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Commit | Line | Data |
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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> | |
14 | #include <linux/init.h> | |
15 | #include <linux/wait.h> | |
16 | #include <linux/bitops.h> | |
17 | #include <linux/delay.h> | |
18 | #include <linux/module.h> | |
593fb1ae | 19 | #include <linux/ratelimit.h> |
e0495736 | 20 | |
1cef50e3 PH |
21 | |
22 | #define MIN_TTYB_SIZE 256 | |
23 | #define TTYB_ALIGN_MASK 255 | |
24 | ||
7bfe0b71 PH |
25 | /* |
26 | * Byte threshold to limit memory consumption for flip buffers. | |
27 | * The actual memory limit is > 2x this amount. | |
28 | */ | |
29 | #define TTYB_MEM_LIMIT 65536 | |
30 | ||
31 | ||
32 | /** | |
33 | * tty_buffer_space_avail - return unused buffer space | |
34 | * @port - tty_port owning the flip buffer | |
35 | * | |
36 | * Returns the # of bytes which can be written by the driver without | |
37 | * reaching the buffer limit. | |
38 | * | |
39 | * Note: this does not guarantee that memory is available to write | |
40 | * the returned # of bytes (use tty_prepare_flip_string_xxx() to | |
41 | * pre-allocate if memory guarantee is required). | |
42 | */ | |
43 | ||
44 | int tty_buffer_space_avail(struct tty_port *port) | |
45 | { | |
46 | int space = TTYB_MEM_LIMIT - atomic_read(&port->buf.memory_used); | |
47 | return max(space, 0); | |
48 | } | |
49 | ||
9dd5139f PH |
50 | static void tty_buffer_reset(struct tty_buffer *p, size_t size) |
51 | { | |
52 | p->used = 0; | |
53 | p->size = size; | |
54 | p->next = NULL; | |
55 | p->commit = 0; | |
56 | p->read = 0; | |
57 | } | |
58 | ||
e0495736 AC |
59 | /** |
60 | * tty_buffer_free_all - free buffers used by a tty | |
61 | * @tty: tty to free from | |
62 | * | |
63 | * Remove all the buffers pending on a tty whether queued with data | |
64 | * or in the free ring. Must be called when the tty is no longer in use | |
e0495736 AC |
65 | */ |
66 | ||
ecbbfd44 | 67 | void tty_buffer_free_all(struct tty_port *port) |
e0495736 | 68 | { |
ecbbfd44 | 69 | struct tty_bufhead *buf = &port->buf; |
809850b7 PH |
70 | struct tty_buffer *p, *next; |
71 | struct llist_node *llist; | |
5cff39c6 | 72 | |
2cf7b67e PH |
73 | while ((p = buf->head) != NULL) { |
74 | buf->head = p->next; | |
7391ee16 PH |
75 | if (p->size > 0) |
76 | kfree(p); | |
e0495736 | 77 | } |
809850b7 PH |
78 | llist = llist_del_all(&buf->free); |
79 | llist_for_each_entry_safe(p, next, llist, free) | |
2cf7b67e | 80 | kfree(p); |
809850b7 | 81 | |
7391ee16 PH |
82 | tty_buffer_reset(&buf->sentinel, 0); |
83 | buf->head = &buf->sentinel; | |
84 | buf->tail = &buf->sentinel; | |
7bfe0b71 PH |
85 | |
86 | atomic_set(&buf->memory_used, 0); | |
e0495736 AC |
87 | } |
88 | ||
89 | /** | |
90 | * tty_buffer_alloc - allocate a tty buffer | |
91 | * @tty: tty device | |
92 | * @size: desired size (characters) | |
93 | * | |
94 | * Allocate a new tty buffer to hold the desired number of characters. | |
11b9faa4 PH |
95 | * We round our buffers off in 256 character chunks to get better |
96 | * allocation behaviour. | |
e0495736 AC |
97 | * Return NULL if out of memory or the allocation would exceed the |
98 | * per device queue | |
e0495736 AC |
99 | */ |
100 | ||
ecbbfd44 | 101 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
e0495736 | 102 | { |
809850b7 | 103 | struct llist_node *free; |
e0495736 AC |
104 | struct tty_buffer *p; |
105 | ||
11b9faa4 PH |
106 | /* Round the buffer size out */ |
107 | size = __ALIGN_MASK(size, TTYB_ALIGN_MASK); | |
108 | ||
109 | if (size <= MIN_TTYB_SIZE) { | |
809850b7 PH |
110 | free = llist_del_first(&port->buf.free); |
111 | if (free) { | |
112 | p = llist_entry(free, struct tty_buffer, free); | |
11b9faa4 PH |
113 | goto found; |
114 | } | |
115 | } | |
116 | ||
117 | /* Should possibly check if this fails for the largest buffer we | |
118 | have queued and recycle that ? */ | |
7bfe0b71 | 119 | if (atomic_read(&port->buf.memory_used) > TTYB_MEM_LIMIT) |
e0495736 AC |
120 | return NULL; |
121 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); | |
122 | if (p == NULL) | |
123 | return NULL; | |
9dd5139f | 124 | |
11b9faa4 | 125 | found: |
9dd5139f | 126 | tty_buffer_reset(p, size); |
7bfe0b71 | 127 | atomic_add(size, &port->buf.memory_used); |
e0495736 AC |
128 | return p; |
129 | } | |
130 | ||
131 | /** | |
132 | * tty_buffer_free - free a tty buffer | |
133 | * @tty: tty owning the buffer | |
134 | * @b: the buffer to free | |
135 | * | |
136 | * Free a tty buffer, or add it to the free list according to our | |
137 | * internal strategy | |
e0495736 AC |
138 | */ |
139 | ||
ecbbfd44 | 140 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 141 | { |
ecbbfd44 | 142 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 143 | |
e0495736 | 144 | /* Dumb strategy for now - should keep some stats */ |
7bfe0b71 | 145 | WARN_ON(atomic_sub_return(b->size, &buf->memory_used) < 0); |
e0495736 | 146 | |
1cef50e3 | 147 | if (b->size > MIN_TTYB_SIZE) |
e0495736 | 148 | kfree(b); |
7391ee16 | 149 | else if (b->size > 0) |
809850b7 | 150 | llist_add(&b->free, &buf->free); |
e0495736 AC |
151 | } |
152 | ||
153 | /** | |
154 | * __tty_buffer_flush - flush full tty buffers | |
155 | * @tty: tty to flush | |
156 | * | |
157 | * flush all the buffers containing receive data. Caller must | |
158 | * hold the buffer lock and must have ensured no parallel flush to | |
159 | * ldisc is running. | |
e0495736 AC |
160 | */ |
161 | ||
ecbbfd44 | 162 | static void __tty_buffer_flush(struct tty_port *port) |
e0495736 | 163 | { |
ecbbfd44 | 164 | struct tty_bufhead *buf = &port->buf; |
2cf7b67e | 165 | struct tty_buffer *next; |
e0495736 | 166 | |
2cf7b67e | 167 | while ((next = buf->head->next) != NULL) { |
64325a3b | 168 | tty_buffer_free(port, buf->head); |
2cf7b67e | 169 | buf->head = next; |
e0495736 | 170 | } |
64325a3b IZ |
171 | WARN_ON(buf->head != buf->tail); |
172 | buf->head->read = buf->head->commit; | |
e0495736 AC |
173 | } |
174 | ||
175 | /** | |
176 | * tty_buffer_flush - flush full tty buffers | |
177 | * @tty: tty to flush | |
178 | * | |
179 | * flush all the buffers containing receive data. If the buffer is | |
180 | * being processed by flush_to_ldisc then we defer the processing | |
181 | * to that function | |
182 | * | |
e9975fde PH |
183 | * Locking: takes flush_mutex to ensure single-threaded flip buffer |
184 | * 'consumer' | |
e0495736 AC |
185 | */ |
186 | ||
187 | void tty_buffer_flush(struct tty_struct *tty) | |
188 | { | |
2fc20661 | 189 | struct tty_port *port = tty->port; |
ecbbfd44 | 190 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 191 | |
e9975fde | 192 | mutex_lock(&buf->flush_mutex); |
e0495736 AC |
193 | /* If the data is being pushed to the tty layer then we can't |
194 | process it here. Instead set a flag and the flush_to_ldisc | |
195 | path will process the flush request before it exits */ | |
2fc20661 JS |
196 | if (test_bit(TTYP_FLUSHING, &port->iflags)) { |
197 | set_bit(TTYP_FLUSHPENDING, &port->iflags); | |
e9975fde | 198 | mutex_unlock(&buf->flush_mutex); |
e0495736 | 199 | wait_event(tty->read_wait, |
2fc20661 | 200 | test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); |
e0495736 | 201 | return; |
e9975fde PH |
202 | } |
203 | ||
204 | __tty_buffer_flush(port); | |
205 | mutex_unlock(&buf->flush_mutex); | |
e0495736 AC |
206 | } |
207 | ||
e0495736 | 208 | /** |
64325a3b | 209 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
210 | * @tty: tty structure |
211 | * @size: size desired | |
212 | * | |
213 | * Make at least size bytes of linear space available for the tty | |
214 | * buffer. If we fail return the size we managed to find. | |
e0495736 | 215 | */ |
64325a3b | 216 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
e0495736 | 217 | { |
ecbbfd44 | 218 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
219 | struct tty_buffer *b, *n; |
220 | int left; | |
e8437d7e | 221 | |
5cff39c6 | 222 | b = buf->tail; |
7391ee16 | 223 | left = b->size - b->used; |
e0495736 AC |
224 | |
225 | if (left < size) { | |
226 | /* This is the slow path - looking for new buffers to use */ | |
11b9faa4 | 227 | if ((n = tty_buffer_alloc(port, size)) != NULL) { |
5cff39c6 | 228 | buf->tail = n; |
e8437d7e PH |
229 | b->commit = b->used; |
230 | smp_mb(); | |
231 | b->next = n; | |
e0495736 AC |
232 | } else |
233 | size = left; | |
234 | } | |
e0495736 AC |
235 | return size; |
236 | } | |
237 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); | |
238 | ||
239 | /** | |
2832fc11 | 240 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 241 | * @port: tty port |
e0495736 | 242 | * @chars: characters |
2832fc11 | 243 | * @flag: flag value for each character |
e0495736 AC |
244 | * @size: size |
245 | * | |
246 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 247 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 AC |
248 | */ |
249 | ||
2f693357 | 250 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 251 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
252 | { |
253 | int copied = 0; | |
254 | do { | |
d4bee0a6 | 255 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
256 | int space = tty_buffer_request_room(port, goal); |
257 | struct tty_buffer *tb = port->buf.tail; | |
7391ee16 | 258 | if (unlikely(space == 0)) |
e0495736 | 259 | break; |
1fc359fc PH |
260 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
261 | memset(flag_buf_ptr(tb, tb->used), flag, space); | |
e0495736 AC |
262 | tb->used += space; |
263 | copied += space; | |
264 | chars += space; | |
265 | /* There is a small chance that we need to split the data over | |
266 | several buffers. If this is the case we must loop */ | |
267 | } while (unlikely(size > copied)); | |
268 | return copied; | |
269 | } | |
2832fc11 | 270 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
271 | |
272 | /** | |
273 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 274 | * @port: tty port |
e0495736 AC |
275 | * @chars: characters |
276 | * @flags: flag bytes | |
277 | * @size: size | |
278 | * | |
279 | * Queue a series of bytes to the tty buffering. For each character | |
280 | * the flags array indicates the status of the character. Returns the | |
281 | * number added. | |
e0495736 AC |
282 | */ |
283 | ||
2f693357 | 284 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
285 | const unsigned char *chars, const char *flags, size_t size) |
286 | { | |
287 | int copied = 0; | |
288 | do { | |
d4bee0a6 | 289 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
290 | int space = tty_buffer_request_room(port, goal); |
291 | struct tty_buffer *tb = port->buf.tail; | |
7391ee16 | 292 | if (unlikely(space == 0)) |
e0495736 | 293 | break; |
1fc359fc PH |
294 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
295 | memcpy(flag_buf_ptr(tb, tb->used), flags, space); | |
e0495736 AC |
296 | tb->used += space; |
297 | copied += space; | |
298 | chars += space; | |
299 | flags += space; | |
300 | /* There is a small chance that we need to split the data over | |
301 | several buffers. If this is the case we must loop */ | |
302 | } while (unlikely(size > copied)); | |
303 | return copied; | |
304 | } | |
305 | EXPORT_SYMBOL(tty_insert_flip_string_flags); | |
306 | ||
307 | /** | |
308 | * tty_schedule_flip - push characters to ldisc | |
6732c8bb | 309 | * @port: tty port to push from |
e0495736 AC |
310 | * |
311 | * Takes any pending buffers and transfers their ownership to the | |
312 | * ldisc side of the queue. It then schedules those characters for | |
313 | * processing by the line discipline. | |
cee4ad1e IS |
314 | * Note that this function can only be used when the low_latency flag |
315 | * is unset. Otherwise the workqueue won't be flushed. | |
e0495736 AC |
316 | */ |
317 | ||
6732c8bb | 318 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 319 | { |
6732c8bb | 320 | struct tty_bufhead *buf = &port->buf; |
6732c8bb | 321 | WARN_ON(port->low_latency); |
5cff39c6 | 322 | |
7391ee16 | 323 | buf->tail->commit = buf->tail->used; |
5cff39c6 | 324 | schedule_work(&buf->work); |
e0495736 AC |
325 | } |
326 | EXPORT_SYMBOL(tty_schedule_flip); | |
327 | ||
328 | /** | |
329 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 330 | * @port: tty port |
e0495736 AC |
331 | * @chars: return pointer for character write area |
332 | * @size: desired size | |
333 | * | |
334 | * Prepare a block of space in the buffer for data. Returns the length | |
335 | * available and buffer pointer to the space which is now allocated and | |
336 | * accounted for as ready for normal characters. This is used for drivers | |
337 | * that need their own block copy routines into the buffer. There is no | |
338 | * guarantee the buffer is a DMA target! | |
e0495736 AC |
339 | */ |
340 | ||
2f693357 | 341 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 342 | size_t size) |
e0495736 | 343 | { |
64325a3b | 344 | int space = tty_buffer_request_room(port, size); |
e0495736 | 345 | if (likely(space)) { |
64325a3b | 346 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
347 | *chars = char_buf_ptr(tb, tb->used); |
348 | memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space); | |
e0495736 AC |
349 | tb->used += space; |
350 | } | |
351 | return space; | |
352 | } | |
353 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
354 | ||
355 | /** | |
356 | * tty_prepare_flip_string_flags - make room for characters | |
2f693357 | 357 | * @port: tty port |
e0495736 AC |
358 | * @chars: return pointer for character write area |
359 | * @flags: return pointer for status flag write area | |
360 | * @size: desired size | |
361 | * | |
362 | * Prepare a block of space in the buffer for data. Returns the length | |
363 | * available and buffer pointer to the space which is now allocated and | |
364 | * accounted for as ready for characters. This is used for drivers | |
365 | * that need their own block copy routines into the buffer. There is no | |
366 | * guarantee the buffer is a DMA target! | |
e0495736 AC |
367 | */ |
368 | ||
2f693357 | 369 | int tty_prepare_flip_string_flags(struct tty_port *port, |
e0495736 AC |
370 | unsigned char **chars, char **flags, size_t size) |
371 | { | |
64325a3b | 372 | int space = tty_buffer_request_room(port, size); |
e0495736 | 373 | if (likely(space)) { |
64325a3b | 374 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
375 | *chars = char_buf_ptr(tb, tb->used); |
376 | *flags = flag_buf_ptr(tb, tb->used); | |
e0495736 AC |
377 | tb->used += space; |
378 | } | |
379 | return space; | |
380 | } | |
381 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); | |
382 | ||
383 | ||
da261e7f PH |
384 | static int |
385 | receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) | |
386 | { | |
387 | struct tty_ldisc *disc = tty->ldisc; | |
1fc359fc PH |
388 | unsigned char *p = char_buf_ptr(head, head->read); |
389 | char *f = flag_buf_ptr(head, head->read); | |
da261e7f | 390 | |
24a89d1c PH |
391 | if (disc->ops->receive_buf2) |
392 | count = disc->ops->receive_buf2(tty, p, f, count); | |
393 | else { | |
394 | count = min_t(int, count, tty->receive_room); | |
395 | if (count) | |
396 | disc->ops->receive_buf(tty, p, f, count); | |
397 | } | |
da261e7f PH |
398 | head->read += count; |
399 | return count; | |
400 | } | |
e0495736 AC |
401 | |
402 | /** | |
403 | * flush_to_ldisc | |
404 | * @work: tty structure passed from work queue. | |
405 | * | |
406 | * This routine is called out of the software interrupt to flush data | |
407 | * from the buffer chain to the line discipline. | |
408 | * | |
e9975fde PH |
409 | * The receive_buf method is single threaded for each tty instance. |
410 | * | |
411 | * Locking: takes flush_mutex to ensure single-threaded flip buffer | |
412 | * 'consumer' | |
e0495736 AC |
413 | */ |
414 | ||
415 | static void flush_to_ldisc(struct work_struct *work) | |
416 | { | |
ecbbfd44 JS |
417 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
418 | struct tty_bufhead *buf = &port->buf; | |
419 | struct tty_struct *tty; | |
e0495736 | 420 | struct tty_ldisc *disc; |
e0495736 | 421 | |
ecbbfd44 | 422 | tty = port->itty; |
34dcfb84 | 423 | if (tty == NULL) |
ecbbfd44 JS |
424 | return; |
425 | ||
e0495736 | 426 | disc = tty_ldisc_ref(tty); |
36697529 | 427 | if (disc == NULL) |
e0495736 AC |
428 | return; |
429 | ||
e9975fde | 430 | mutex_lock(&buf->flush_mutex); |
45242006 | 431 | |
2fc20661 | 432 | if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { |
7391ee16 PH |
433 | while (1) { |
434 | struct tty_buffer *head = buf->head; | |
45242006 | 435 | int count; |
45242006 LT |
436 | |
437 | count = head->commit - head->read; | |
e0495736 AC |
438 | if (!count) { |
439 | if (head->next == NULL) | |
440 | break; | |
5cff39c6 | 441 | buf->head = head->next; |
ecbbfd44 | 442 | tty_buffer_free(port, head); |
e0495736 AC |
443 | continue; |
444 | } | |
e9975fde PH |
445 | |
446 | mutex_unlock(&buf->flush_mutex); | |
da261e7f PH |
447 | |
448 | count = receive_buf(tty, head, count); | |
449 | ||
e9975fde PH |
450 | mutex_lock(&buf->flush_mutex); |
451 | ||
39f610e4 PH |
452 | /* Ldisc or user is trying to flush the buffers. |
453 | We may have a deferred request to flush the | |
454 | input buffer, if so pull the chain under the lock | |
455 | and empty the queue */ | |
456 | if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) { | |
457 | __tty_buffer_flush(port); | |
458 | clear_bit(TTYP_FLUSHPENDING, &port->iflags); | |
459 | wake_up(&tty->read_wait); | |
460 | break; | |
da261e7f PH |
461 | } else if (!count) |
462 | break; | |
e0495736 | 463 | } |
2fc20661 | 464 | clear_bit(TTYP_FLUSHING, &port->iflags); |
e0495736 | 465 | } |
45242006 | 466 | |
e9975fde | 467 | mutex_unlock(&buf->flush_mutex); |
e0495736 AC |
468 | |
469 | tty_ldisc_deref(disc); | |
470 | } | |
471 | ||
e043e42b OH |
472 | /** |
473 | * tty_flush_to_ldisc | |
474 | * @tty: tty to push | |
475 | * | |
476 | * Push the terminal flip buffers to the line discipline. | |
477 | * | |
478 | * Must not be called from IRQ context. | |
479 | */ | |
480 | void tty_flush_to_ldisc(struct tty_struct *tty) | |
481 | { | |
d6c53c0e | 482 | if (!tty->port->low_latency) |
ecbbfd44 | 483 | flush_work(&tty->port->buf.work); |
e043e42b OH |
484 | } |
485 | ||
e0495736 AC |
486 | /** |
487 | * tty_flip_buffer_push - terminal | |
2e124b4a | 488 | * @port: tty port to push |
e0495736 AC |
489 | * |
490 | * Queue a push of the terminal flip buffers to the line discipline. This | |
d6c53c0e JS |
491 | * function must not be called from IRQ context if port->low_latency is |
492 | * set. | |
e0495736 AC |
493 | * |
494 | * In the event of the queue being busy for flipping the work will be | |
495 | * held off and retried later. | |
e0495736 AC |
496 | */ |
497 | ||
2e124b4a | 498 | void tty_flip_buffer_push(struct tty_port *port) |
e0495736 | 499 | { |
2e124b4a | 500 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 501 | |
7391ee16 | 502 | buf->tail->commit = buf->tail->used; |
e0495736 | 503 | |
2e124b4a | 504 | if (port->low_latency) |
5cff39c6 | 505 | flush_to_ldisc(&buf->work); |
e0495736 | 506 | else |
5cff39c6 | 507 | schedule_work(&buf->work); |
e0495736 AC |
508 | } |
509 | EXPORT_SYMBOL(tty_flip_buffer_push); | |
510 | ||
511 | /** | |
512 | * tty_buffer_init - prepare a tty buffer structure | |
513 | * @tty: tty to initialise | |
514 | * | |
515 | * Set up the initial state of the buffer management for a tty device. | |
516 | * Must be called before the other tty buffer functions are used. | |
e0495736 AC |
517 | */ |
518 | ||
ecbbfd44 | 519 | void tty_buffer_init(struct tty_port *port) |
e0495736 | 520 | { |
ecbbfd44 | 521 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 522 | |
e9975fde | 523 | mutex_init(&buf->flush_mutex); |
7391ee16 PH |
524 | tty_buffer_reset(&buf->sentinel, 0); |
525 | buf->head = &buf->sentinel; | |
526 | buf->tail = &buf->sentinel; | |
809850b7 | 527 | init_llist_head(&buf->free); |
7bfe0b71 | 528 | atomic_set(&buf->memory_used, 0); |
5cff39c6 | 529 | INIT_WORK(&buf->work, flush_to_ldisc); |
e0495736 AC |
530 | } |
531 |