Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Tty buffer allocation management |
| 3 | */ |
| 4 | |
| 5 | #include <linux/types.h> |
| 6 | #include <linux/errno.h> |
| 7 | #include <linux/tty.h> |
| 8 | #include <linux/tty_driver.h> |
| 9 | #include <linux/tty_flip.h> |
| 10 | #include <linux/timer.h> |
| 11 | #include <linux/string.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/sched.h> |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 14 | #include <linux/wait.h> |
| 15 | #include <linux/bitops.h> |
| 16 | #include <linux/delay.h> |
| 17 | #include <linux/module.h> |
George Spelvin | 593fb1ae4 | 2013-02-12 02:00:43 -0500 | [diff] [blame] | 18 | #include <linux/ratelimit.h> |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 19 | |
Peter Hurley | 1cef50e | 2013-06-15 09:36:02 -0400 | [diff] [blame] | 20 | |
| 21 | #define MIN_TTYB_SIZE 256 |
| 22 | #define TTYB_ALIGN_MASK 255 |
| 23 | |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 24 | /* |
| 25 | * Byte threshold to limit memory consumption for flip buffers. |
| 26 | * The actual memory limit is > 2x this amount. |
| 27 | */ |
Peter Hurley | 4d18e6ef | 2013-11-22 12:09:55 -0500 | [diff] [blame] | 28 | #define TTYB_DEFAULT_MEM_LIMIT 65536 |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 29 | |
Peter Hurley | 9114fe8 | 2013-06-15 09:36:16 -0400 | [diff] [blame] | 30 | /* |
| 31 | * We default to dicing tty buffer allocations to this many characters |
| 32 | * in order to avoid multiple page allocations. We know the size of |
| 33 | * tty_buffer itself but it must also be taken into account that the |
| 34 | * the buffer is 256 byte aligned. See tty_buffer_find for the allocation |
| 35 | * logic this must match |
| 36 | */ |
| 37 | |
| 38 | #define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF) |
| 39 | |
Peter Hurley | 1a48632 | 2015-04-13 13:24:34 -0400 | [diff] [blame] | 40 | /* |
| 41 | * If all tty flip buffers have been processed by flush_to_ldisc() or |
| 42 | * dropped by tty_buffer_flush(), check if the linked pty has been closed. |
| 43 | * If so, wake the reader/poll to process |
| 44 | */ |
| 45 | static inline void check_other_closed(struct tty_struct *tty) |
| 46 | { |
| 47 | unsigned long flags, old; |
| 48 | |
| 49 | /* transition from TTY_OTHER_CLOSED => TTY_OTHER_DONE must be atomic */ |
| 50 | for (flags = ACCESS_ONCE(tty->flags); |
| 51 | test_bit(TTY_OTHER_CLOSED, &flags); |
| 52 | ) { |
| 53 | old = flags; |
| 54 | __set_bit(TTY_OTHER_DONE, &flags); |
| 55 | flags = cmpxchg(&tty->flags, old, flags); |
| 56 | if (old == flags) { |
| 57 | wake_up_interruptible(&tty->read_wait); |
| 58 | break; |
| 59 | } |
| 60 | } |
| 61 | } |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 62 | |
| 63 | /** |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 64 | * tty_buffer_lock_exclusive - gain exclusive access to buffer |
| 65 | * tty_buffer_unlock_exclusive - release exclusive access |
| 66 | * |
| 67 | * @port - tty_port owning the flip buffer |
| 68 | * |
| 69 | * Guarantees safe use of the line discipline's receive_buf() method by |
| 70 | * excluding the buffer work and any pending flush from using the flip |
| 71 | * buffer. Data can continue to be added concurrently to the flip buffer |
| 72 | * from the driver side. |
| 73 | * |
| 74 | * On release, the buffer work is restarted if there is data in the |
| 75 | * flip buffer |
| 76 | */ |
| 77 | |
| 78 | void tty_buffer_lock_exclusive(struct tty_port *port) |
| 79 | { |
| 80 | struct tty_bufhead *buf = &port->buf; |
| 81 | |
| 82 | atomic_inc(&buf->priority); |
| 83 | mutex_lock(&buf->lock); |
| 84 | } |
Ben Hutchings | 28a821c | 2014-05-19 01:03:06 +0100 | [diff] [blame] | 85 | EXPORT_SYMBOL_GPL(tty_buffer_lock_exclusive); |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 86 | |
| 87 | void tty_buffer_unlock_exclusive(struct tty_port *port) |
| 88 | { |
| 89 | struct tty_bufhead *buf = &port->buf; |
| 90 | int restart; |
| 91 | |
| 92 | restart = buf->head->commit != buf->head->read; |
| 93 | |
| 94 | atomic_dec(&buf->priority); |
| 95 | mutex_unlock(&buf->lock); |
| 96 | if (restart) |
| 97 | queue_work(system_unbound_wq, &buf->work); |
| 98 | } |
Ben Hutchings | 28a821c | 2014-05-19 01:03:06 +0100 | [diff] [blame] | 99 | EXPORT_SYMBOL_GPL(tty_buffer_unlock_exclusive); |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 100 | |
| 101 | /** |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 102 | * tty_buffer_space_avail - return unused buffer space |
| 103 | * @port - tty_port owning the flip buffer |
| 104 | * |
| 105 | * Returns the # of bytes which can be written by the driver without |
| 106 | * reaching the buffer limit. |
| 107 | * |
| 108 | * Note: this does not guarantee that memory is available to write |
| 109 | * the returned # of bytes (use tty_prepare_flip_string_xxx() to |
| 110 | * pre-allocate if memory guarantee is required). |
| 111 | */ |
| 112 | |
| 113 | int tty_buffer_space_avail(struct tty_port *port) |
| 114 | { |
Peter Hurley | 5dda4ca | 2013-11-22 12:09:56 -0500 | [diff] [blame] | 115 | int space = port->buf.mem_limit - atomic_read(&port->buf.mem_used); |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 116 | return max(space, 0); |
| 117 | } |
Peter Hurley | c4a8dab | 2013-11-22 13:06:08 -0500 | [diff] [blame] | 118 | EXPORT_SYMBOL_GPL(tty_buffer_space_avail); |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 119 | |
Peter Hurley | 9dd5139 | 2013-06-15 09:36:03 -0400 | [diff] [blame] | 120 | static void tty_buffer_reset(struct tty_buffer *p, size_t size) |
| 121 | { |
| 122 | p->used = 0; |
| 123 | p->size = size; |
| 124 | p->next = NULL; |
| 125 | p->commit = 0; |
| 126 | p->read = 0; |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 127 | p->flags = 0; |
Peter Hurley | 9dd5139 | 2013-06-15 09:36:03 -0400 | [diff] [blame] | 128 | } |
| 129 | |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 130 | /** |
| 131 | * tty_buffer_free_all - free buffers used by a tty |
| 132 | * @tty: tty to free from |
| 133 | * |
| 134 | * Remove all the buffers pending on a tty whether queued with data |
| 135 | * or in the free ring. Must be called when the tty is no longer in use |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 136 | */ |
| 137 | |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 138 | void tty_buffer_free_all(struct tty_port *port) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 139 | { |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 140 | struct tty_bufhead *buf = &port->buf; |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 141 | struct tty_buffer *p, *next; |
| 142 | struct llist_node *llist; |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 143 | |
Peter Hurley | 2cf7b67 | 2013-06-15 09:36:05 -0400 | [diff] [blame] | 144 | while ((p = buf->head) != NULL) { |
| 145 | buf->head = p->next; |
Peter Hurley | 7391ee1 | 2013-06-15 09:36:07 -0400 | [diff] [blame] | 146 | if (p->size > 0) |
| 147 | kfree(p); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 148 | } |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 149 | llist = llist_del_all(&buf->free); |
| 150 | llist_for_each_entry_safe(p, next, llist, free) |
Peter Hurley | 2cf7b67 | 2013-06-15 09:36:05 -0400 | [diff] [blame] | 151 | kfree(p); |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 152 | |
Peter Hurley | 7391ee1 | 2013-06-15 09:36:07 -0400 | [diff] [blame] | 153 | tty_buffer_reset(&buf->sentinel, 0); |
| 154 | buf->head = &buf->sentinel; |
| 155 | buf->tail = &buf->sentinel; |
Peter Hurley | 7bfe0b7 | 2013-06-15 09:36:08 -0400 | [diff] [blame] | 156 | |
Peter Hurley | 5dda4ca | 2013-11-22 12:09:56 -0500 | [diff] [blame] | 157 | atomic_set(&buf->mem_used, 0); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 158 | } |
| 159 | |
| 160 | /** |
| 161 | * tty_buffer_alloc - allocate a tty buffer |
| 162 | * @tty: tty device |
| 163 | * @size: desired size (characters) |
| 164 | * |
| 165 | * Allocate a new tty buffer to hold the desired number of characters. |
Peter Hurley | 11b9faa | 2013-06-15 09:36:04 -0400 | [diff] [blame] | 166 | * We round our buffers off in 256 character chunks to get better |
| 167 | * allocation behaviour. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 168 | * Return NULL if out of memory or the allocation would exceed the |
| 169 | * per device queue |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 170 | */ |
| 171 | |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 172 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 173 | { |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 174 | struct llist_node *free; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 175 | struct tty_buffer *p; |
| 176 | |
Peter Hurley | 11b9faa | 2013-06-15 09:36:04 -0400 | [diff] [blame] | 177 | /* Round the buffer size out */ |
| 178 | size = __ALIGN_MASK(size, TTYB_ALIGN_MASK); |
| 179 | |
| 180 | if (size <= MIN_TTYB_SIZE) { |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 181 | free = llist_del_first(&port->buf.free); |
| 182 | if (free) { |
| 183 | p = llist_entry(free, struct tty_buffer, free); |
Peter Hurley | 11b9faa | 2013-06-15 09:36:04 -0400 | [diff] [blame] | 184 | goto found; |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | /* Should possibly check if this fails for the largest buffer we |
| 189 | have queued and recycle that ? */ |
Peter Hurley | 5dda4ca | 2013-11-22 12:09:56 -0500 | [diff] [blame] | 190 | if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 191 | return NULL; |
| 192 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); |
| 193 | if (p == NULL) |
| 194 | return NULL; |
Peter Hurley | 9dd5139 | 2013-06-15 09:36:03 -0400 | [diff] [blame] | 195 | |
Peter Hurley | 11b9faa | 2013-06-15 09:36:04 -0400 | [diff] [blame] | 196 | found: |
Peter Hurley | 9dd5139 | 2013-06-15 09:36:03 -0400 | [diff] [blame] | 197 | tty_buffer_reset(p, size); |
Peter Hurley | 5dda4ca | 2013-11-22 12:09:56 -0500 | [diff] [blame] | 198 | atomic_add(size, &port->buf.mem_used); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 199 | return p; |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * tty_buffer_free - free a tty buffer |
| 204 | * @tty: tty owning the buffer |
| 205 | * @b: the buffer to free |
| 206 | * |
| 207 | * Free a tty buffer, or add it to the free list according to our |
| 208 | * internal strategy |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 209 | */ |
| 210 | |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 211 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 212 | { |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 213 | struct tty_bufhead *buf = &port->buf; |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 214 | |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 215 | /* Dumb strategy for now - should keep some stats */ |
Peter Hurley | 5dda4ca | 2013-11-22 12:09:56 -0500 | [diff] [blame] | 216 | WARN_ON(atomic_sub_return(b->size, &buf->mem_used) < 0); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 217 | |
Peter Hurley | 1cef50e | 2013-06-15 09:36:02 -0400 | [diff] [blame] | 218 | if (b->size > MIN_TTYB_SIZE) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 219 | kfree(b); |
Peter Hurley | 7391ee1 | 2013-06-15 09:36:07 -0400 | [diff] [blame] | 220 | else if (b->size > 0) |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 221 | llist_add(&b->free, &buf->free); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 222 | } |
| 223 | |
| 224 | /** |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 225 | * tty_buffer_flush - flush full tty buffers |
| 226 | * @tty: tty to flush |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 227 | * @ld: optional ldisc ptr (must be referenced) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 228 | * |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 229 | * flush all the buffers containing receive data. If ld != NULL, |
| 230 | * flush the ldisc input buffer. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 231 | * |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 232 | * Locking: takes buffer lock to ensure single-threaded flip buffer |
Peter Hurley | e9975fd | 2013-06-15 09:36:10 -0400 | [diff] [blame] | 233 | * 'consumer' |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 234 | */ |
| 235 | |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 236 | void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 237 | { |
Jiri Slaby | 2fc2066 | 2012-10-18 22:26:44 +0200 | [diff] [blame] | 238 | struct tty_port *port = tty->port; |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 239 | struct tty_bufhead *buf = &port->buf; |
Peter Hurley | 47aa658 | 2013-06-15 09:36:14 -0400 | [diff] [blame] | 240 | struct tty_buffer *next; |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 241 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 242 | atomic_inc(&buf->priority); |
Peter Hurley | e9975fd | 2013-06-15 09:36:10 -0400 | [diff] [blame] | 243 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 244 | mutex_lock(&buf->lock); |
Dmitry Vyukov | 9e6b7cd | 2015-09-17 17:17:09 +0200 | [diff] [blame] | 245 | /* paired w/ release in __tty_buffer_request_room; ensures there are |
| 246 | * no pending memory accesses to the freed buffer |
| 247 | */ |
| 248 | while ((next = smp_load_acquire(&buf->head->next)) != NULL) { |
Peter Hurley | 47aa658 | 2013-06-15 09:36:14 -0400 | [diff] [blame] | 249 | tty_buffer_free(port, buf->head); |
| 250 | buf->head = next; |
| 251 | } |
| 252 | buf->head->read = buf->head->commit; |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 253 | |
| 254 | if (ld && ld->ops->flush_buffer) |
| 255 | ld->ops->flush_buffer(tty); |
| 256 | |
Peter Hurley | 1a48632 | 2015-04-13 13:24:34 -0400 | [diff] [blame] | 257 | check_other_closed(tty); |
| 258 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 259 | atomic_dec(&buf->priority); |
| 260 | mutex_unlock(&buf->lock); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 261 | } |
| 262 | |
| 263 | /** |
Ilya Zykov | 64325a3 | 2013-01-19 18:16:20 +0400 | [diff] [blame] | 264 | * tty_buffer_request_room - grow tty buffer if needed |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 265 | * @tty: tty structure |
| 266 | * @size: size desired |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 267 | * @flags: buffer flags if new buffer allocated (default = 0) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 268 | * |
| 269 | * Make at least size bytes of linear space available for the tty |
| 270 | * buffer. If we fail return the size we managed to find. |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 271 | * |
| 272 | * Will change over to a new buffer if the current buffer is encoded as |
| 273 | * TTY_NORMAL (so has no flags buffer) and the new buffer requires |
| 274 | * a flags buffer. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 275 | */ |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 276 | static int __tty_buffer_request_room(struct tty_port *port, size_t size, |
| 277 | int flags) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 278 | { |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 279 | struct tty_bufhead *buf = &port->buf; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 280 | struct tty_buffer *b, *n; |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 281 | int left, change; |
Peter Hurley | e8437d7 | 2013-06-15 09:36:09 -0400 | [diff] [blame] | 282 | |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 283 | b = buf->tail; |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 284 | if (b->flags & TTYB_NORMAL) |
| 285 | left = 2 * b->size - b->used; |
| 286 | else |
| 287 | left = b->size - b->used; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 288 | |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 289 | change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL); |
| 290 | if (change || left < size) { |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 291 | /* This is the slow path - looking for new buffers to use */ |
Greg Kroah-Hartman | e16cb0a | 2015-04-30 11:22:17 +0200 | [diff] [blame] | 292 | n = tty_buffer_alloc(port, size); |
| 293 | if (n != NULL) { |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 294 | n->flags = flags; |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 295 | buf->tail = n; |
Dmitry Vyukov | facd885 | 2015-09-17 17:17:10 +0200 | [diff] [blame] | 296 | /* paired w/ acquire in flush_to_ldisc(); ensures |
| 297 | * flush_to_ldisc() sees buffer data. |
| 298 | */ |
| 299 | smp_store_release(&b->commit, b->used); |
Peter Hurley | 069f38b | 2015-07-12 20:50:49 -0400 | [diff] [blame] | 300 | /* paired w/ acquire in flush_to_ldisc(); ensures the |
Peter Hurley | 62a0d8d | 2014-05-02 10:56:12 -0400 | [diff] [blame] | 301 | * latest commit value can be read before the head is |
| 302 | * advanced to the next buffer |
| 303 | */ |
Peter Hurley | 069f38b | 2015-07-12 20:50:49 -0400 | [diff] [blame] | 304 | smp_store_release(&b->next, n); |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 305 | } else if (change) |
| 306 | size = 0; |
| 307 | else |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 308 | size = left; |
| 309 | } |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 310 | return size; |
| 311 | } |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 312 | |
| 313 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
| 314 | { |
| 315 | return __tty_buffer_request_room(port, size, 0); |
| 316 | } |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 317 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); |
| 318 | |
| 319 | /** |
Alan Cox | 2832fc1 | 2010-02-18 16:43:54 +0000 | [diff] [blame] | 320 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
Jiri Slaby | 2f69335 | 2013-01-03 15:53:02 +0100 | [diff] [blame] | 321 | * @port: tty port |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 322 | * @chars: characters |
Alan Cox | 2832fc1 | 2010-02-18 16:43:54 +0000 | [diff] [blame] | 323 | * @flag: flag value for each character |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 324 | * @size: size |
| 325 | * |
| 326 | * Queue a series of bytes to the tty buffering. All the characters |
Johan Hovold | ccc5ca8 | 2010-05-07 19:58:32 +0200 | [diff] [blame] | 327 | * passed are marked with the supplied flag. Returns the number added. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 328 | */ |
| 329 | |
Jiri Slaby | 2f69335 | 2013-01-03 15:53:02 +0100 | [diff] [blame] | 330 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
Alan Cox | 2832fc1 | 2010-02-18 16:43:54 +0000 | [diff] [blame] | 331 | const unsigned char *chars, char flag, size_t size) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 332 | { |
| 333 | int copied = 0; |
| 334 | do { |
Fang Wenqi | d4bee0a | 2010-03-09 18:54:28 +0800 | [diff] [blame] | 335 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 336 | int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0; |
| 337 | int space = __tty_buffer_request_room(port, goal, flags); |
Ilya Zykov | 64325a3 | 2013-01-19 18:16:20 +0400 | [diff] [blame] | 338 | struct tty_buffer *tb = port->buf.tail; |
Peter Hurley | 7391ee1 | 2013-06-15 09:36:07 -0400 | [diff] [blame] | 339 | if (unlikely(space == 0)) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 340 | break; |
Peter Hurley | 1fc359f | 2013-06-15 09:36:01 -0400 | [diff] [blame] | 341 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 342 | if (~tb->flags & TTYB_NORMAL) |
| 343 | memset(flag_buf_ptr(tb, tb->used), flag, space); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 344 | tb->used += space; |
| 345 | copied += space; |
| 346 | chars += space; |
| 347 | /* There is a small chance that we need to split the data over |
| 348 | several buffers. If this is the case we must loop */ |
| 349 | } while (unlikely(size > copied)); |
| 350 | return copied; |
| 351 | } |
Alan Cox | 2832fc1 | 2010-02-18 16:43:54 +0000 | [diff] [blame] | 352 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 353 | |
| 354 | /** |
| 355 | * tty_insert_flip_string_flags - Add characters to the tty buffer |
Jiri Slaby | 2f69335 | 2013-01-03 15:53:02 +0100 | [diff] [blame] | 356 | * @port: tty port |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 357 | * @chars: characters |
| 358 | * @flags: flag bytes |
| 359 | * @size: size |
| 360 | * |
| 361 | * Queue a series of bytes to the tty buffering. For each character |
| 362 | * the flags array indicates the status of the character. Returns the |
| 363 | * number added. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 364 | */ |
| 365 | |
Jiri Slaby | 2f69335 | 2013-01-03 15:53:02 +0100 | [diff] [blame] | 366 | int tty_insert_flip_string_flags(struct tty_port *port, |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 367 | const unsigned char *chars, const char *flags, size_t size) |
| 368 | { |
| 369 | int copied = 0; |
| 370 | do { |
Fang Wenqi | d4bee0a | 2010-03-09 18:54:28 +0800 | [diff] [blame] | 371 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
Ilya Zykov | 64325a3 | 2013-01-19 18:16:20 +0400 | [diff] [blame] | 372 | int space = tty_buffer_request_room(port, goal); |
| 373 | struct tty_buffer *tb = port->buf.tail; |
Peter Hurley | 7391ee1 | 2013-06-15 09:36:07 -0400 | [diff] [blame] | 374 | if (unlikely(space == 0)) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 375 | break; |
Peter Hurley | 1fc359f | 2013-06-15 09:36:01 -0400 | [diff] [blame] | 376 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
| 377 | memcpy(flag_buf_ptr(tb, tb->used), flags, space); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 378 | tb->used += space; |
| 379 | copied += space; |
| 380 | chars += space; |
| 381 | flags += space; |
| 382 | /* There is a small chance that we need to split the data over |
| 383 | several buffers. If this is the case we must loop */ |
| 384 | } while (unlikely(size > copied)); |
| 385 | return copied; |
| 386 | } |
| 387 | EXPORT_SYMBOL(tty_insert_flip_string_flags); |
| 388 | |
| 389 | /** |
| 390 | * tty_schedule_flip - push characters to ldisc |
Jiri Slaby | 6732c8b | 2013-01-03 15:53:07 +0100 | [diff] [blame] | 391 | * @port: tty port to push from |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 392 | * |
| 393 | * Takes any pending buffers and transfers their ownership to the |
| 394 | * ldisc side of the queue. It then schedules those characters for |
| 395 | * processing by the line discipline. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 396 | */ |
| 397 | |
Jiri Slaby | 6732c8b | 2013-01-03 15:53:07 +0100 | [diff] [blame] | 398 | void tty_schedule_flip(struct tty_port *port) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 399 | { |
Jiri Slaby | 6732c8b | 2013-01-03 15:53:07 +0100 | [diff] [blame] | 400 | struct tty_bufhead *buf = &port->buf; |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 401 | |
Dmitry Vyukov | facd885 | 2015-09-17 17:17:10 +0200 | [diff] [blame] | 402 | /* paired w/ acquire in flush_to_ldisc(); ensures |
| 403 | * flush_to_ldisc() sees buffer data. |
| 404 | */ |
| 405 | smp_store_release(&buf->tail->commit, buf->tail->used); |
Peter Hurley | e052c6d | 2015-10-17 16:36:24 -0400 | [diff] [blame] | 406 | queue_work(system_unbound_wq, &buf->work); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 407 | } |
| 408 | EXPORT_SYMBOL(tty_schedule_flip); |
| 409 | |
| 410 | /** |
| 411 | * tty_prepare_flip_string - make room for characters |
Jiri Slaby | 2f69335 | 2013-01-03 15:53:02 +0100 | [diff] [blame] | 412 | * @port: tty port |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 413 | * @chars: return pointer for character write area |
| 414 | * @size: desired size |
| 415 | * |
| 416 | * Prepare a block of space in the buffer for data. Returns the length |
| 417 | * available and buffer pointer to the space which is now allocated and |
| 418 | * accounted for as ready for normal characters. This is used for drivers |
| 419 | * that need their own block copy routines into the buffer. There is no |
| 420 | * guarantee the buffer is a DMA target! |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 421 | */ |
| 422 | |
Jiri Slaby | 2f69335 | 2013-01-03 15:53:02 +0100 | [diff] [blame] | 423 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 424 | size_t size) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 425 | { |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 426 | int space = __tty_buffer_request_room(port, size, TTYB_NORMAL); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 427 | if (likely(space)) { |
Ilya Zykov | 64325a3 | 2013-01-19 18:16:20 +0400 | [diff] [blame] | 428 | struct tty_buffer *tb = port->buf.tail; |
Peter Hurley | 1fc359f | 2013-06-15 09:36:01 -0400 | [diff] [blame] | 429 | *chars = char_buf_ptr(tb, tb->used); |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 430 | if (~tb->flags & TTYB_NORMAL) |
| 431 | memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 432 | tb->used += space; |
| 433 | } |
| 434 | return space; |
| 435 | } |
| 436 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); |
| 437 | |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 438 | |
Peter Hurley | da261e7 | 2013-06-15 09:14:14 -0400 | [diff] [blame] | 439 | static int |
| 440 | receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) |
| 441 | { |
| 442 | struct tty_ldisc *disc = tty->ldisc; |
Peter Hurley | 1fc359f | 2013-06-15 09:36:01 -0400 | [diff] [blame] | 443 | unsigned char *p = char_buf_ptr(head, head->read); |
Peter Hurley | acc0f67 | 2013-12-09 09:23:52 -0500 | [diff] [blame] | 444 | char *f = NULL; |
| 445 | |
| 446 | if (~head->flags & TTYB_NORMAL) |
| 447 | f = flag_buf_ptr(head, head->read); |
Peter Hurley | da261e7 | 2013-06-15 09:14:14 -0400 | [diff] [blame] | 448 | |
Peter Hurley | 24a89d1 | 2013-06-15 09:14:15 -0400 | [diff] [blame] | 449 | if (disc->ops->receive_buf2) |
| 450 | count = disc->ops->receive_buf2(tty, p, f, count); |
| 451 | else { |
| 452 | count = min_t(int, count, tty->receive_room); |
| 453 | if (count) |
| 454 | disc->ops->receive_buf(tty, p, f, count); |
| 455 | } |
Peter Hurley | da261e7 | 2013-06-15 09:14:14 -0400 | [diff] [blame] | 456 | return count; |
| 457 | } |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 458 | |
| 459 | /** |
| 460 | * flush_to_ldisc |
| 461 | * @work: tty structure passed from work queue. |
| 462 | * |
| 463 | * This routine is called out of the software interrupt to flush data |
| 464 | * from the buffer chain to the line discipline. |
| 465 | * |
Peter Hurley | e9975fd | 2013-06-15 09:36:10 -0400 | [diff] [blame] | 466 | * The receive_buf method is single threaded for each tty instance. |
| 467 | * |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 468 | * Locking: takes buffer lock to ensure single-threaded flip buffer |
Peter Hurley | e9975fd | 2013-06-15 09:36:10 -0400 | [diff] [blame] | 469 | * 'consumer' |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 470 | */ |
| 471 | |
| 472 | static void flush_to_ldisc(struct work_struct *work) |
| 473 | { |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 474 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
| 475 | struct tty_bufhead *buf = &port->buf; |
| 476 | struct tty_struct *tty; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 477 | struct tty_ldisc *disc; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 478 | |
Dmitry Vyukov | 7098296 | 2015-09-17 17:17:08 +0200 | [diff] [blame] | 479 | tty = READ_ONCE(port->itty); |
Jiri Slaby | 34dcfb8 | 2013-02-27 22:30:24 +0100 | [diff] [blame] | 480 | if (tty == NULL) |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 481 | return; |
| 482 | |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 483 | disc = tty_ldisc_ref(tty); |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 484 | if (disc == NULL) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 485 | return; |
| 486 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 487 | mutex_lock(&buf->lock); |
Linus Torvalds | 4524200 | 2009-10-14 08:59:49 -0700 | [diff] [blame] | 488 | |
Peter Hurley | d7a68be | 2013-06-15 09:36:11 -0400 | [diff] [blame] | 489 | while (1) { |
| 490 | struct tty_buffer *head = buf->head; |
Peter Hurley | 62a0d8d | 2014-05-02 10:56:12 -0400 | [diff] [blame] | 491 | struct tty_buffer *next; |
Peter Hurley | d7a68be | 2013-06-15 09:36:11 -0400 | [diff] [blame] | 492 | int count; |
Linus Torvalds | 4524200 | 2009-10-14 08:59:49 -0700 | [diff] [blame] | 493 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 494 | /* Ldisc or user is trying to gain exclusive access */ |
| 495 | if (atomic_read(&buf->priority)) |
Peter Hurley | d7a68be | 2013-06-15 09:36:11 -0400 | [diff] [blame] | 496 | break; |
Peter Hurley | e9975fd | 2013-06-15 09:36:10 -0400 | [diff] [blame] | 497 | |
Peter Hurley | 069f38b | 2015-07-12 20:50:49 -0400 | [diff] [blame] | 498 | /* paired w/ release in __tty_buffer_request_room(); |
Peter Hurley | 62a0d8d | 2014-05-02 10:56:12 -0400 | [diff] [blame] | 499 | * ensures commit value read is not stale if the head |
| 500 | * is advancing to the next buffer |
| 501 | */ |
Peter Hurley | 069f38b | 2015-07-12 20:50:49 -0400 | [diff] [blame] | 502 | next = smp_load_acquire(&head->next); |
Dmitry Vyukov | facd885 | 2015-09-17 17:17:10 +0200 | [diff] [blame] | 503 | /* paired w/ release in __tty_buffer_request_room() or in |
| 504 | * tty_buffer_flush(); ensures we see the committed buffer data |
| 505 | */ |
| 506 | count = smp_load_acquire(&head->commit) - head->read; |
Peter Hurley | d7a68be | 2013-06-15 09:36:11 -0400 | [diff] [blame] | 507 | if (!count) { |
Peter Hurley | 1a48632 | 2015-04-13 13:24:34 -0400 | [diff] [blame] | 508 | if (next == NULL) { |
| 509 | check_other_closed(tty); |
Peter Hurley | 39f610e | 2013-03-20 13:20:43 -0400 | [diff] [blame] | 510 | break; |
Peter Hurley | 1a48632 | 2015-04-13 13:24:34 -0400 | [diff] [blame] | 511 | } |
Peter Hurley | 62a0d8d | 2014-05-02 10:56:12 -0400 | [diff] [blame] | 512 | buf->head = next; |
Peter Hurley | d7a68be | 2013-06-15 09:36:11 -0400 | [diff] [blame] | 513 | tty_buffer_free(port, head); |
| 514 | continue; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 515 | } |
Peter Hurley | d7a68be | 2013-06-15 09:36:11 -0400 | [diff] [blame] | 516 | |
| 517 | count = receive_buf(tty, head, count); |
| 518 | if (!count) |
| 519 | break; |
Peter Hurley | af5554f | 2015-07-12 20:50:50 -0400 | [diff] [blame] | 520 | head->read += count; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 521 | } |
Linus Torvalds | 4524200 | 2009-10-14 08:59:49 -0700 | [diff] [blame] | 522 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 523 | mutex_unlock(&buf->lock); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 524 | |
| 525 | tty_ldisc_deref(disc); |
| 526 | } |
| 527 | |
| 528 | /** |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 529 | * tty_flip_buffer_push - terminal |
Jiri Slaby | 2e124b4 | 2013-01-03 15:53:06 +0100 | [diff] [blame] | 530 | * @port: tty port to push |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 531 | * |
Peter Hurley | a9c3f68 | 2014-02-22 07:31:21 -0500 | [diff] [blame] | 532 | * Queue a push of the terminal flip buffers to the line discipline. |
| 533 | * Can be called from IRQ/atomic context. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 534 | * |
| 535 | * In the event of the queue being busy for flipping the work will be |
| 536 | * held off and retried later. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 537 | */ |
| 538 | |
Jiri Slaby | 2e124b4 | 2013-01-03 15:53:06 +0100 | [diff] [blame] | 539 | void tty_flip_buffer_push(struct tty_port *port) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 540 | { |
Peter Hurley | a9c3f68 | 2014-02-22 07:31:21 -0500 | [diff] [blame] | 541 | tty_schedule_flip(port); |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 542 | } |
| 543 | EXPORT_SYMBOL(tty_flip_buffer_push); |
| 544 | |
| 545 | /** |
| 546 | * tty_buffer_init - prepare a tty buffer structure |
| 547 | * @tty: tty to initialise |
| 548 | * |
| 549 | * Set up the initial state of the buffer management for a tty device. |
| 550 | * Must be called before the other tty buffer functions are used. |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 551 | */ |
| 552 | |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 553 | void tty_buffer_init(struct tty_port *port) |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 554 | { |
Jiri Slaby | ecbbfd4 | 2012-10-18 22:26:47 +0200 | [diff] [blame] | 555 | struct tty_bufhead *buf = &port->buf; |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 556 | |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 557 | mutex_init(&buf->lock); |
Peter Hurley | 7391ee1 | 2013-06-15 09:36:07 -0400 | [diff] [blame] | 558 | tty_buffer_reset(&buf->sentinel, 0); |
| 559 | buf->head = &buf->sentinel; |
| 560 | buf->tail = &buf->sentinel; |
Peter Hurley | 809850b | 2013-06-15 09:36:06 -0400 | [diff] [blame] | 561 | init_llist_head(&buf->free); |
Peter Hurley | 5dda4ca | 2013-11-22 12:09:56 -0500 | [diff] [blame] | 562 | atomic_set(&buf->mem_used, 0); |
Peter Hurley | a7c8d58 | 2013-06-15 09:36:15 -0400 | [diff] [blame] | 563 | atomic_set(&buf->priority, 0); |
Jiri Slaby | 5cff39c | 2012-10-18 22:26:45 +0200 | [diff] [blame] | 564 | INIT_WORK(&buf->work, flush_to_ldisc); |
Peter Hurley | 4d18e6ef | 2013-11-22 12:09:55 -0500 | [diff] [blame] | 565 | buf->mem_limit = TTYB_DEFAULT_MEM_LIMIT; |
Alan Cox | e049573 | 2008-10-13 10:36:58 +0100 | [diff] [blame] | 566 | } |
Peter Hurley | 4d18e6ef | 2013-11-22 12:09:55 -0500 | [diff] [blame] | 567 | |
| 568 | /** |
| 569 | * tty_buffer_set_limit - change the tty buffer memory limit |
| 570 | * @port: tty port to change |
| 571 | * |
| 572 | * Change the tty buffer memory limit. |
| 573 | * Must be called before the other tty buffer functions are used. |
| 574 | */ |
| 575 | |
| 576 | int tty_buffer_set_limit(struct tty_port *port, int limit) |
| 577 | { |
| 578 | if (limit < MIN_TTYB_SIZE) |
| 579 | return -EINVAL; |
| 580 | port->buf.mem_limit = limit; |
| 581 | return 0; |
| 582 | } |
| 583 | EXPORT_SYMBOL_GPL(tty_buffer_set_limit); |
Peter Hurley | 1d1d14d | 2015-01-17 15:42:05 -0500 | [diff] [blame] | 584 | |
| 585 | /* slave ptys can claim nested buffer lock when handling BRK and INTR */ |
| 586 | void tty_buffer_set_lock_subclass(struct tty_port *port) |
| 587 | { |
| 588 | lockdep_set_subclass(&port->buf.lock, TTY_LOCK_SLAVE); |
| 589 | } |
Peter Hurley | e176058 | 2015-10-17 16:36:23 -0400 | [diff] [blame] | 590 | |
| 591 | bool tty_buffer_restart_work(struct tty_port *port) |
| 592 | { |
| 593 | return queue_work(system_unbound_wq, &port->buf.work); |
| 594 | } |
| 595 | |
| 596 | bool tty_buffer_cancel_work(struct tty_port *port) |
| 597 | { |
| 598 | return cancel_work_sync(&port->buf.work); |
| 599 | } |