Commit | Line | Data |
---|---|---|
e0495736 AC |
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> | |
e0495736 AC |
14 | #include <linux/wait.h> |
15 | #include <linux/bitops.h> | |
16 | #include <linux/delay.h> | |
17 | #include <linux/module.h> | |
593fb1ae | 18 | #include <linux/ratelimit.h> |
e0495736 | 19 | |
1cef50e3 PH |
20 | |
21 | #define MIN_TTYB_SIZE 256 | |
22 | #define TTYB_ALIGN_MASK 255 | |
23 | ||
7bfe0b71 PH |
24 | /* |
25 | * Byte threshold to limit memory consumption for flip buffers. | |
26 | * The actual memory limit is > 2x this amount. | |
27 | */ | |
4d18e6ef | 28 | #define TTYB_DEFAULT_MEM_LIMIT 65536 |
7bfe0b71 | 29 | |
9114fe8c PH |
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 | ||
1a48632f PH |
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 | } | |
7bfe0b71 | 62 | |
a7c8d58c PH |
63 | /** |
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 | } | |
28a821c3 | 85 | EXPORT_SYMBOL_GPL(tty_buffer_lock_exclusive); |
a7c8d58c PH |
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 | } | |
28a821c3 | 99 | EXPORT_SYMBOL_GPL(tty_buffer_unlock_exclusive); |
a7c8d58c | 100 | |
7bfe0b71 PH |
101 | /** |
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 | { | |
5dda4ca5 | 115 | int space = port->buf.mem_limit - atomic_read(&port->buf.mem_used); |
7bfe0b71 PH |
116 | return max(space, 0); |
117 | } | |
c4a8dab5 | 118 | EXPORT_SYMBOL_GPL(tty_buffer_space_avail); |
7bfe0b71 | 119 | |
9dd5139f PH |
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; | |
acc0f67f | 127 | p->flags = 0; |
9dd5139f PH |
128 | } |
129 | ||
e0495736 AC |
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 | |
e0495736 AC |
136 | */ |
137 | ||
ecbbfd44 | 138 | void tty_buffer_free_all(struct tty_port *port) |
e0495736 | 139 | { |
ecbbfd44 | 140 | struct tty_bufhead *buf = &port->buf; |
809850b7 PH |
141 | struct tty_buffer *p, *next; |
142 | struct llist_node *llist; | |
5cff39c6 | 143 | |
2cf7b67e PH |
144 | while ((p = buf->head) != NULL) { |
145 | buf->head = p->next; | |
7391ee16 PH |
146 | if (p->size > 0) |
147 | kfree(p); | |
e0495736 | 148 | } |
809850b7 PH |
149 | llist = llist_del_all(&buf->free); |
150 | llist_for_each_entry_safe(p, next, llist, free) | |
2cf7b67e | 151 | kfree(p); |
809850b7 | 152 | |
7391ee16 PH |
153 | tty_buffer_reset(&buf->sentinel, 0); |
154 | buf->head = &buf->sentinel; | |
155 | buf->tail = &buf->sentinel; | |
7bfe0b71 | 156 | |
5dda4ca5 | 157 | atomic_set(&buf->mem_used, 0); |
e0495736 AC |
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. | |
11b9faa4 PH |
166 | * We round our buffers off in 256 character chunks to get better |
167 | * allocation behaviour. | |
e0495736 AC |
168 | * Return NULL if out of memory or the allocation would exceed the |
169 | * per device queue | |
e0495736 AC |
170 | */ |
171 | ||
ecbbfd44 | 172 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
e0495736 | 173 | { |
809850b7 | 174 | struct llist_node *free; |
e0495736 AC |
175 | struct tty_buffer *p; |
176 | ||
11b9faa4 PH |
177 | /* Round the buffer size out */ |
178 | size = __ALIGN_MASK(size, TTYB_ALIGN_MASK); | |
179 | ||
180 | if (size <= MIN_TTYB_SIZE) { | |
809850b7 PH |
181 | free = llist_del_first(&port->buf.free); |
182 | if (free) { | |
183 | p = llist_entry(free, struct tty_buffer, free); | |
11b9faa4 PH |
184 | goto found; |
185 | } | |
186 | } | |
187 | ||
188 | /* Should possibly check if this fails for the largest buffer we | |
189 | have queued and recycle that ? */ | |
5dda4ca5 | 190 | if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit) |
e0495736 AC |
191 | return NULL; |
192 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); | |
193 | if (p == NULL) | |
194 | return NULL; | |
9dd5139f | 195 | |
11b9faa4 | 196 | found: |
9dd5139f | 197 | tty_buffer_reset(p, size); |
5dda4ca5 | 198 | atomic_add(size, &port->buf.mem_used); |
e0495736 AC |
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 | |
e0495736 AC |
209 | */ |
210 | ||
ecbbfd44 | 211 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 212 | { |
ecbbfd44 | 213 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 214 | |
e0495736 | 215 | /* Dumb strategy for now - should keep some stats */ |
5dda4ca5 | 216 | WARN_ON(atomic_sub_return(b->size, &buf->mem_used) < 0); |
e0495736 | 217 | |
1cef50e3 | 218 | if (b->size > MIN_TTYB_SIZE) |
e0495736 | 219 | kfree(b); |
7391ee16 | 220 | else if (b->size > 0) |
809850b7 | 221 | llist_add(&b->free, &buf->free); |
e0495736 AC |
222 | } |
223 | ||
e0495736 AC |
224 | /** |
225 | * tty_buffer_flush - flush full tty buffers | |
226 | * @tty: tty to flush | |
86c80a8e | 227 | * @ld: optional ldisc ptr (must be referenced) |
e0495736 | 228 | * |
86c80a8e PH |
229 | * flush all the buffers containing receive data. If ld != NULL, |
230 | * flush the ldisc input buffer. | |
e0495736 | 231 | * |
a7c8d58c | 232 | * Locking: takes buffer lock to ensure single-threaded flip buffer |
e9975fde | 233 | * 'consumer' |
e0495736 AC |
234 | */ |
235 | ||
86c80a8e | 236 | void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld) |
e0495736 | 237 | { |
2fc20661 | 238 | struct tty_port *port = tty->port; |
ecbbfd44 | 239 | struct tty_bufhead *buf = &port->buf; |
47aa658a | 240 | struct tty_buffer *next; |
e0495736 | 241 | |
a7c8d58c | 242 | atomic_inc(&buf->priority); |
e9975fde | 243 | |
a7c8d58c | 244 | mutex_lock(&buf->lock); |
9e6b7cd7 DV |
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) { | |
47aa658a PH |
249 | tty_buffer_free(port, buf->head); |
250 | buf->head = next; | |
251 | } | |
252 | buf->head->read = buf->head->commit; | |
86c80a8e PH |
253 | |
254 | if (ld && ld->ops->flush_buffer) | |
255 | ld->ops->flush_buffer(tty); | |
256 | ||
1a48632f PH |
257 | check_other_closed(tty); |
258 | ||
a7c8d58c PH |
259 | atomic_dec(&buf->priority); |
260 | mutex_unlock(&buf->lock); | |
e0495736 AC |
261 | } |
262 | ||
e0495736 | 263 | /** |
64325a3b | 264 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
265 | * @tty: tty structure |
266 | * @size: size desired | |
acc0f67f | 267 | * @flags: buffer flags if new buffer allocated (default = 0) |
e0495736 AC |
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. | |
acc0f67f PH |
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. | |
e0495736 | 275 | */ |
acc0f67f PH |
276 | static int __tty_buffer_request_room(struct tty_port *port, size_t size, |
277 | int flags) | |
e0495736 | 278 | { |
ecbbfd44 | 279 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 280 | struct tty_buffer *b, *n; |
acc0f67f | 281 | int left, change; |
e8437d7e | 282 | |
5cff39c6 | 283 | b = buf->tail; |
acc0f67f PH |
284 | if (b->flags & TTYB_NORMAL) |
285 | left = 2 * b->size - b->used; | |
286 | else | |
287 | left = b->size - b->used; | |
e0495736 | 288 | |
acc0f67f PH |
289 | change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL); |
290 | if (change || left < size) { | |
e0495736 | 291 | /* This is the slow path - looking for new buffers to use */ |
e16cb0a7 GKH |
292 | n = tty_buffer_alloc(port, size); |
293 | if (n != NULL) { | |
acc0f67f | 294 | n->flags = flags; |
5cff39c6 | 295 | buf->tail = n; |
facd885c DV |
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); | |
069f38b4 | 300 | /* paired w/ acquire in flush_to_ldisc(); ensures the |
62a0d8d7 PH |
301 | * latest commit value can be read before the head is |
302 | * advanced to the next buffer | |
303 | */ | |
069f38b4 | 304 | smp_store_release(&b->next, n); |
acc0f67f PH |
305 | } else if (change) |
306 | size = 0; | |
307 | else | |
e0495736 AC |
308 | size = left; |
309 | } | |
e0495736 AC |
310 | return size; |
311 | } | |
acc0f67f PH |
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 | } | |
e0495736 AC |
317 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); |
318 | ||
319 | /** | |
2832fc11 | 320 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 321 | * @port: tty port |
e0495736 | 322 | * @chars: characters |
2832fc11 | 323 | * @flag: flag value for each character |
e0495736 AC |
324 | * @size: size |
325 | * | |
326 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 327 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 AC |
328 | */ |
329 | ||
2f693357 | 330 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 331 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
332 | { |
333 | int copied = 0; | |
334 | do { | |
d4bee0a6 | 335 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
acc0f67f PH |
336 | int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0; |
337 | int space = __tty_buffer_request_room(port, goal, flags); | |
64325a3b | 338 | struct tty_buffer *tb = port->buf.tail; |
7391ee16 | 339 | if (unlikely(space == 0)) |
e0495736 | 340 | break; |
1fc359fc | 341 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
acc0f67f PH |
342 | if (~tb->flags & TTYB_NORMAL) |
343 | memset(flag_buf_ptr(tb, tb->used), flag, space); | |
e0495736 AC |
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 | } | |
2832fc11 | 352 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
353 | |
354 | /** | |
355 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 356 | * @port: tty port |
e0495736 AC |
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. | |
e0495736 AC |
364 | */ |
365 | ||
2f693357 | 366 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
367 | const unsigned char *chars, const char *flags, size_t size) |
368 | { | |
369 | int copied = 0; | |
370 | do { | |
d4bee0a6 | 371 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
372 | int space = tty_buffer_request_room(port, goal); |
373 | struct tty_buffer *tb = port->buf.tail; | |
7391ee16 | 374 | if (unlikely(space == 0)) |
e0495736 | 375 | break; |
1fc359fc PH |
376 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
377 | memcpy(flag_buf_ptr(tb, tb->used), flags, space); | |
e0495736 AC |
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 | |
6732c8bb | 391 | * @port: tty port to push from |
e0495736 AC |
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. | |
e0495736 AC |
396 | */ |
397 | ||
6732c8bb | 398 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 399 | { |
6732c8bb | 400 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 401 | |
facd885c DV |
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); | |
e052c6d1 | 406 | queue_work(system_unbound_wq, &buf->work); |
e0495736 AC |
407 | } |
408 | EXPORT_SYMBOL(tty_schedule_flip); | |
409 | ||
410 | /** | |
411 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 412 | * @port: tty port |
e0495736 AC |
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! | |
e0495736 AC |
421 | */ |
422 | ||
2f693357 | 423 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 424 | size_t size) |
e0495736 | 425 | { |
acc0f67f | 426 | int space = __tty_buffer_request_room(port, size, TTYB_NORMAL); |
e0495736 | 427 | if (likely(space)) { |
64325a3b | 428 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc | 429 | *chars = char_buf_ptr(tb, tb->used); |
acc0f67f PH |
430 | if (~tb->flags & TTYB_NORMAL) |
431 | memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space); | |
e0495736 AC |
432 | tb->used += space; |
433 | } | |
434 | return space; | |
435 | } | |
436 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
437 | ||
e0495736 | 438 | |
da261e7f PH |
439 | static int |
440 | receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) | |
441 | { | |
442 | struct tty_ldisc *disc = tty->ldisc; | |
1fc359fc | 443 | unsigned char *p = char_buf_ptr(head, head->read); |
acc0f67f PH |
444 | char *f = NULL; |
445 | ||
446 | if (~head->flags & TTYB_NORMAL) | |
447 | f = flag_buf_ptr(head, head->read); | |
da261e7f | 448 | |
24a89d1c PH |
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 | } | |
da261e7f PH |
456 | return count; |
457 | } | |
e0495736 AC |
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 | * | |
e9975fde PH |
466 | * The receive_buf method is single threaded for each tty instance. |
467 | * | |
a7c8d58c | 468 | * Locking: takes buffer lock to ensure single-threaded flip buffer |
e9975fde | 469 | * 'consumer' |
e0495736 AC |
470 | */ |
471 | ||
472 | static void flush_to_ldisc(struct work_struct *work) | |
473 | { | |
ecbbfd44 JS |
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; | |
e0495736 | 477 | struct tty_ldisc *disc; |
e0495736 | 478 | |
7098296a | 479 | tty = READ_ONCE(port->itty); |
34dcfb84 | 480 | if (tty == NULL) |
ecbbfd44 JS |
481 | return; |
482 | ||
e0495736 | 483 | disc = tty_ldisc_ref(tty); |
36697529 | 484 | if (disc == NULL) |
e0495736 AC |
485 | return; |
486 | ||
a7c8d58c | 487 | mutex_lock(&buf->lock); |
45242006 | 488 | |
d7a68be4 PH |
489 | while (1) { |
490 | struct tty_buffer *head = buf->head; | |
62a0d8d7 | 491 | struct tty_buffer *next; |
d7a68be4 PH |
492 | int count; |
493 | ||
a7c8d58c PH |
494 | /* Ldisc or user is trying to gain exclusive access */ |
495 | if (atomic_read(&buf->priority)) | |
d7a68be4 PH |
496 | break; |
497 | ||
069f38b4 | 498 | /* paired w/ release in __tty_buffer_request_room(); |
62a0d8d7 PH |
499 | * ensures commit value read is not stale if the head |
500 | * is advancing to the next buffer | |
501 | */ | |
069f38b4 | 502 | next = smp_load_acquire(&head->next); |
facd885c DV |
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; | |
d7a68be4 | 507 | if (!count) { |
1a48632f PH |
508 | if (next == NULL) { |
509 | check_other_closed(tty); | |
da261e7f | 510 | break; |
1a48632f | 511 | } |
62a0d8d7 | 512 | buf->head = next; |
d7a68be4 PH |
513 | tty_buffer_free(port, head); |
514 | continue; | |
e0495736 | 515 | } |
d7a68be4 PH |
516 | |
517 | count = receive_buf(tty, head, count); | |
518 | if (!count) | |
519 | break; | |
af5554f9 | 520 | head->read += count; |
e0495736 | 521 | } |
45242006 | 522 | |
a7c8d58c | 523 | mutex_unlock(&buf->lock); |
e0495736 AC |
524 | |
525 | tty_ldisc_deref(disc); | |
526 | } | |
527 | ||
528 | /** | |
529 | * tty_flip_buffer_push - terminal | |
2e124b4a | 530 | * @port: tty port to push |
e0495736 | 531 | * |
a9c3f68f PH |
532 | * Queue a push of the terminal flip buffers to the line discipline. |
533 | * Can be called from IRQ/atomic context. | |
e0495736 AC |
534 | * |
535 | * In the event of the queue being busy for flipping the work will be | |
536 | * held off and retried later. | |
e0495736 AC |
537 | */ |
538 | ||
2e124b4a | 539 | void tty_flip_buffer_push(struct tty_port *port) |
e0495736 | 540 | { |
a9c3f68f | 541 | tty_schedule_flip(port); |
e0495736 AC |
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. | |
e0495736 AC |
551 | */ |
552 | ||
ecbbfd44 | 553 | void tty_buffer_init(struct tty_port *port) |
e0495736 | 554 | { |
ecbbfd44 | 555 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 556 | |
a7c8d58c | 557 | mutex_init(&buf->lock); |
7391ee16 PH |
558 | tty_buffer_reset(&buf->sentinel, 0); |
559 | buf->head = &buf->sentinel; | |
560 | buf->tail = &buf->sentinel; | |
809850b7 | 561 | init_llist_head(&buf->free); |
5dda4ca5 | 562 | atomic_set(&buf->mem_used, 0); |
a7c8d58c | 563 | atomic_set(&buf->priority, 0); |
5cff39c6 | 564 | INIT_WORK(&buf->work, flush_to_ldisc); |
4d18e6ef | 565 | buf->mem_limit = TTYB_DEFAULT_MEM_LIMIT; |
e0495736 | 566 | } |
4d18e6ef PH |
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); | |
1d1d14da PH |
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 | } | |
e176058f PH |
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 | } |