963 | cpu_buffer->commit_page == cpu_buffer->tail_page)) |
| 964 | return; |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 965 | cpu_buffer->commit_page->page->commit = |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 966 | cpu_buffer->commit_page->write; |
| 967 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 968 | cpu_buffer->write_stamp = |
| 969 | cpu_buffer->commit_page->page->time_stamp; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 970 | } |
| 971 | |
| 972 | /* Now set the commit to the event's index */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 973 | local_set(&cpu_buffer->commit_page->page->commit, index); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 974 | } |
| 975 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 976 | static void |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 977 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
| 978 | { |
| 979 | /* |
| 980 | * We only race with interrupts and NMIs on this CPU. |
| 981 | * If we own the commit event, then we can commit |
| 982 | * all others that interrupted us, since the interruptions |
| 983 | * are in stack format (they finish before they come |
| 984 | * back to us). This allows us to do a simple loop to |
| 985 | * assign the commit to the tail. |
| 986 | */ |
Steven Rostedt | a8ccf1d | 2008-12-23 11:32:24 -0500 | [diff] [blame] | 987 | again: |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 988 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 989 | cpu_buffer->commit_page->page->commit = |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 990 | cpu_buffer->commit_page->write; |
| 991 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 992 | cpu_buffer->write_stamp = |
| 993 | cpu_buffer->commit_page->page->time_stamp; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 994 | /* add barrier to keep gcc from optimizing too much */ |
| 995 | barrier(); |
| 996 | } |
| 997 | while (rb_commit_index(cpu_buffer) != |
| 998 | rb_page_write(cpu_buffer->commit_page)) { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 999 | cpu_buffer->commit_page->page->commit = |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1000 | cpu_buffer->commit_page->write; |
| 1001 | barrier(); |
| 1002 | } |
Steven Rostedt | a8ccf1d | 2008-12-23 11:32:24 -0500 | [diff] [blame] | 1003 | |
| 1004 | /* again, keep gcc from optimizing */ |
| 1005 | barrier(); |
| 1006 | |
| 1007 | /* |
| 1008 | * If an interrupt came in just after the first while loop |
| 1009 | * and pushed the tail page forward, we will be left with |
| 1010 | * a dangling commit that will never go forward. |
| 1011 | */ |
| 1012 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) |
| 1013 | goto again; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1014 | } |
| 1015 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1016 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1017 | { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1018 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1019 | cpu_buffer->reader_page->read = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1020 | } |
| 1021 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1022 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1023 | { |
| 1024 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 1025 | |
| 1026 | /* |
| 1027 | * The iterator could be on the reader page (it starts there). |
| 1028 | * But the head could have moved, since the reader was |
| 1029 | * found. Check for this case and assign the iterator |
| 1030 | * to the head page instead of next. |
| 1031 | */ |
| 1032 | if (iter->head_page == cpu_buffer->reader_page) |
| 1033 | iter->head_page = cpu_buffer->head_page; |
| 1034 | else |
| 1035 | rb_inc_page(cpu_buffer, &iter->head_page); |
| 1036 | |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1037 | iter->read_stamp = iter->head_page->page->time_stamp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1038 | iter->head = 0; |
| 1039 | } |
| 1040 | |
| 1041 | /** |
| 1042 | * ring_buffer_update_event - update event type and data |
| 1043 | * @event: the even to update |
| 1044 | * @type: the type of event |
| 1045 | * @length: the size of the event field in the ring buffer |
| 1046 | * |
| 1047 | * Update the type and data fields of the event. The length |
| 1048 | * is the actual size that is written to the ring buffer, |
| 1049 | * and with this, we can determine what to place into the |
| 1050 | * data field. |
| 1051 | */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1052 | static void |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1053 | rb_update_event(struct ring_buffer_event *event, |
| 1054 | unsigned type, unsigned length) |
| 1055 | { |
| 1056 | event->type = type; |
| 1057 | |
| 1058 | switch (type) { |
| 1059 | |
| 1060 | case RINGBUF_TYPE_PADDING: |
| 1061 | break; |
| 1062 | |
| 1063 | case RINGBUF_TYPE_TIME_EXTEND: |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1064 | event->len = DIV_ROUND_UP(RB_LEN_TIME_EXTEND, RB_ALIGNMENT); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1065 | break; |
| 1066 | |
| 1067 | case RINGBUF_TYPE_TIME_STAMP: |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1068 | event->len = DIV_ROUND_UP(RB_LEN_TIME_STAMP, RB_ALIGNMENT); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1069 | break; |
| 1070 | |
| 1071 | case RINGBUF_TYPE_DATA: |
| 1072 | length -= RB_EVNT_HDR_SIZE; |
| 1073 | if (length > RB_MAX_SMALL_DATA) { |
| 1074 | event->len = 0; |
| 1075 | event->array[0] = length; |
| 1076 | } else |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1077 | event->len = DIV_ROUND_UP(length, RB_ALIGNMENT); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1078 | break; |
| 1079 | default: |
| 1080 | BUG(); |
| 1081 | } |
| 1082 | } |
| 1083 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1084 | static unsigned rb_calculate_event_length(unsigned length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1085 | { |
| 1086 | struct ring_buffer_event event; /* Used only for sizeof array */ |
| 1087 | |
| 1088 | /* zero length can cause confusions */ |
| 1089 | if (!length) |
| 1090 | length = 1; |
| 1091 | |
| 1092 | if (length > RB_MAX_SMALL_DATA) |
| 1093 | length += sizeof(event.array[0]); |
| 1094 | |
| 1095 | length += RB_EVNT_HDR_SIZE; |
| 1096 | length = ALIGN(length, RB_ALIGNMENT); |
| 1097 | |
| 1098 | return length; |
| 1099 | } |
| 1100 | |
| 1101 | static struct ring_buffer_event * |
| 1102 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, |
| 1103 | unsigned type, unsigned long length, u64 *ts) |
| 1104 | { |
Steven Rostedt | 98db8df | 2008-12-23 11:32:25 -0500 | [diff] [blame] | 1105 | struct buffer_page *tail_page, *head_page, *reader_page, *commit_page; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1106 | unsigned long tail, write; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1107 | struct ring_buffer *buffer = cpu_buffer->buffer; |
| 1108 | struct ring_buffer_event *event; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1109 | unsigned long flags; |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 1110 | bool lock_taken = false; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1111 | |
Steven Rostedt | 98db8df | 2008-12-23 11:32:25 -0500 | [diff] [blame] | 1112 | commit_page = cpu_buffer->commit_page; |
| 1113 | /* we just need to protect against interrupts */ |
| 1114 | barrier(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1115 | tail_page = cpu_buffer->tail_page; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1116 | write = local_add_return(length, &tail_page->write); |
| 1117 | tail = write - length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1118 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1119 | /* See if we shot pass the end of this buffer page */ |
| 1120 | if (write > BUF_PAGE_SIZE) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1121 | struct buffer_page *next_page = tail_page; |
| 1122 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 1123 | local_irq_save(flags); |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 1124 | /* |
Steven Rostedt | a81bd80 | 2009-02-06 01:45:16 -0500 | [diff] [blame] | 1125 | * Since the write to the buffer is still not |
| 1126 | * fully lockless, we must be careful with NMIs. |
| 1127 | * The locks in the writers are taken when a write |
| 1128 | * crosses to a new page. The locks protect against |
| 1129 | * races with the readers (this will soon be fixed |
| 1130 | * with a lockless solution). |
| 1131 | * |
| 1132 | * Because we can not protect against NMIs, and we |
| 1133 | * want to keep traces reentrant, we need to manage |
| 1134 | * what happens when we are in an NMI. |
| 1135 | * |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 1136 | * NMIs can happen after we take the lock. |
| 1137 | * If we are in an NMI, only take the lock |
| 1138 | * if it is not already taken. Otherwise |
| 1139 | * simply fail. |
| 1140 | */ |
Steven Rostedt | a81bd80 | 2009-02-06 01:45:16 -0500 | [diff] [blame] | 1141 | if (unlikely(in_nmi())) { |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 1142 | if (!__raw_spin_trylock(&cpu_buffer->lock)) |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 1143 | goto out_reset; |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 1144 | } else |
| 1145 | __raw_spin_lock(&cpu_buffer->lock); |
| 1146 | |
| 1147 | lock_taken = true; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1148 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1149 | rb_inc_page(cpu_buffer, &next_page); |
| 1150 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1151 | head_page = cpu_buffer->head_page; |
| 1152 | reader_page = cpu_buffer->reader_page; |
| 1153 | |
| 1154 | /* we grabbed the lock before incrementing */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1155 | if (RB_WARN_ON(cpu_buffer, next_page == reader_page)) |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 1156 | goto out_reset; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1157 | |
| 1158 | /* |
| 1159 | * If for some reason, we had an interrupt storm that made |
| 1160 | * it all the way around the buffer, bail, and warn |
| 1161 | * about it. |
| 1162 | */ |
Steven Rostedt | 98db8df | 2008-12-23 11:32:25 -0500 | [diff] [blame] | 1163 | if (unlikely(next_page == commit_page)) { |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1164 | WARN_ON_ONCE(1); |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 1165 | goto out_reset; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1166 | } |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1167 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1168 | if (next_page == head_page) { |
Lai Jiangshan | 6f3b344 | 2009-01-12 11:06:18 +0800 | [diff] [blame] | 1169 | if (!(buffer->flags & RB_FL_OVERWRITE)) |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 1170 | goto out_reset; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1171 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1172 | /* tail_page has not moved yet? */ |
| 1173 | if (tail_page == cpu_buffer->tail_page) { |
| 1174 | /* count overflows */ |
| 1175 | rb_update_overflow(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1176 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1177 | rb_inc_page(cpu_buffer, &head_page); |
| 1178 | cpu_buffer->head_page = head_page; |
| 1179 | cpu_buffer->head_page->read = 0; |
| 1180 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1181 | } |
| 1182 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1183 | /* |
| 1184 | * If the tail page is still the same as what we think |
| 1185 | * it is, then it is up to us to update the tail |
| 1186 | * pointer. |
| 1187 | */ |
| 1188 | if (tail_page == cpu_buffer->tail_page) { |
| 1189 | local_set(&next_page->write, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1190 | local_set(&next_page->page->commit, 0); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1191 | cpu_buffer->tail_page = next_page; |
| 1192 | |
| 1193 | /* reread the time stamp */ |
| 1194 | *ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1195 | cpu_buffer->tail_page->page->time_stamp = *ts; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1196 | } |
| 1197 | |
| 1198 | /* |
| 1199 | * The actual tail page has moved forward. |
| 1200 | */ |
| 1201 | if (tail < BUF_PAGE_SIZE) { |
| 1202 | /* Mark the rest of the page with padding */ |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1203 | event = __rb_page_index(tail_page, tail); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1204 | event->type = RINGBUF_TYPE_PADDING; |
| 1205 | } |
| 1206 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1207 | if (tail <= BUF_PAGE_SIZE) |
| 1208 | /* Set the write back to the previous setting */ |
| 1209 | local_set(&tail_page->write, tail); |
| 1210 | |
| 1211 | /* |
| 1212 | * If this was a commit entry that failed, |
| 1213 | * increment that too |
| 1214 | */ |
| 1215 | if (tail_page == cpu_buffer->commit_page && |
| 1216 | tail == rb_commit_index(cpu_buffer)) { |
| 1217 | rb_set_commit_to_write(cpu_buffer); |
| 1218 | } |
| 1219 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 1220 | __raw_spin_unlock(&cpu_buffer->lock); |
| 1221 | local_irq_restore(flags); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1222 | |
| 1223 | /* fail and let the caller try again */ |
| 1224 | return ERR_PTR(-EAGAIN); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1225 | } |
| 1226 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1227 | /* We reserved something on the buffer */ |
| 1228 | |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1229 | if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE)) |
| 1230 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1231 | |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1232 | event = __rb_page_index(tail_page, tail); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1233 | rb_update_event(event, type, length); |
| 1234 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1235 | /* |
| 1236 | * If this is a commit and the tail is zero, then update |
| 1237 | * this page's time stamp. |
| 1238 | */ |
| 1239 | if (!tail && rb_is_commit(cpu_buffer, event)) |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1240 | cpu_buffer->commit_page->page->time_stamp = *ts; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1241 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1242 | return event; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1243 | |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 1244 | out_reset: |
Lai Jiangshan | 6f3b344 | 2009-01-12 11:06:18 +0800 | [diff] [blame] | 1245 | /* reset write */ |
| 1246 | if (tail <= BUF_PAGE_SIZE) |
| 1247 | local_set(&tail_page->write, tail); |
| 1248 | |
Steven Rostedt | 78d904b | 2009-02-05 18:43:07 -0500 | [diff] [blame] | 1249 | if (likely(lock_taken)) |
| 1250 | __raw_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 1251 | local_irq_restore(flags); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1252 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1253 | } |
| 1254 | |
| 1255 | static int |
| 1256 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
| 1257 | u64 *ts, u64 *delta) |
| 1258 | { |
| 1259 | struct ring_buffer_event *event; |
| 1260 | static int once; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1261 | int ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1262 | |
| 1263 | if (unlikely(*delta > (1ULL << 59) && !once++)) { |
| 1264 | printk(KERN_WARNING "Delta way too big! %llu" |
| 1265 | " ts=%llu write stamp = %llu\n", |
Stephen Rothwell | e2862c9 | 2008-10-27 17:43:28 +1100 | [diff] [blame] | 1266 | (unsigned long long)*delta, |
| 1267 | (unsigned long long)*ts, |
| 1268 | (unsigned long long)cpu_buffer->write_stamp); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1269 | WARN_ON(1); |
| 1270 | } |
| 1271 | |
| 1272 | /* |
| 1273 | * The delta is too big, we to add a |
| 1274 | * new timestamp. |
| 1275 | */ |
| 1276 | event = __rb_reserve_next(cpu_buffer, |
| 1277 | RINGBUF_TYPE_TIME_EXTEND, |
| 1278 | RB_LEN_TIME_EXTEND, |
| 1279 | ts); |
| 1280 | if (!event) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1281 | return -EBUSY; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1282 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1283 | if (PTR_ERR(event) == -EAGAIN) |
| 1284 | return -EAGAIN; |
| 1285 | |
| 1286 | /* Only a commited time event can update the write stamp */ |
| 1287 | if (rb_is_commit(cpu_buffer, event)) { |
| 1288 | /* |
| 1289 | * If this is the first on the page, then we need to |
| 1290 | * update the page itself, and just put in a zero. |
| 1291 | */ |
| 1292 | if (rb_event_index(event)) { |
| 1293 | event->time_delta = *delta & TS_MASK; |
| 1294 | event->array[0] = *delta >> TS_SHIFT; |
| 1295 | } else { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1296 | cpu_buffer->commit_page->page->time_stamp = *ts; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1297 | event->time_delta = 0; |
| 1298 | event->array[0] = 0; |
| 1299 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1300 | cpu_buffer->write_stamp = *ts; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1301 | /* let the caller know this was the commit */ |
| 1302 | ret = 1; |
| 1303 | } else { |
| 1304 | /* Darn, this is just wasted space */ |
| 1305 | event->time_delta = 0; |
| 1306 | event->array[0] = 0; |
| 1307 | ret = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1308 | } |
| 1309 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1310 | *delta = 0; |
| 1311 | |
| 1312 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1313 | } |
| 1314 | |
| 1315 | static struct ring_buffer_event * |
| 1316 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, |
| 1317 | unsigned type, unsigned long length) |
| 1318 | { |
| 1319 | struct ring_buffer_event *event; |
| 1320 | u64 ts, delta; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1321 | int commit = 0; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1322 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1323 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1324 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1325 | /* |
| 1326 | * We allow for interrupts to reenter here and do a trace. |
| 1327 | * If one does, it will cause this original code to loop |
| 1328 | * back here. Even with heavy interrupts happening, this |
| 1329 | * should only happen a few times in a row. If this happens |
| 1330 | * 1000 times in a row, there must be either an interrupt |
| 1331 | * storm or we have something buggy. |
| 1332 | * Bail! |
| 1333 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1334 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1335 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1336 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1337 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
| 1338 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1339 | /* |
| 1340 | * Only the first commit can update the timestamp. |
| 1341 | * Yes there is a race here. If an interrupt comes in |
| 1342 | * just after the conditional and it traces too, then it |
| 1343 | * will also check the deltas. More than one timestamp may |
| 1344 | * also be made. But only the entry that did the actual |
| 1345 | * commit will be something other than zero. |
| 1346 | */ |
| 1347 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && |
| 1348 | rb_page_write(cpu_buffer->tail_page) == |
| 1349 | rb_commit_index(cpu_buffer)) { |
| 1350 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1351 | delta = ts - cpu_buffer->write_stamp; |
| 1352 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1353 | /* make sure this delta is calculated here */ |
| 1354 | barrier(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1355 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1356 | /* Did the write stamp get updated already? */ |
| 1357 | if (unlikely(ts < cpu_buffer->write_stamp)) |
Steven Rostedt | 4143c5c | 2008-11-10 21:46:01 -0500 | [diff] [blame] | 1358 | delta = 0; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1359 | |
| 1360 | if (test_time_stamp(delta)) { |
| 1361 | |
| 1362 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
| 1363 | |
| 1364 | if (commit == -EBUSY) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1365 | return NULL; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1366 | |
| 1367 | if (commit == -EAGAIN) |
| 1368 | goto again; |
| 1369 | |
| 1370 | RB_WARN_ON(cpu_buffer, commit < 0); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1371 | } |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1372 | } else |
| 1373 | /* Non commits have zero deltas */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1374 | delta = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1375 | |
| 1376 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1377 | if (PTR_ERR(event) == -EAGAIN) |
| 1378 | goto again; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1379 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1380 | if (!event) { |
| 1381 | if (unlikely(commit)) |
| 1382 | /* |
| 1383 | * Ouch! We needed a timestamp and it was commited. But |
| 1384 | * we didn't get our event reserved. |
| 1385 | */ |
| 1386 | rb_set_commit_to_write(cpu_buffer); |
| 1387 | return NULL; |
| 1388 | } |
| 1389 | |
| 1390 | /* |
| 1391 | * If the timestamp was commited, make the commit our entry |
| 1392 | * now so that we will update it when needed. |
| 1393 | */ |
| 1394 | if (commit) |
| 1395 | rb_set_commit_event(cpu_buffer, event); |
| 1396 | else if (!rb_is_commit(cpu_buffer, event)) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1397 | delta = 0; |
| 1398 | |
| 1399 | event->time_delta = delta; |
| 1400 | |
| 1401 | return event; |
| 1402 | } |
| 1403 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1404 | static DEFINE_PER_CPU(int, rb_need_resched); |
| 1405 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1406 | /** |
| 1407 | * ring_buffer_lock_reserve - reserve a part of the buffer |
| 1408 | * @buffer: the ring buffer to reserve from |
| 1409 | * @length: the length of the data to reserve (excluding event header) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1410 | * |
| 1411 | * Returns a reseverd event on the ring buffer to copy directly to. |
| 1412 | * The user of this interface will need to get the body to write into |
| 1413 | * and can use the ring_buffer_event_data() interface. |
| 1414 | * |
| 1415 | * The length is the length of the data needed, not the event length |
| 1416 | * which also includes the event header. |
| 1417 | * |
| 1418 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. |
| 1419 | * If NULL is returned, then nothing has been allocated or locked. |
| 1420 | */ |
| 1421 | struct ring_buffer_event * |
Arnaldo Carvalho de Melo | 0a98775 | 2009-02-05 16:12:56 -0200 | [diff] [blame] | 1422 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1423 | { |
| 1424 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1425 | struct ring_buffer_event *event; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1426 | int cpu, resched; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1427 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 1428 | if (ring_buffer_flags != RB_BUFFERS_ON) |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 1429 | return NULL; |
| 1430 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1431 | if (atomic_read(&buffer->record_disabled)) |
| 1432 | return NULL; |
| 1433 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1434 | /* If we are tracing schedule, we don't want to recurse */ |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 1435 | resched = ftrace_preempt_disable(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1436 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1437 | cpu = raw_smp_processor_id(); |
| 1438 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1439 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1440 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1441 | |
| 1442 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1443 | |
| 1444 | if (atomic_read(&cpu_buffer->record_disabled)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1445 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1446 | |
| 1447 | length = rb_calculate_event_length(length); |
| 1448 | if (length > BUF_PAGE_SIZE) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1449 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1450 | |
| 1451 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); |
| 1452 | if (!event) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1453 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1454 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1455 | /* |
| 1456 | * Need to store resched state on this cpu. |
| 1457 | * Only the first needs to. |
| 1458 | */ |
| 1459 | |
| 1460 | if (preempt_count() == 1) |
| 1461 | per_cpu(rb_need_resched, cpu) = resched; |
| 1462 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1463 | return event; |
| 1464 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1465 | out: |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 1466 | ftrace_preempt_enable(resched); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1467 | return NULL; |
| 1468 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1469 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1470 | |
| 1471 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, |
| 1472 | struct ring_buffer_event *event) |
| 1473 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1474 | cpu_buffer->entries++; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1475 | |
| 1476 | /* Only process further if we own the commit */ |
| 1477 | if (!rb_is_commit(cpu_buffer, event)) |
| 1478 | return; |
| 1479 | |
| 1480 | cpu_buffer->write_stamp += event->time_delta; |
| 1481 | |
| 1482 | rb_set_commit_to_write(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1483 | } |
| 1484 | |
| 1485 | /** |
| 1486 | * ring_buffer_unlock_commit - commit a reserved |
| 1487 | * @buffer: The buffer to commit to |
| 1488 | * @event: The event pointer to commit. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1489 | * |
| 1490 | * This commits the data to the ring buffer, and releases any locks held. |
| 1491 | * |
| 1492 | * Must be paired with ring_buffer_lock_reserve. |
| 1493 | */ |
| 1494 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, |
Arnaldo Carvalho de Melo | 0a98775 | 2009-02-05 16:12:56 -0200 | [diff] [blame] | 1495 | struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1496 | { |
| 1497 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1498 | int cpu = raw_smp_processor_id(); |
| 1499 | |
| 1500 | cpu_buffer = buffer->buffers[cpu]; |
| 1501 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1502 | rb_commit(cpu_buffer, event); |
| 1503 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1504 | /* |
| 1505 | * Only the last preempt count needs to restore preemption. |
| 1506 | */ |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 1507 | if (preempt_count() == 1) |
| 1508 | ftrace_preempt_enable(per_cpu(rb_need_resched, cpu)); |
| 1509 | else |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1510 | preempt_enable_no_resched_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1511 | |
| 1512 | return 0; |
| 1513 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1514 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1515 | |
| 1516 | /** |
| 1517 | * ring_buffer_write - write data to the buffer without reserving |
| 1518 | * @buffer: The ring buffer to write to. |
| 1519 | * @length: The length of the data being written (excluding the event header) |
| 1520 | * @data: The data to write to the buffer. |
| 1521 | * |
| 1522 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as |
| 1523 | * one function. If you already have the data to write to the buffer, it |
| 1524 | * may be easier to simply call this function. |
| 1525 | * |
| 1526 | * Note, like ring_buffer_lock_reserve, the length is the length of the data |
| 1527 | * and not the length of the event which would hold the header. |
| 1528 | */ |
| 1529 | int ring_buffer_write(struct ring_buffer *buffer, |
| 1530 | unsigned long length, |
| 1531 | void *data) |
| 1532 | { |
| 1533 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1534 | struct ring_buffer_event *event; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1535 | unsigned long event_length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1536 | void *body; |
| 1537 | int ret = -EBUSY; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1538 | int cpu, resched; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1539 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 1540 | if (ring_buffer_flags != RB_BUFFERS_ON) |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 1541 | return -EBUSY; |
| 1542 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1543 | if (atomic_read(&buffer->record_disabled)) |
| 1544 | return -EBUSY; |
| 1545 | |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 1546 | resched = ftrace_preempt_disable(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1547 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1548 | cpu = raw_smp_processor_id(); |
| 1549 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1550 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1551 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1552 | |
| 1553 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1554 | |
| 1555 | if (atomic_read(&cpu_buffer->record_disabled)) |
| 1556 | goto out; |
| 1557 | |
| 1558 | event_length = rb_calculate_event_length(length); |
| 1559 | event = rb_reserve_next_event(cpu_buffer, |
| 1560 | RINGBUF_TYPE_DATA, event_length); |
| 1561 | if (!event) |
| 1562 | goto out; |
| 1563 | |
| 1564 | body = rb_event_data(event); |
| 1565 | |
| 1566 | memcpy(body, data, length); |
| 1567 | |
| 1568 | rb_commit(cpu_buffer, event); |
| 1569 | |
| 1570 | ret = 0; |
| 1571 | out: |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 1572 | ftrace_preempt_enable(resched); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1573 | |
| 1574 | return ret; |
| 1575 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1576 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1577 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1578 | static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1579 | { |
| 1580 | struct buffer_page *reader = cpu_buffer->reader_page; |
| 1581 | struct buffer_page *head = cpu_buffer->head_page; |
| 1582 | struct buffer_page *commit = cpu_buffer->commit_page; |
| 1583 | |
| 1584 | return reader->read == rb_page_commit(reader) && |
| 1585 | (commit == reader || |
| 1586 | (commit == head && |
| 1587 | head->read == rb_page_commit(commit))); |
| 1588 | } |
| 1589 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1590 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1591 | * ring_buffer_record_disable - stop all writes into the buffer |
| 1592 | * @buffer: The ring buffer to stop writes to. |
| 1593 | * |
| 1594 | * This prevents all writes to the buffer. Any attempt to write |
| 1595 | * to the buffer after this will fail and return NULL. |
| 1596 | * |
| 1597 | * The caller should call synchronize_sched() after this. |
| 1598 | */ |
| 1599 | void ring_buffer_record_disable(struct ring_buffer *buffer) |
| 1600 | { |
| 1601 | atomic_inc(&buffer->record_disabled); |
| 1602 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1603 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1604 | |
| 1605 | /** |
| 1606 | * ring_buffer_record_enable - enable writes to the buffer |
| 1607 | * @buffer: The ring buffer to enable writes |
| 1608 | * |
| 1609 | * Note, multiple disables will need the same number of enables |
| 1610 | * to truely enable the writing (much like preempt_disable). |
| 1611 | */ |
| 1612 | void ring_buffer_record_enable(struct ring_buffer *buffer) |
| 1613 | { |
| 1614 | atomic_dec(&buffer->record_disabled); |
| 1615 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1616 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1617 | |
| 1618 | /** |
| 1619 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer |
| 1620 | * @buffer: The ring buffer to stop writes to. |
| 1621 | * @cpu: The CPU buffer to stop |
| 1622 | * |
| 1623 | * This prevents all writes to the buffer. Any attempt to write |
| 1624 | * to the buffer after this will fail and return NULL. |
| 1625 | * |
| 1626 | * The caller should call synchronize_sched() after this. |
| 1627 | */ |
| 1628 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) |
| 1629 | { |
| 1630 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1631 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1632 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 1633 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1634 | |
| 1635 | cpu_buffer = buffer->buffers[cpu]; |
| 1636 | atomic_inc(&cpu_buffer->record_disabled); |
| 1637 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1638 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1639 | |
| 1640 | /** |
| 1641 | * ring_buffer_record_enable_cpu - enable writes to the buffer |
| 1642 | * @buffer: The ring buffer to enable writes |
| 1643 | * @cpu: The CPU to enable. |
| 1644 | * |
| 1645 | * Note, multiple disables will need the same number of enables |
| 1646 | * to truely enable the writing (much like preempt_disable). |
| 1647 | */ |
| 1648 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) |
| 1649 | { |
| 1650 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1651 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1652 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 1653 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1654 | |
| 1655 | cpu_buffer = buffer->buffers[cpu]; |
| 1656 | atomic_dec(&cpu_buffer->record_disabled); |
| 1657 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1658 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1659 | |
| 1660 | /** |
| 1661 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer |
| 1662 | * @buffer: The ring buffer |
| 1663 | * @cpu: The per CPU buffer to get the entries from. |
| 1664 | */ |
| 1665 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) |
| 1666 | { |
| 1667 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 1668 | unsigned long ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1669 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1670 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 1671 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1672 | |
| 1673 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1674 | ret = cpu_buffer->entries; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1675 | |
| 1676 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1677 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1678 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1679 | |
| 1680 | /** |
| 1681 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer |
| 1682 | * @buffer: The ring buffer |
| 1683 | * @cpu: The per CPU buffer to get the number of overruns from |
| 1684 | */ |
| 1685 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) |
| 1686 | { |
| 1687 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 1688 | unsigned long ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1689 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1690 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 1691 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1692 | |
| 1693 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1694 | ret = cpu_buffer->overrun; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1695 | |
| 1696 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1697 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1698 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1699 | |
| 1700 | /** |
| 1701 | * ring_buffer_entries - get the number of entries in a buffer |
| 1702 | * @buffer: The ring buffer |
| 1703 | * |
| 1704 | * Returns the total number of entries in the ring buffer |
| 1705 | * (all CPU entries) |
| 1706 | */ |
| 1707 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) |
| 1708 | { |
| 1709 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1710 | unsigned long entries = 0; |
| 1711 | int cpu; |
| 1712 | |
| 1713 | /* if you care about this being correct, lock the buffer */ |
| 1714 | for_each_buffer_cpu(buffer, cpu) { |
| 1715 | cpu_buffer = buffer->buffers[cpu]; |
| 1716 | entries += cpu_buffer->entries; |
| 1717 | } |
| 1718 | |
| 1719 | return entries; |
| 1720 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1721 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1722 | |
| 1723 | /** |
| 1724 | * ring_buffer_overrun_cpu - get the number of overruns in buffer |
| 1725 | * @buffer: The ring buffer |
| 1726 | * |
| 1727 | * Returns the total number of overruns in the ring buffer |
| 1728 | * (all CPU entries) |
| 1729 | */ |
| 1730 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) |
| 1731 | { |
| 1732 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1733 | unsigned long overruns = 0; |
| 1734 | int cpu; |
| 1735 | |
| 1736 | /* if you care about this being correct, lock the buffer */ |
| 1737 | for_each_buffer_cpu(buffer, cpu) { |
| 1738 | cpu_buffer = buffer->buffers[cpu]; |
| 1739 | overruns += cpu_buffer->overrun; |
| 1740 | } |
| 1741 | |
| 1742 | return overruns; |
| 1743 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1744 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1745 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 1746 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1747 | { |
| 1748 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 1749 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1750 | /* Iterator usage is expected to have record disabled */ |
| 1751 | if (list_empty(&cpu_buffer->reader_page->list)) { |
| 1752 | iter->head_page = cpu_buffer->head_page; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1753 | iter->head = cpu_buffer->head_page->read; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1754 | } else { |
| 1755 | iter->head_page = cpu_buffer->reader_page; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1756 | iter->head = cpu_buffer->reader_page->read; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1757 | } |
| 1758 | if (iter->head) |
| 1759 | iter->read_stamp = cpu_buffer->read_stamp; |
| 1760 | else |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1761 | iter->read_stamp = iter->head_page->page->time_stamp; |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 1762 | } |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 1763 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 1764 | /** |
| 1765 | * ring_buffer_iter_reset - reset an iterator |
| 1766 | * @iter: The iterator to reset |
| 1767 | * |
| 1768 | * Resets the iterator, so that it will start from the beginning |
| 1769 | * again. |
| 1770 | */ |
| 1771 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) |
| 1772 | { |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1773 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 1774 | unsigned long flags; |
| 1775 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1776 | if (!iter) |
| 1777 | return; |
| 1778 | |
| 1779 | cpu_buffer = iter->cpu_buffer; |
| 1780 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 1781 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 1782 | rb_iter_reset(iter); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 1783 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1784 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1785 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1786 | |
| 1787 | /** |
| 1788 | * ring_buffer_iter_empty - check if an iterator has no more to read |
| 1789 | * @iter: The iterator to check |
| 1790 | */ |
| 1791 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) |
| 1792 | { |
| 1793 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1794 | |
| 1795 | cpu_buffer = iter->cpu_buffer; |
| 1796 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1797 | return iter->head_page == cpu_buffer->commit_page && |
| 1798 | iter->head == rb_commit_index(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1799 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1800 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1801 | |
| 1802 | static void |
| 1803 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
| 1804 | struct ring_buffer_event *event) |
| 1805 | { |
| 1806 | u64 delta; |
| 1807 | |
| 1808 | switch (event->type) { |
| 1809 | case RINGBUF_TYPE_PADDING: |
| 1810 | return; |
| 1811 | |
| 1812 | case RINGBUF_TYPE_TIME_EXTEND: |
| 1813 | delta = event->array[0]; |
| 1814 | delta <<= TS_SHIFT; |
| 1815 | delta += event->time_delta; |
| 1816 | cpu_buffer->read_stamp += delta; |
| 1817 | return; |
| 1818 | |
| 1819 | case RINGBUF_TYPE_TIME_STAMP: |
| 1820 | /* FIXME: not implemented */ |
| 1821 | return; |
| 1822 | |
| 1823 | case RINGBUF_TYPE_DATA: |
| 1824 | cpu_buffer->read_stamp += event->time_delta; |
| 1825 | return; |
| 1826 | |
| 1827 | default: |
| 1828 | BUG(); |
| 1829 | } |
| 1830 | return; |
| 1831 | } |
| 1832 | |
| 1833 | static void |
| 1834 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, |
| 1835 | struct ring_buffer_event *event) |
| 1836 | { |
| 1837 | u64 delta; |
| 1838 | |
| 1839 | switch (event->type) { |
| 1840 | case RINGBUF_TYPE_PADDING: |
| 1841 | return; |
| 1842 | |
| 1843 | case RINGBUF_TYPE_TIME_EXTEND: |
| 1844 | delta = event->array[0]; |
| 1845 | delta <<= TS_SHIFT; |
| 1846 | delta += event->time_delta; |
| 1847 | iter->read_stamp += delta; |
| 1848 | return; |
| 1849 | |
| 1850 | case RINGBUF_TYPE_TIME_STAMP: |
| 1851 | /* FIXME: not implemented */ |
| 1852 | return; |
| 1853 | |
| 1854 | case RINGBUF_TYPE_DATA: |
| 1855 | iter->read_stamp += event->time_delta; |
| 1856 | return; |
| 1857 | |
| 1858 | default: |
| 1859 | BUG(); |
| 1860 | } |
| 1861 | return; |
| 1862 | } |
| 1863 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1864 | static struct buffer_page * |
| 1865 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1866 | { |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1867 | struct buffer_page *reader = NULL; |
| 1868 | unsigned long flags; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1869 | int nr_loops = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1870 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 1871 | local_irq_save(flags); |
| 1872 | __raw_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1873 | |
| 1874 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1875 | /* |
| 1876 | * This should normally only loop twice. But because the |
| 1877 | * start of the reader inserts an empty page, it causes |
| 1878 | * a case where we will loop three times. There should be no |
| 1879 | * reason to loop four times (that I know of). |
| 1880 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1881 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 1882 | reader = NULL; |
| 1883 | goto out; |
| 1884 | } |
| 1885 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1886 | reader = cpu_buffer->reader_page; |
| 1887 | |
| 1888 | /* If there's more to read, return this page */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1889 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1890 | goto out; |
| 1891 | |
| 1892 | /* Never should we have an index greater than the size */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1893 | if (RB_WARN_ON(cpu_buffer, |
| 1894 | cpu_buffer->reader_page->read > rb_page_size(reader))) |
| 1895 | goto out; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1896 | |
| 1897 | /* check if we caught up to the tail */ |
| 1898 | reader = NULL; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1899 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1900 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1901 | |
| 1902 | /* |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1903 | * Splice the empty reader page into the list around the head. |
| 1904 | * Reset the reader page to size zero. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1905 | */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1906 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1907 | reader = cpu_buffer->head_page; |
| 1908 | cpu_buffer->reader_page->list.next = reader->list.next; |
| 1909 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1910 | |
| 1911 | local_set(&cpu_buffer->reader_page->write, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1912 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1913 | |
| 1914 | /* Make the reader page now replace the head */ |
| 1915 | reader->list.prev->next = &cpu_buffer->reader_page->list; |
| 1916 | reader->list.next->prev = &cpu_buffer->reader_page->list; |
| 1917 | |
| 1918 | /* |
| 1919 | * If the tail is on the reader, then we must set the head |
| 1920 | * to the inserted page, otherwise we set it one before. |
| 1921 | */ |
| 1922 | cpu_buffer->head_page = cpu_buffer->reader_page; |
| 1923 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1924 | if (cpu_buffer->commit_page != reader) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1925 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
| 1926 | |
| 1927 | /* Finally update the reader page to the new head */ |
| 1928 | cpu_buffer->reader_page = reader; |
| 1929 | rb_reset_reader_page(cpu_buffer); |
| 1930 | |
| 1931 | goto again; |
| 1932 | |
| 1933 | out: |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 1934 | __raw_spin_unlock(&cpu_buffer->lock); |
| 1935 | local_irq_restore(flags); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1936 | |
| 1937 | return reader; |
| 1938 | } |
| 1939 | |
| 1940 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) |
| 1941 | { |
| 1942 | struct ring_buffer_event *event; |
| 1943 | struct buffer_page *reader; |
| 1944 | unsigned length; |
| 1945 | |
| 1946 | reader = rb_get_reader_page(cpu_buffer); |
| 1947 | |
| 1948 | /* This function should not be called when buffer is empty */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1949 | if (RB_WARN_ON(cpu_buffer, !reader)) |
| 1950 | return; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1951 | |
| 1952 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1953 | |
| 1954 | if (event->type == RINGBUF_TYPE_DATA) |
| 1955 | cpu_buffer->entries--; |
| 1956 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1957 | rb_update_read_stamp(cpu_buffer, event); |
| 1958 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1959 | length = rb_event_length(event); |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1960 | cpu_buffer->reader_page->read += length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1961 | } |
| 1962 | |
| 1963 | static void rb_advance_iter(struct ring_buffer_iter *iter) |
| 1964 | { |
| 1965 | struct ring_buffer *buffer; |
| 1966 | struct ring_buffer_per_cpu *cpu_buffer; |
| 1967 | struct ring_buffer_event *event; |
| 1968 | unsigned length; |
| 1969 | |
| 1970 | cpu_buffer = iter->cpu_buffer; |
| 1971 | buffer = cpu_buffer->buffer; |
| 1972 | |
| 1973 | /* |
| 1974 | * Check if we are at the end of the buffer. |
| 1975 | */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1976 | if (iter->head >= rb_page_size(iter->head_page)) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1977 | if (RB_WARN_ON(buffer, |
| 1978 | iter->head_page == cpu_buffer->commit_page)) |
| 1979 | return; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1980 | rb_inc_iter(iter); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1981 | return; |
| 1982 | } |
| 1983 | |
| 1984 | event = rb_iter_head_event(iter); |
| 1985 | |
| 1986 | length = rb_event_length(event); |
| 1987 | |
| 1988 | /* |
| 1989 | * This should not be called to advance the header if we are |
| 1990 | * at the tail of the buffer. |
| 1991 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1992 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 1993 | (iter->head_page == cpu_buffer->commit_page) && |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 1994 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
| 1995 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1996 | |
| 1997 | rb_update_iter_read_stamp(iter, event); |
| 1998 | |
| 1999 | iter->head += length; |
| 2000 | |
| 2001 | /* check for end of page padding */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2002 | if ((iter->head >= rb_page_size(iter->head_page)) && |
| 2003 | (iter->head_page != cpu_buffer->commit_page)) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2004 | rb_advance_iter(iter); |
| 2005 | } |
| 2006 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2007 | static struct ring_buffer_event * |
| 2008 | rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2009 | { |
| 2010 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2011 | struct ring_buffer_event *event; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2012 | struct buffer_page *reader; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2013 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2014 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2015 | cpu_buffer = buffer->buffers[cpu]; |
| 2016 | |
| 2017 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2018 | /* |
| 2019 | * We repeat when a timestamp is encountered. It is possible |
| 2020 | * to get multiple timestamps from an interrupt entering just |
| 2021 | * as one timestamp is about to be written. The max times |
| 2022 | * that this can happen is the number of nested interrupts we |
| 2023 | * can have. Nesting 10 deep of interrupts is clearly |
| 2024 | * an anomaly. |
| 2025 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 2026 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2027 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2028 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2029 | reader = rb_get_reader_page(cpu_buffer); |
| 2030 | if (!reader) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2031 | return NULL; |
| 2032 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2033 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2034 | |
| 2035 | switch (event->type) { |
| 2036 | case RINGBUF_TYPE_PADDING: |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2037 | RB_WARN_ON(cpu_buffer, 1); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2038 | rb_advance_reader(cpu_buffer); |
| 2039 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2040 | |
| 2041 | case RINGBUF_TYPE_TIME_EXTEND: |
| 2042 | /* Internal data, OK to advance */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2043 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2044 | goto again; |
| 2045 | |
| 2046 | case RINGBUF_TYPE_TIME_STAMP: |
| 2047 | /* FIXME: not implemented */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2048 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2049 | goto again; |
| 2050 | |
| 2051 | case RINGBUF_TYPE_DATA: |
| 2052 | if (ts) { |
| 2053 | *ts = cpu_buffer->read_stamp + event->time_delta; |
| 2054 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); |
| 2055 | } |
| 2056 | return event; |
| 2057 | |
| 2058 | default: |
| 2059 | BUG(); |
| 2060 | } |
| 2061 | |
| 2062 | return NULL; |
| 2063 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2064 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2065 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2066 | static struct ring_buffer_event * |
| 2067 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2068 | { |
| 2069 | struct ring_buffer *buffer; |
| 2070 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2071 | struct ring_buffer_event *event; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2072 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2073 | |
| 2074 | if (ring_buffer_iter_empty(iter)) |
| 2075 | return NULL; |
| 2076 | |
| 2077 | cpu_buffer = iter->cpu_buffer; |
| 2078 | buffer = cpu_buffer->buffer; |
| 2079 | |
| 2080 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2081 | /* |
| 2082 | * We repeat when a timestamp is encountered. It is possible |
| 2083 | * to get multiple timestamps from an interrupt entering just |
| 2084 | * as one timestamp is about to be written. The max times |
| 2085 | * that this can happen is the number of nested interrupts we |
| 2086 | * can have. Nesting 10 deep of interrupts is clearly |
| 2087 | * an anomaly. |
| 2088 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 2089 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2090 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2091 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2092 | if (rb_per_cpu_empty(cpu_buffer)) |
| 2093 | return NULL; |
| 2094 | |
| 2095 | event = rb_iter_head_event(iter); |
| 2096 | |
| 2097 | switch (event->type) { |
| 2098 | case RINGBUF_TYPE_PADDING: |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2099 | rb_inc_iter(iter); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2100 | goto again; |
| 2101 | |
| 2102 | case RINGBUF_TYPE_TIME_EXTEND: |
| 2103 | /* Internal data, OK to advance */ |
| 2104 | rb_advance_iter(iter); |
| 2105 | goto again; |
| 2106 | |
| 2107 | case RINGBUF_TYPE_TIME_STAMP: |
| 2108 | /* FIXME: not implemented */ |
| 2109 | rb_advance_iter(iter); |
| 2110 | goto again; |
| 2111 | |
| 2112 | case RINGBUF_TYPE_DATA: |
| 2113 | if (ts) { |
| 2114 | *ts = iter->read_stamp + event->time_delta; |
| 2115 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); |
| 2116 | } |
| 2117 | return event; |
| 2118 | |
| 2119 | default: |
| 2120 | BUG(); |
| 2121 | } |
| 2122 | |
| 2123 | return NULL; |
| 2124 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2125 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2126 | |
| 2127 | /** |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2128 | * ring_buffer_peek - peek at the next event to be read |
| 2129 | * @buffer: The ring buffer to read |
| 2130 | * @cpu: The cpu to peak at |
| 2131 | * @ts: The timestamp counter of this event. |
| 2132 | * |
| 2133 | * This will return the event that will be read next, but does |
| 2134 | * not consume the data. |
| 2135 | */ |
| 2136 | struct ring_buffer_event * |
| 2137 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) |
| 2138 | { |
| 2139 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2140 | struct ring_buffer_event *event; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2141 | unsigned long flags; |
| 2142 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2143 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2144 | return NULL; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2145 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2146 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 2147 | event = rb_buffer_peek(buffer, cpu, ts); |
| 2148 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
| 2149 | |
| 2150 | return event; |
| 2151 | } |
| 2152 | |
| 2153 | /** |
| 2154 | * ring_buffer_iter_peek - peek at the next event to be read |
| 2155 | * @iter: The ring buffer iterator |
| 2156 | * @ts: The timestamp counter of this event. |
| 2157 | * |
| 2158 | * This will return the event that will be read next, but does |
| 2159 | * not increment the iterator. |
| 2160 | */ |
| 2161 | struct ring_buffer_event * |
| 2162 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) |
| 2163 | { |
| 2164 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 2165 | struct ring_buffer_event *event; |
| 2166 | unsigned long flags; |
| 2167 | |
| 2168 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 2169 | event = rb_iter_peek(iter, ts); |
| 2170 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
| 2171 | |
| 2172 | return event; |
| 2173 | } |
| 2174 | |
| 2175 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2176 | * ring_buffer_consume - return an event and consume it |
| 2177 | * @buffer: The ring buffer to get the next event from |
| 2178 | * |
| 2179 | * Returns the next event in the ring buffer, and that event is consumed. |
| 2180 | * Meaning, that sequential reads will keep returning a different event, |
| 2181 | * and eventually empty the ring buffer if the producer is slower. |
| 2182 | */ |
| 2183 | struct ring_buffer_event * |
| 2184 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) |
| 2185 | { |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2186 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2187 | struct ring_buffer_event *event = NULL; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2188 | unsigned long flags; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2189 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2190 | /* might be called in atomic */ |
| 2191 | preempt_disable(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2192 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2193 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 2194 | goto out; |
| 2195 | |
| 2196 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2197 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2198 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2199 | event = rb_buffer_peek(buffer, cpu, ts); |
| 2200 | if (!event) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2201 | goto out_unlock; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2202 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2203 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2204 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2205 | out_unlock: |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2206 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
| 2207 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2208 | out: |
| 2209 | preempt_enable(); |
| 2210 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2211 | return event; |
| 2212 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2213 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2214 | |
| 2215 | /** |
| 2216 | * ring_buffer_read_start - start a non consuming read of the buffer |
| 2217 | * @buffer: The ring buffer to read from |
| 2218 | * @cpu: The cpu buffer to iterate over |
| 2219 | * |
| 2220 | * This starts up an iteration through the buffer. It also disables |
| 2221 | * the recording to the buffer until the reading is finished. |
| 2222 | * This prevents the reading from being corrupted. This is not |
| 2223 | * a consuming read, so a producer is not expected. |
| 2224 | * |
| 2225 | * Must be paired with ring_buffer_finish. |
| 2226 | */ |
| 2227 | struct ring_buffer_iter * |
| 2228 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) |
| 2229 | { |
| 2230 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2231 | struct ring_buffer_iter *iter; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2232 | unsigned long flags; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2233 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2234 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2235 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2236 | |
| 2237 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
| 2238 | if (!iter) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2239 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2240 | |
| 2241 | cpu_buffer = buffer->buffers[cpu]; |
| 2242 | |
| 2243 | iter->cpu_buffer = cpu_buffer; |
| 2244 | |
| 2245 | atomic_inc(&cpu_buffer->record_disabled); |
| 2246 | synchronize_sched(); |
| 2247 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2248 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 2249 | __raw_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 2250 | rb_iter_reset(iter); |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 2251 | __raw_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2252 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2253 | |
| 2254 | return iter; |
| 2255 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2256 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2257 | |
| 2258 | /** |
| 2259 | * ring_buffer_finish - finish reading the iterator of the buffer |
| 2260 | * @iter: The iterator retrieved by ring_buffer_start |
| 2261 | * |
| 2262 | * This re-enables the recording to the buffer, and frees the |
| 2263 | * iterator. |
| 2264 | */ |
| 2265 | void |
| 2266 | ring_buffer_read_finish(struct ring_buffer_iter *iter) |
| 2267 | { |
| 2268 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 2269 | |
| 2270 | atomic_dec(&cpu_buffer->record_disabled); |
| 2271 | kfree(iter); |
| 2272 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2273 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2274 | |
| 2275 | /** |
| 2276 | * ring_buffer_read - read the next item in the ring buffer by the iterator |
| 2277 | * @iter: The ring buffer iterator |
| 2278 | * @ts: The time stamp of the event read. |
| 2279 | * |
| 2280 | * This reads the next event in the ring buffer and increments the iterator. |
| 2281 | */ |
| 2282 | struct ring_buffer_event * |
| 2283 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) |
| 2284 | { |
| 2285 | struct ring_buffer_event *event; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2286 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 2287 | unsigned long flags; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2288 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2289 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 2290 | event = rb_iter_peek(iter, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2291 | if (!event) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2292 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2293 | |
| 2294 | rb_advance_iter(iter); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2295 | out: |
| 2296 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2297 | |
| 2298 | return event; |
| 2299 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2300 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2301 | |
| 2302 | /** |
| 2303 | * ring_buffer_size - return the size of the ring buffer (in bytes) |
| 2304 | * @buffer: The ring buffer. |
| 2305 | */ |
| 2306 | unsigned long ring_buffer_size(struct ring_buffer *buffer) |
| 2307 | { |
| 2308 | return BUF_PAGE_SIZE * buffer->pages; |
| 2309 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2310 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2311 | |
| 2312 | static void |
| 2313 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) |
| 2314 | { |
| 2315 | cpu_buffer->head_page |
| 2316 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2317 | local_set(&cpu_buffer->head_page->write, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 2318 | local_set(&cpu_buffer->head_page->page->commit, 0); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2319 | |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 2320 | cpu_buffer->head_page->read = 0; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2321 | |
| 2322 | cpu_buffer->tail_page = cpu_buffer->head_page; |
| 2323 | cpu_buffer->commit_page = cpu_buffer->head_page; |
| 2324 | |
| 2325 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
| 2326 | local_set(&cpu_buffer->reader_page->write, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 2327 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 2328 | cpu_buffer->reader_page->read = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2329 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2330 | cpu_buffer->overrun = 0; |
| 2331 | cpu_buffer->entries = 0; |
Steven Rostedt | 69507c0 | 2009-01-21 18:45:57 -0500 | [diff] [blame] | 2332 | |
| 2333 | cpu_buffer->write_stamp = 0; |
| 2334 | cpu_buffer->read_stamp = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2335 | } |
| 2336 | |
| 2337 | /** |
| 2338 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer |
| 2339 | * @buffer: The ring buffer to reset a per cpu buffer of |
| 2340 | * @cpu: The CPU buffer to be reset |
| 2341 | */ |
| 2342 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) |
| 2343 | { |
| 2344 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
| 2345 | unsigned long flags; |
| 2346 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2347 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2348 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2349 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2350 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 2351 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 2352 | __raw_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2353 | |
| 2354 | rb_reset_cpu(cpu_buffer); |
| 2355 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 2356 | __raw_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 2357 | |
| 2358 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2359 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2360 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2361 | |
| 2362 | /** |
| 2363 | * ring_buffer_reset - reset a ring buffer |
| 2364 | * @buffer: The ring buffer to reset all cpu buffers |
| 2365 | */ |
| 2366 | void ring_buffer_reset(struct ring_buffer *buffer) |
| 2367 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2368 | int cpu; |
| 2369 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2370 | for_each_buffer_cpu(buffer, cpu) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2371 | ring_buffer_reset_cpu(buffer, cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2372 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2373 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2374 | |
| 2375 | /** |
| 2376 | * rind_buffer_empty - is the ring buffer empty? |
| 2377 | * @buffer: The ring buffer to test |
| 2378 | */ |
| 2379 | int ring_buffer_empty(struct ring_buffer *buffer) |
| 2380 | { |
| 2381 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2382 | int cpu; |
| 2383 | |
| 2384 | /* yes this is racy, but if you don't like the race, lock the buffer */ |
| 2385 | for_each_buffer_cpu(buffer, cpu) { |
| 2386 | cpu_buffer = buffer->buffers[cpu]; |
| 2387 | if (!rb_per_cpu_empty(cpu_buffer)) |
| 2388 | return 0; |
| 2389 | } |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2390 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2391 | return 1; |
| 2392 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2393 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2394 | |
| 2395 | /** |
| 2396 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? |
| 2397 | * @buffer: The ring buffer |
| 2398 | * @cpu: The CPU buffer to test |
| 2399 | */ |
| 2400 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) |
| 2401 | { |
| 2402 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2403 | int ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2404 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2405 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2406 | return 1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2407 | |
| 2408 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2409 | ret = rb_per_cpu_empty(cpu_buffer); |
| 2410 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2411 | |
| 2412 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2413 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2414 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2415 | |
| 2416 | /** |
| 2417 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers |
| 2418 | * @buffer_a: One buffer to swap with |
| 2419 | * @buffer_b: The other buffer to swap with |
| 2420 | * |
| 2421 | * This function is useful for tracers that want to take a "snapshot" |
| 2422 | * of a CPU buffer and has another back up buffer lying around. |
| 2423 | * it is expected that the tracer handles the cpu buffer not being |
| 2424 | * used at the moment. |
| 2425 | */ |
| 2426 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, |
| 2427 | struct ring_buffer *buffer_b, int cpu) |
| 2428 | { |
| 2429 | struct ring_buffer_per_cpu *cpu_buffer_a; |
| 2430 | struct ring_buffer_per_cpu *cpu_buffer_b; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2431 | int ret = -EINVAL; |
| 2432 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2433 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
| 2434 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2435 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2436 | |
| 2437 | /* At least make sure the two buffers are somewhat the same */ |
Lai Jiangshan | 6d102bc | 2008-12-17 17:48:23 +0800 | [diff] [blame] | 2438 | if (buffer_a->pages != buffer_b->pages) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2439 | goto out; |
| 2440 | |
| 2441 | ret = -EAGAIN; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2442 | |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2443 | if (ring_buffer_flags != RB_BUFFERS_ON) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2444 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2445 | |
| 2446 | if (atomic_read(&buffer_a->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2447 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2448 | |
| 2449 | if (atomic_read(&buffer_b->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2450 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2451 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2452 | cpu_buffer_a = buffer_a->buffers[cpu]; |
| 2453 | cpu_buffer_b = buffer_b->buffers[cpu]; |
| 2454 | |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2455 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2456 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2457 | |
| 2458 | if (atomic_read(&cpu_buffer_b->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2459 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 2460 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2461 | /* |
| 2462 | * We can't do a synchronize_sched here because this |
| 2463 | * function can be called in atomic context. |
| 2464 | * Normally this will be called from the same CPU as cpu. |
| 2465 | * If not it's up to the caller to protect this. |
| 2466 | */ |
| 2467 | atomic_inc(&cpu_buffer_a->record_disabled); |
| 2468 | atomic_inc(&cpu_buffer_b->record_disabled); |
| 2469 | |
| 2470 | buffer_a->buffers[cpu] = cpu_buffer_b; |
| 2471 | buffer_b->buffers[cpu] = cpu_buffer_a; |
| 2472 | |
| 2473 | cpu_buffer_b->buffer = buffer_a; |
| 2474 | cpu_buffer_a->buffer = buffer_b; |
| 2475 | |
| 2476 | atomic_dec(&cpu_buffer_a->record_disabled); |
| 2477 | atomic_dec(&cpu_buffer_b->record_disabled); |
| 2478 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2479 | ret = 0; |
| 2480 | out: |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2481 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2482 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2483 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2484 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2485 | static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer, |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2486 | struct buffer_data_page *bpage, |
| 2487 | unsigned int offset) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2488 | { |
| 2489 | struct ring_buffer_event *event; |
| 2490 | unsigned long head; |
| 2491 | |
| 2492 | __raw_spin_lock(&cpu_buffer->lock); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2493 | for (head = offset; head < local_read(&bpage->commit); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2494 | head += rb_event_length(event)) { |
| 2495 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2496 | event = __rb_data_page_index(bpage, head); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2497 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
| 2498 | return; |
| 2499 | /* Only count data entries */ |
| 2500 | if (event->type != RINGBUF_TYPE_DATA) |
| 2501 | continue; |
| 2502 | cpu_buffer->entries--; |
| 2503 | } |
| 2504 | __raw_spin_unlock(&cpu_buffer->lock); |
| 2505 | } |
| 2506 | |
| 2507 | /** |
| 2508 | * ring_buffer_alloc_read_page - allocate a page to read from buffer |
| 2509 | * @buffer: the buffer to allocate for. |
| 2510 | * |
| 2511 | * This function is used in conjunction with ring_buffer_read_page. |
| 2512 | * When reading a full page from the ring buffer, these functions |
| 2513 | * can be used to speed up the process. The calling function should |
| 2514 | * allocate a few pages first with this function. Then when it |
| 2515 | * needs to get pages from the ring buffer, it passes the result |
| 2516 | * of this function into ring_buffer_read_page, which will swap |
| 2517 | * the page that was allocated, with the read page of the buffer. |
| 2518 | * |
| 2519 | * Returns: |
| 2520 | * The page allocated, or NULL on error. |
| 2521 | */ |
| 2522 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) |
| 2523 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2524 | struct buffer_data_page *bpage; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2525 | unsigned long addr; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2526 | |
| 2527 | addr = __get_free_page(GFP_KERNEL); |
| 2528 | if (!addr) |
| 2529 | return NULL; |
| 2530 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2531 | bpage = (void *)addr; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2532 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2533 | rb_init_page(bpage); |
| 2534 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2535 | return bpage; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2536 | } |
| 2537 | |
| 2538 | /** |
| 2539 | * ring_buffer_free_read_page - free an allocated read page |
| 2540 | * @buffer: the buffer the page was allocate for |
| 2541 | * @data: the page to free |
| 2542 | * |
| 2543 | * Free a page allocated from ring_buffer_alloc_read_page. |
| 2544 | */ |
| 2545 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) |
| 2546 | { |
| 2547 | free_page((unsigned long)data); |
| 2548 | } |
| 2549 | |
| 2550 | /** |
| 2551 | * ring_buffer_read_page - extract a page from the ring buffer |
| 2552 | * @buffer: buffer to extract from |
| 2553 | * @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] | 2554 | * @len: amount to extract |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2555 | * @cpu: the cpu of the buffer to extract |
| 2556 | * @full: should the extraction only happen when the page is full. |
| 2557 | * |
| 2558 | * This function will pull out a page from the ring buffer and consume it. |
| 2559 | * @data_page must be the address of the variable that was returned |
| 2560 | * from ring_buffer_alloc_read_page. This is because the page might be used |
| 2561 | * to swap with a page in the ring buffer. |
| 2562 | * |
| 2563 | * for example: |
Lai Jiangshan | b85fa01 | 2009-02-09 14:21:14 +0800 | [diff] [blame] | 2564 | * rpage = ring_buffer_alloc_read_page(buffer); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2565 | * if (!rpage) |
| 2566 | * return error; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2567 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2568 | * if (ret >= 0) |
| 2569 | * process_page(rpage, ret); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2570 | * |
| 2571 | * When @full is set, the function will not return true unless |
| 2572 | * the writer is off the reader page. |
| 2573 | * |
| 2574 | * Note: it is up to the calling functions to handle sleeps and wakeups. |
| 2575 | * The ring buffer can be used anywhere in the kernel and can not |
| 2576 | * blindly call wake_up. The layer that uses the ring buffer must be |
| 2577 | * responsible for that. |
| 2578 | * |
| 2579 | * Returns: |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2580 | * >=0 if data has been transferred, returns the offset of consumed data. |
| 2581 | * <0 if no data has been transferred. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2582 | */ |
| 2583 | int ring_buffer_read_page(struct ring_buffer *buffer, |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2584 | void **data_page, size_t len, int cpu, int full) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2585 | { |
| 2586 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
| 2587 | struct ring_buffer_event *event; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2588 | struct buffer_data_page *bpage; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2589 | struct buffer_page *reader; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2590 | unsigned long flags; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2591 | unsigned int commit; |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2592 | unsigned int read; |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 2593 | u64 save_timestamp; |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2594 | int ret = -1; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2595 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2596 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 2597 | goto out; |
| 2598 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2599 | /* |
| 2600 | * If len is not big enough to hold the page header, then |
| 2601 | * we can not copy anything. |
| 2602 | */ |
| 2603 | if (len <= BUF_PAGE_HDR_SIZE) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2604 | goto out; |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2605 | |
| 2606 | len -= BUF_PAGE_HDR_SIZE; |
| 2607 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2608 | if (!data_page) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2609 | goto out; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2610 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2611 | bpage = *data_page; |
| 2612 | if (!bpage) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2613 | goto out; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2614 | |
| 2615 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
| 2616 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2617 | reader = rb_get_reader_page(cpu_buffer); |
| 2618 | if (!reader) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2619 | goto out_unlock; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2620 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2621 | event = rb_reader_event(cpu_buffer); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2622 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2623 | read = reader->read; |
| 2624 | commit = rb_page_commit(reader); |
| 2625 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2626 | /* |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2627 | * If this page has been partially read or |
| 2628 | * if len is not big enough to read the rest of the page or |
| 2629 | * a writer is still on the page, then |
| 2630 | * we must copy the data from the page to the buffer. |
| 2631 | * Otherwise, we can simply swap the page with the one passed in. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2632 | */ |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2633 | if (read || (len < (commit - read)) || |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2634 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2635 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2636 | unsigned int rpos = read; |
| 2637 | unsigned int pos = 0; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2638 | unsigned int size; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2639 | |
| 2640 | if (full) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2641 | goto out_unlock; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2642 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2643 | if (len > (commit - read)) |
| 2644 | len = (commit - read); |
| 2645 | |
| 2646 | size = rb_event_length(event); |
| 2647 | |
| 2648 | if (len < size) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2649 | goto out_unlock; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2650 | |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 2651 | /* save the current timestamp, since the user will need it */ |
| 2652 | save_timestamp = cpu_buffer->read_stamp; |
| 2653 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2654 | /* Need to copy one event at a time */ |
| 2655 | do { |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2656 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2657 | |
| 2658 | len -= size; |
| 2659 | |
| 2660 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2661 | rpos = reader->read; |
| 2662 | pos += size; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2663 | |
| 2664 | event = rb_reader_event(cpu_buffer); |
| 2665 | size = rb_event_length(event); |
| 2666 | } while (len > size); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2667 | |
| 2668 | /* update bpage */ |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2669 | local_set(&bpage->commit, pos); |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 2670 | bpage->time_stamp = save_timestamp; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2671 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 2672 | /* we copied everything to the beginning */ |
| 2673 | read = 0; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2674 | } else { |
| 2675 | /* swap the pages */ |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2676 | rb_init_page(bpage); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2677 | bpage = reader->page; |
| 2678 | reader->page = *data_page; |
| 2679 | local_set(&reader->write, 0); |
| 2680 | reader->read = 0; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 2681 | *data_page = bpage; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 2682 | |
| 2683 | /* update the entry counter */ |
| 2684 | rb_remove_entries(cpu_buffer, bpage, read); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2685 | } |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 2686 | ret = read; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2687 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2688 | out_unlock: |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2689 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
| 2690 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2691 | out: |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 2692 | return ret; |
| 2693 | } |
| 2694 | |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2695 | static ssize_t |
| 2696 | rb_simple_read(struct file *filp, char __user *ubuf, |
| 2697 | size_t cnt, loff_t *ppos) |
| 2698 | { |
Hannes Eder | 5e39841 | 2009-02-10 19:44:34 +0100 | [diff] [blame] | 2699 | unsigned long *p = filp->private_data; |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2700 | char buf[64]; |
| 2701 | int r; |
| 2702 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 2703 | if (test_bit(RB_BUFFERS_DISABLED_BIT, p)) |
| 2704 | r = sprintf(buf, "permanently disabled\n"); |
| 2705 | else |
| 2706 | r = sprintf(buf, "%d\n", test_bit(RB_BUFFERS_ON_BIT, p)); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2707 | |
| 2708 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); |
| 2709 | } |
| 2710 | |
| 2711 | static ssize_t |
| 2712 | rb_simple_write(struct file *filp, const char __user *ubuf, |
| 2713 | size_t cnt, loff_t *ppos) |
| 2714 | { |
Hannes Eder | 5e39841 | 2009-02-10 19:44:34 +0100 | [diff] [blame] | 2715 | unsigned long *p = filp->private_data; |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2716 | char buf[64]; |
Hannes Eder | 5e39841 | 2009-02-10 19:44:34 +0100 | [diff] [blame] | 2717 | unsigned long val; |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2718 | int ret; |
| 2719 | |
| 2720 | if (cnt >= sizeof(buf)) |
| 2721 | return -EINVAL; |
| 2722 | |
| 2723 | if (copy_from_user(&buf, ubuf, cnt)) |
| 2724 | return -EFAULT; |
| 2725 | |
| 2726 | buf[cnt] = 0; |
| 2727 | |
| 2728 | ret = strict_strtoul(buf, 10, &val); |
| 2729 | if (ret < 0) |
| 2730 | return ret; |
| 2731 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 2732 | if (val) |
| 2733 | set_bit(RB_BUFFERS_ON_BIT, p); |
| 2734 | else |
| 2735 | clear_bit(RB_BUFFERS_ON_BIT, p); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2736 | |
| 2737 | (*ppos)++; |
| 2738 | |
| 2739 | return cnt; |
| 2740 | } |
| 2741 | |
Steven Rostedt | 5e2336a | 2009-03-05 21:44:55 -0500 | [diff] [blame] | 2742 | static const struct file_operations rb_simple_fops = { |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2743 | .open = tracing_open_generic, |
| 2744 | .read = rb_simple_read, |
| 2745 | .write = rb_simple_write, |
| 2746 | }; |
| 2747 | |
| 2748 | |
| 2749 | static __init int rb_init_debugfs(void) |
| 2750 | { |
| 2751 | struct dentry *d_tracer; |
| 2752 | struct dentry *entry; |
| 2753 | |
| 2754 | d_tracer = tracing_init_dentry(); |
| 2755 | |
| 2756 | entry = debugfs_create_file("tracing_on", 0644, d_tracer, |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 2757 | &ring_buffer_flags, &rb_simple_fops); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2758 | if (!entry) |
| 2759 | pr_warning("Could not create debugfs 'tracing_on' entry\n"); |
| 2760 | |
| 2761 | return 0; |
| 2762 | } |
| 2763 | |
| 2764 | fs_initcall(rb_init_debugfs); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2765 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 2766 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2767 | static int __cpuinit rb_cpu_notify(struct notifier_block *self, |
| 2768 | unsigned long action, void *hcpu) |
| 2769 | { |
| 2770 | struct ring_buffer *buffer = |
| 2771 | container_of(self, struct ring_buffer, cpu_notify); |
| 2772 | long cpu = (long)hcpu; |
| 2773 | |
| 2774 | switch (action) { |
| 2775 | case CPU_UP_PREPARE: |
| 2776 | case CPU_UP_PREPARE_FROZEN: |
| 2777 | if (cpu_isset(cpu, *buffer->cpumask)) |
| 2778 | return NOTIFY_OK; |
| 2779 | |
| 2780 | buffer->buffers[cpu] = |
| 2781 | rb_allocate_cpu_buffer(buffer, cpu); |
| 2782 | if (!buffer->buffers[cpu]) { |
| 2783 | WARN(1, "failed to allocate ring buffer on CPU %ld\n", |
| 2784 | cpu); |
| 2785 | return NOTIFY_OK; |
| 2786 | } |
| 2787 | smp_wmb(); |
| 2788 | cpu_set(cpu, *buffer->cpumask); |
| 2789 | break; |
| 2790 | case CPU_DOWN_PREPARE: |
| 2791 | case CPU_DOWN_PREPARE_FROZEN: |
| 2792 | /* |
| 2793 | * Do nothing. |
| 2794 | * If we were to free the buffer, then the user would |
| 2795 | * lose any trace that was in the buffer. |
| 2796 | */ |
| 2797 | break; |
| 2798 | default: |
| 2799 | break; |
| 2800 | } |
| 2801 | return NOTIFY_OK; |
| 2802 | } |
| 2803 | #endif |