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> | |
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 AC |
20 | |
21 | /** | |
22 | * tty_buffer_free_all - free buffers used by a tty | |
23 | * @tty: tty to free from | |
24 | * | |
25 | * Remove all the buffers pending on a tty whether queued with data | |
26 | * or in the free ring. Must be called when the tty is no longer in use | |
27 | * | |
28 | * Locking: none | |
29 | */ | |
30 | ||
ecbbfd44 | 31 | void tty_buffer_free_all(struct tty_port *port) |
e0495736 | 32 | { |
ecbbfd44 | 33 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 34 | struct tty_buffer *thead; |
5cff39c6 JS |
35 | |
36 | while ((thead = buf->head) != NULL) { | |
37 | buf->head = thead->next; | |
e0495736 AC |
38 | kfree(thead); |
39 | } | |
5cff39c6 JS |
40 | while ((thead = buf->free) != NULL) { |
41 | buf->free = thead->next; | |
e0495736 AC |
42 | kfree(thead); |
43 | } | |
5cff39c6 JS |
44 | buf->tail = NULL; |
45 | buf->memory_used = 0; | |
e0495736 AC |
46 | } |
47 | ||
48 | /** | |
49 | * tty_buffer_alloc - allocate a tty buffer | |
50 | * @tty: tty device | |
51 | * @size: desired size (characters) | |
52 | * | |
53 | * Allocate a new tty buffer to hold the desired number of characters. | |
54 | * Return NULL if out of memory or the allocation would exceed the | |
55 | * per device queue | |
56 | * | |
57 | * Locking: Caller must hold tty->buf.lock | |
58 | */ | |
59 | ||
ecbbfd44 | 60 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
e0495736 AC |
61 | { |
62 | struct tty_buffer *p; | |
63 | ||
ecbbfd44 | 64 | if (port->buf.memory_used + size > 65536) |
e0495736 AC |
65 | return NULL; |
66 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); | |
67 | if (p == NULL) | |
68 | return NULL; | |
69 | p->used = 0; | |
70 | p->size = size; | |
71 | p->next = NULL; | |
72 | p->commit = 0; | |
73 | p->read = 0; | |
74 | p->char_buf_ptr = (char *)(p->data); | |
75 | p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size; | |
ecbbfd44 | 76 | port->buf.memory_used += size; |
e0495736 AC |
77 | return p; |
78 | } | |
79 | ||
80 | /** | |
81 | * tty_buffer_free - free a tty buffer | |
82 | * @tty: tty owning the buffer | |
83 | * @b: the buffer to free | |
84 | * | |
85 | * Free a tty buffer, or add it to the free list according to our | |
86 | * internal strategy | |
87 | * | |
88 | * Locking: Caller must hold tty->buf.lock | |
89 | */ | |
90 | ||
ecbbfd44 | 91 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 92 | { |
ecbbfd44 | 93 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 94 | |
e0495736 | 95 | /* Dumb strategy for now - should keep some stats */ |
5cff39c6 JS |
96 | buf->memory_used -= b->size; |
97 | WARN_ON(buf->memory_used < 0); | |
e0495736 AC |
98 | |
99 | if (b->size >= 512) | |
100 | kfree(b); | |
101 | else { | |
5cff39c6 JS |
102 | b->next = buf->free; |
103 | buf->free = b; | |
e0495736 AC |
104 | } |
105 | } | |
106 | ||
107 | /** | |
108 | * __tty_buffer_flush - flush full tty buffers | |
109 | * @tty: tty to flush | |
110 | * | |
111 | * flush all the buffers containing receive data. Caller must | |
112 | * hold the buffer lock and must have ensured no parallel flush to | |
113 | * ldisc is running. | |
114 | * | |
115 | * Locking: Caller must hold tty->buf.lock | |
116 | */ | |
117 | ||
ecbbfd44 | 118 | static void __tty_buffer_flush(struct tty_port *port) |
e0495736 | 119 | { |
ecbbfd44 | 120 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
121 | struct tty_buffer *thead; |
122 | ||
64325a3b IZ |
123 | if (unlikely(buf->head == NULL)) |
124 | return; | |
125 | while ((thead = buf->head->next) != NULL) { | |
126 | tty_buffer_free(port, buf->head); | |
127 | buf->head = thead; | |
e0495736 | 128 | } |
64325a3b IZ |
129 | WARN_ON(buf->head != buf->tail); |
130 | buf->head->read = buf->head->commit; | |
e0495736 AC |
131 | } |
132 | ||
133 | /** | |
134 | * tty_buffer_flush - flush full tty buffers | |
135 | * @tty: tty to flush | |
136 | * | |
137 | * flush all the buffers containing receive data. If the buffer is | |
138 | * being processed by flush_to_ldisc then we defer the processing | |
139 | * to that function | |
140 | * | |
141 | * Locking: none | |
142 | */ | |
143 | ||
144 | void tty_buffer_flush(struct tty_struct *tty) | |
145 | { | |
2fc20661 | 146 | struct tty_port *port = tty->port; |
ecbbfd44 | 147 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 148 | unsigned long flags; |
5cff39c6 JS |
149 | |
150 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
151 | |
152 | /* If the data is being pushed to the tty layer then we can't | |
153 | process it here. Instead set a flag and the flush_to_ldisc | |
154 | path will process the flush request before it exits */ | |
2fc20661 JS |
155 | if (test_bit(TTYP_FLUSHING, &port->iflags)) { |
156 | set_bit(TTYP_FLUSHPENDING, &port->iflags); | |
5cff39c6 | 157 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 | 158 | wait_event(tty->read_wait, |
2fc20661 | 159 | test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); |
e0495736 AC |
160 | return; |
161 | } else | |
ecbbfd44 | 162 | __tty_buffer_flush(port); |
5cff39c6 | 163 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
164 | } |
165 | ||
166 | /** | |
167 | * tty_buffer_find - find a free tty buffer | |
168 | * @tty: tty owning the buffer | |
169 | * @size: characters wanted | |
170 | * | |
171 | * Locate an existing suitable tty buffer or if we are lacking one then | |
172 | * allocate a new one. We round our buffers off in 256 character chunks | |
173 | * to get better allocation behaviour. | |
174 | * | |
175 | * Locking: Caller must hold tty->buf.lock | |
176 | */ | |
177 | ||
ecbbfd44 | 178 | static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size) |
e0495736 | 179 | { |
ecbbfd44 | 180 | struct tty_buffer **tbh = &port->buf.free; |
e0495736 AC |
181 | while ((*tbh) != NULL) { |
182 | struct tty_buffer *t = *tbh; | |
183 | if (t->size >= size) { | |
184 | *tbh = t->next; | |
185 | t->next = NULL; | |
186 | t->used = 0; | |
187 | t->commit = 0; | |
188 | t->read = 0; | |
ecbbfd44 | 189 | port->buf.memory_used += t->size; |
e0495736 AC |
190 | return t; |
191 | } | |
192 | tbh = &((*tbh)->next); | |
193 | } | |
194 | /* Round the buffer size out */ | |
195 | size = (size + 0xFF) & ~0xFF; | |
ecbbfd44 | 196 | return tty_buffer_alloc(port, size); |
e0495736 AC |
197 | /* Should possibly check if this fails for the largest buffer we |
198 | have queued and recycle that ? */ | |
199 | } | |
e0495736 | 200 | /** |
64325a3b | 201 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
202 | * @tty: tty structure |
203 | * @size: size desired | |
204 | * | |
205 | * Make at least size bytes of linear space available for the tty | |
206 | * buffer. If we fail return the size we managed to find. | |
64325a3b IZ |
207 | * |
208 | * Locking: Takes port->buf.lock | |
e0495736 | 209 | */ |
64325a3b | 210 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
e0495736 | 211 | { |
ecbbfd44 | 212 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
213 | struct tty_buffer *b, *n; |
214 | int left; | |
64325a3b IZ |
215 | unsigned long flags; |
216 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
217 | /* OPTIMISATION: We could keep a per tty "zero" sized buffer to |
218 | remove this conditional if its worth it. This would be invisible | |
219 | to the callers */ | |
5cff39c6 JS |
220 | b = buf->tail; |
221 | if (b != NULL) | |
e0495736 AC |
222 | left = b->size - b->used; |
223 | else | |
224 | left = 0; | |
225 | ||
226 | if (left < size) { | |
227 | /* This is the slow path - looking for new buffers to use */ | |
ecbbfd44 | 228 | if ((n = tty_buffer_find(port, size)) != NULL) { |
e0495736 AC |
229 | if (b != NULL) { |
230 | b->next = n; | |
231 | b->commit = b->used; | |
232 | } else | |
5cff39c6 JS |
233 | buf->head = n; |
234 | buf->tail = n; | |
e0495736 AC |
235 | } else |
236 | size = left; | |
237 | } | |
64325a3b | 238 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
239 | return size; |
240 | } | |
241 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); | |
242 | ||
243 | /** | |
2832fc11 | 244 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 245 | * @port: tty port |
e0495736 | 246 | * @chars: characters |
2832fc11 | 247 | * @flag: flag value for each character |
e0495736 AC |
248 | * @size: size |
249 | * | |
250 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 251 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 | 252 | * |
ecbbfd44 | 253 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
254 | */ |
255 | ||
2f693357 | 256 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 257 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
258 | { |
259 | int copied = 0; | |
260 | do { | |
d4bee0a6 | 261 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
262 | int space = tty_buffer_request_room(port, goal); |
263 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 264 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 265 | if (unlikely(space == 0)) { |
e0495736 | 266 | break; |
c56a00a1 | 267 | } |
e0495736 | 268 | memcpy(tb->char_buf_ptr + tb->used, chars, space); |
2832fc11 | 269 | memset(tb->flag_buf_ptr + tb->used, flag, space); |
e0495736 AC |
270 | tb->used += space; |
271 | copied += space; | |
272 | chars += space; | |
273 | /* There is a small chance that we need to split the data over | |
274 | several buffers. If this is the case we must loop */ | |
275 | } while (unlikely(size > copied)); | |
276 | return copied; | |
277 | } | |
2832fc11 | 278 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
279 | |
280 | /** | |
281 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 282 | * @port: tty port |
e0495736 AC |
283 | * @chars: characters |
284 | * @flags: flag bytes | |
285 | * @size: size | |
286 | * | |
287 | * Queue a series of bytes to the tty buffering. For each character | |
288 | * the flags array indicates the status of the character. Returns the | |
289 | * number added. | |
290 | * | |
ecbbfd44 | 291 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
292 | */ |
293 | ||
2f693357 | 294 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
295 | const unsigned char *chars, const char *flags, size_t size) |
296 | { | |
297 | int copied = 0; | |
298 | do { | |
d4bee0a6 | 299 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
300 | int space = tty_buffer_request_room(port, goal); |
301 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 302 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 303 | if (unlikely(space == 0)) { |
e0495736 | 304 | break; |
c56a00a1 | 305 | } |
e0495736 AC |
306 | memcpy(tb->char_buf_ptr + tb->used, chars, space); |
307 | memcpy(tb->flag_buf_ptr + tb->used, flags, space); | |
308 | tb->used += space; | |
309 | copied += space; | |
310 | chars += space; | |
311 | flags += space; | |
312 | /* There is a small chance that we need to split the data over | |
313 | several buffers. If this is the case we must loop */ | |
314 | } while (unlikely(size > copied)); | |
315 | return copied; | |
316 | } | |
317 | EXPORT_SYMBOL(tty_insert_flip_string_flags); | |
318 | ||
319 | /** | |
320 | * tty_schedule_flip - push characters to ldisc | |
6732c8bb | 321 | * @port: tty port to push from |
e0495736 AC |
322 | * |
323 | * Takes any pending buffers and transfers their ownership to the | |
324 | * ldisc side of the queue. It then schedules those characters for | |
325 | * processing by the line discipline. | |
cee4ad1e IS |
326 | * Note that this function can only be used when the low_latency flag |
327 | * is unset. Otherwise the workqueue won't be flushed. | |
e0495736 | 328 | * |
ecbbfd44 | 329 | * Locking: Takes port->buf.lock |
e0495736 AC |
330 | */ |
331 | ||
6732c8bb | 332 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 333 | { |
6732c8bb | 334 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 335 | unsigned long flags; |
6732c8bb | 336 | WARN_ON(port->low_latency); |
5cff39c6 JS |
337 | |
338 | spin_lock_irqsave(&buf->lock, flags); | |
339 | if (buf->tail != NULL) | |
340 | buf->tail->commit = buf->tail->used; | |
341 | spin_unlock_irqrestore(&buf->lock, flags); | |
342 | schedule_work(&buf->work); | |
e0495736 AC |
343 | } |
344 | EXPORT_SYMBOL(tty_schedule_flip); | |
345 | ||
346 | /** | |
347 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 348 | * @port: tty port |
e0495736 AC |
349 | * @chars: return pointer for character write area |
350 | * @size: desired size | |
351 | * | |
352 | * Prepare a block of space in the buffer for data. Returns the length | |
353 | * available and buffer pointer to the space which is now allocated and | |
354 | * accounted for as ready for normal characters. This is used for drivers | |
355 | * that need their own block copy routines into the buffer. There is no | |
356 | * guarantee the buffer is a DMA target! | |
357 | * | |
ecbbfd44 | 358 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
359 | */ |
360 | ||
2f693357 | 361 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 362 | size_t size) |
e0495736 | 363 | { |
64325a3b | 364 | int space = tty_buffer_request_room(port, size); |
e0495736 | 365 | if (likely(space)) { |
64325a3b | 366 | struct tty_buffer *tb = port->buf.tail; |
e0495736 AC |
367 | *chars = tb->char_buf_ptr + tb->used; |
368 | memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space); | |
369 | tb->used += space; | |
370 | } | |
371 | return space; | |
372 | } | |
373 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
374 | ||
375 | /** | |
376 | * tty_prepare_flip_string_flags - make room for characters | |
2f693357 | 377 | * @port: tty port |
e0495736 AC |
378 | * @chars: return pointer for character write area |
379 | * @flags: return pointer for status flag write area | |
380 | * @size: desired size | |
381 | * | |
382 | * Prepare a block of space in the buffer for data. Returns the length | |
383 | * available and buffer pointer to the space which is now allocated and | |
384 | * accounted for as ready for characters. This is used for drivers | |
385 | * that need their own block copy routines into the buffer. There is no | |
386 | * guarantee the buffer is a DMA target! | |
387 | * | |
ecbbfd44 | 388 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
389 | */ |
390 | ||
2f693357 | 391 | int tty_prepare_flip_string_flags(struct tty_port *port, |
e0495736 AC |
392 | unsigned char **chars, char **flags, size_t size) |
393 | { | |
64325a3b | 394 | int space = tty_buffer_request_room(port, size); |
e0495736 | 395 | if (likely(space)) { |
64325a3b | 396 | struct tty_buffer *tb = port->buf.tail; |
e0495736 AC |
397 | *chars = tb->char_buf_ptr + tb->used; |
398 | *flags = tb->flag_buf_ptr + tb->used; | |
399 | tb->used += space; | |
400 | } | |
401 | return space; | |
402 | } | |
403 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); | |
404 | ||
405 | ||
406 | ||
407 | /** | |
408 | * flush_to_ldisc | |
409 | * @work: tty structure passed from work queue. | |
410 | * | |
411 | * This routine is called out of the software interrupt to flush data | |
412 | * from the buffer chain to the line discipline. | |
413 | * | |
414 | * Locking: holds tty->buf.lock to guard buffer list. Drops the lock | |
415 | * while invoking the line discipline receive_buf method. The | |
416 | * receive_buf method is single threaded for each tty instance. | |
417 | */ | |
418 | ||
419 | static void flush_to_ldisc(struct work_struct *work) | |
420 | { | |
ecbbfd44 JS |
421 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
422 | struct tty_bufhead *buf = &port->buf; | |
423 | struct tty_struct *tty; | |
e0495736 AC |
424 | unsigned long flags; |
425 | struct tty_ldisc *disc; | |
e0495736 | 426 | |
ecbbfd44 | 427 | tty = port->itty; |
34dcfb84 | 428 | if (tty == NULL) |
ecbbfd44 JS |
429 | return; |
430 | ||
e0495736 AC |
431 | disc = tty_ldisc_ref(tty); |
432 | if (disc == NULL) /* !TTY_LDISC */ | |
433 | return; | |
434 | ||
5cff39c6 | 435 | spin_lock_irqsave(&buf->lock, flags); |
45242006 | 436 | |
2fc20661 | 437 | if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { |
81de916f | 438 | struct tty_buffer *head; |
5cff39c6 | 439 | while ((head = buf->head) != NULL) { |
45242006 LT |
440 | int count; |
441 | char *char_buf; | |
442 | unsigned char *flag_buf; | |
443 | ||
444 | count = head->commit - head->read; | |
e0495736 AC |
445 | if (!count) { |
446 | if (head->next == NULL) | |
447 | break; | |
5cff39c6 | 448 | buf->head = head->next; |
ecbbfd44 | 449 | tty_buffer_free(port, head); |
e0495736 AC |
450 | continue; |
451 | } | |
81de916f | 452 | if (!tty->receive_room) |
55db4c64 LT |
453 | break; |
454 | if (count > tty->receive_room) | |
455 | count = tty->receive_room; | |
e0495736 AC |
456 | char_buf = head->char_buf_ptr + head->read; |
457 | flag_buf = head->flag_buf_ptr + head->read; | |
55db4c64 | 458 | head->read += count; |
5cff39c6 | 459 | spin_unlock_irqrestore(&buf->lock, flags); |
55db4c64 | 460 | disc->ops->receive_buf(tty, char_buf, |
e0495736 | 461 | flag_buf, count); |
5cff39c6 | 462 | spin_lock_irqsave(&buf->lock, flags); |
39f610e4 PH |
463 | /* Ldisc or user is trying to flush the buffers. |
464 | We may have a deferred request to flush the | |
465 | input buffer, if so pull the chain under the lock | |
466 | and empty the queue */ | |
467 | if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) { | |
468 | __tty_buffer_flush(port); | |
469 | clear_bit(TTYP_FLUSHPENDING, &port->iflags); | |
470 | wake_up(&tty->read_wait); | |
471 | break; | |
472 | } | |
e0495736 | 473 | } |
2fc20661 | 474 | clear_bit(TTYP_FLUSHING, &port->iflags); |
e0495736 | 475 | } |
45242006 | 476 | |
5cff39c6 | 477 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
478 | |
479 | tty_ldisc_deref(disc); | |
480 | } | |
481 | ||
e043e42b OH |
482 | /** |
483 | * tty_flush_to_ldisc | |
484 | * @tty: tty to push | |
485 | * | |
486 | * Push the terminal flip buffers to the line discipline. | |
487 | * | |
488 | * Must not be called from IRQ context. | |
489 | */ | |
490 | void tty_flush_to_ldisc(struct tty_struct *tty) | |
491 | { | |
d6c53c0e | 492 | if (!tty->port->low_latency) |
ecbbfd44 | 493 | flush_work(&tty->port->buf.work); |
e043e42b OH |
494 | } |
495 | ||
e0495736 AC |
496 | /** |
497 | * tty_flip_buffer_push - terminal | |
2e124b4a | 498 | * @port: tty port to push |
e0495736 AC |
499 | * |
500 | * Queue a push of the terminal flip buffers to the line discipline. This | |
d6c53c0e JS |
501 | * function must not be called from IRQ context if port->low_latency is |
502 | * set. | |
e0495736 AC |
503 | * |
504 | * In the event of the queue being busy for flipping the work will be | |
505 | * held off and retried later. | |
506 | * | |
507 | * Locking: tty buffer lock. Driver locks in low latency mode. | |
508 | */ | |
509 | ||
2e124b4a | 510 | void tty_flip_buffer_push(struct tty_port *port) |
e0495736 | 511 | { |
2e124b4a | 512 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 513 | unsigned long flags; |
5cff39c6 JS |
514 | |
515 | spin_lock_irqsave(&buf->lock, flags); | |
516 | if (buf->tail != NULL) | |
517 | buf->tail->commit = buf->tail->used; | |
518 | spin_unlock_irqrestore(&buf->lock, flags); | |
e0495736 | 519 | |
2e124b4a | 520 | if (port->low_latency) |
5cff39c6 | 521 | flush_to_ldisc(&buf->work); |
e0495736 | 522 | else |
5cff39c6 | 523 | schedule_work(&buf->work); |
e0495736 AC |
524 | } |
525 | EXPORT_SYMBOL(tty_flip_buffer_push); | |
526 | ||
527 | /** | |
528 | * tty_buffer_init - prepare a tty buffer structure | |
529 | * @tty: tty to initialise | |
530 | * | |
531 | * Set up the initial state of the buffer management for a tty device. | |
532 | * Must be called before the other tty buffer functions are used. | |
533 | * | |
534 | * Locking: none | |
535 | */ | |
536 | ||
ecbbfd44 | 537 | void tty_buffer_init(struct tty_port *port) |
e0495736 | 538 | { |
ecbbfd44 | 539 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 JS |
540 | |
541 | spin_lock_init(&buf->lock); | |
542 | buf->head = NULL; | |
543 | buf->tail = NULL; | |
544 | buf->free = NULL; | |
545 | buf->memory_used = 0; | |
546 | INIT_WORK(&buf->work, flush_to_ldisc); | |
e0495736 AC |
547 | } |
548 |