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 | 20 | |
1cef50e3 PH |
21 | |
22 | #define MIN_TTYB_SIZE 256 | |
23 | #define TTYB_ALIGN_MASK 255 | |
24 | ||
9dd5139f PH |
25 | static void tty_buffer_reset(struct tty_buffer *p, size_t size) |
26 | { | |
27 | p->used = 0; | |
28 | p->size = size; | |
29 | p->next = NULL; | |
30 | p->commit = 0; | |
31 | p->read = 0; | |
32 | } | |
33 | ||
e0495736 AC |
34 | /** |
35 | * tty_buffer_free_all - free buffers used by a tty | |
36 | * @tty: tty to free from | |
37 | * | |
38 | * Remove all the buffers pending on a tty whether queued with data | |
39 | * or in the free ring. Must be called when the tty is no longer in use | |
40 | * | |
41 | * Locking: none | |
42 | */ | |
43 | ||
ecbbfd44 | 44 | void tty_buffer_free_all(struct tty_port *port) |
e0495736 | 45 | { |
ecbbfd44 | 46 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 47 | struct tty_buffer *thead; |
5cff39c6 JS |
48 | |
49 | while ((thead = buf->head) != NULL) { | |
50 | buf->head = thead->next; | |
e0495736 AC |
51 | kfree(thead); |
52 | } | |
5cff39c6 JS |
53 | while ((thead = buf->free) != NULL) { |
54 | buf->free = thead->next; | |
e0495736 AC |
55 | kfree(thead); |
56 | } | |
5cff39c6 JS |
57 | buf->tail = NULL; |
58 | buf->memory_used = 0; | |
e0495736 AC |
59 | } |
60 | ||
61 | /** | |
62 | * tty_buffer_alloc - allocate a tty buffer | |
63 | * @tty: tty device | |
64 | * @size: desired size (characters) | |
65 | * | |
66 | * Allocate a new tty buffer to hold the desired number of characters. | |
11b9faa4 PH |
67 | * We round our buffers off in 256 character chunks to get better |
68 | * allocation behaviour. | |
e0495736 AC |
69 | * Return NULL if out of memory or the allocation would exceed the |
70 | * per device queue | |
71 | * | |
72 | * Locking: Caller must hold tty->buf.lock | |
73 | */ | |
74 | ||
ecbbfd44 | 75 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
e0495736 | 76 | { |
11b9faa4 | 77 | struct tty_buffer **tbh = &port->buf.free; |
e0495736 AC |
78 | struct tty_buffer *p; |
79 | ||
11b9faa4 PH |
80 | /* Round the buffer size out */ |
81 | size = __ALIGN_MASK(size, TTYB_ALIGN_MASK); | |
82 | ||
83 | if (size <= MIN_TTYB_SIZE) { | |
84 | if (*tbh) { | |
85 | p = *tbh; | |
86 | *tbh = p->next; | |
87 | goto found; | |
88 | } | |
89 | } | |
90 | ||
91 | /* Should possibly check if this fails for the largest buffer we | |
92 | have queued and recycle that ? */ | |
ecbbfd44 | 93 | if (port->buf.memory_used + size > 65536) |
e0495736 AC |
94 | return NULL; |
95 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); | |
96 | if (p == NULL) | |
97 | return NULL; | |
9dd5139f | 98 | |
11b9faa4 | 99 | found: |
9dd5139f | 100 | tty_buffer_reset(p, size); |
ecbbfd44 | 101 | port->buf.memory_used += size; |
e0495736 AC |
102 | return p; |
103 | } | |
104 | ||
105 | /** | |
106 | * tty_buffer_free - free a tty buffer | |
107 | * @tty: tty owning the buffer | |
108 | * @b: the buffer to free | |
109 | * | |
110 | * Free a tty buffer, or add it to the free list according to our | |
111 | * internal strategy | |
112 | * | |
113 | * Locking: Caller must hold tty->buf.lock | |
114 | */ | |
115 | ||
ecbbfd44 | 116 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 117 | { |
ecbbfd44 | 118 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 119 | |
e0495736 | 120 | /* Dumb strategy for now - should keep some stats */ |
5cff39c6 JS |
121 | buf->memory_used -= b->size; |
122 | WARN_ON(buf->memory_used < 0); | |
e0495736 | 123 | |
1cef50e3 | 124 | if (b->size > MIN_TTYB_SIZE) |
e0495736 AC |
125 | kfree(b); |
126 | else { | |
5cff39c6 JS |
127 | b->next = buf->free; |
128 | buf->free = b; | |
e0495736 AC |
129 | } |
130 | } | |
131 | ||
132 | /** | |
133 | * __tty_buffer_flush - flush full tty buffers | |
134 | * @tty: tty to flush | |
135 | * | |
136 | * flush all the buffers containing receive data. Caller must | |
137 | * hold the buffer lock and must have ensured no parallel flush to | |
138 | * ldisc is running. | |
139 | * | |
140 | * Locking: Caller must hold tty->buf.lock | |
141 | */ | |
142 | ||
ecbbfd44 | 143 | static void __tty_buffer_flush(struct tty_port *port) |
e0495736 | 144 | { |
ecbbfd44 | 145 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
146 | struct tty_buffer *thead; |
147 | ||
64325a3b IZ |
148 | if (unlikely(buf->head == NULL)) |
149 | return; | |
150 | while ((thead = buf->head->next) != NULL) { | |
151 | tty_buffer_free(port, buf->head); | |
152 | buf->head = thead; | |
e0495736 | 153 | } |
64325a3b IZ |
154 | WARN_ON(buf->head != buf->tail); |
155 | buf->head->read = buf->head->commit; | |
e0495736 AC |
156 | } |
157 | ||
158 | /** | |
159 | * tty_buffer_flush - flush full tty buffers | |
160 | * @tty: tty to flush | |
161 | * | |
162 | * flush all the buffers containing receive data. If the buffer is | |
163 | * being processed by flush_to_ldisc then we defer the processing | |
164 | * to that function | |
165 | * | |
166 | * Locking: none | |
167 | */ | |
168 | ||
169 | void tty_buffer_flush(struct tty_struct *tty) | |
170 | { | |
2fc20661 | 171 | struct tty_port *port = tty->port; |
ecbbfd44 | 172 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 173 | unsigned long flags; |
5cff39c6 JS |
174 | |
175 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
176 | |
177 | /* If the data is being pushed to the tty layer then we can't | |
178 | process it here. Instead set a flag and the flush_to_ldisc | |
179 | path will process the flush request before it exits */ | |
2fc20661 JS |
180 | if (test_bit(TTYP_FLUSHING, &port->iflags)) { |
181 | set_bit(TTYP_FLUSHPENDING, &port->iflags); | |
5cff39c6 | 182 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 | 183 | wait_event(tty->read_wait, |
2fc20661 | 184 | test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); |
e0495736 AC |
185 | return; |
186 | } else | |
ecbbfd44 | 187 | __tty_buffer_flush(port); |
5cff39c6 | 188 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
189 | } |
190 | ||
e0495736 | 191 | /** |
64325a3b | 192 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
193 | * @tty: tty structure |
194 | * @size: size desired | |
195 | * | |
196 | * Make at least size bytes of linear space available for the tty | |
197 | * buffer. If we fail return the size we managed to find. | |
64325a3b IZ |
198 | * |
199 | * Locking: Takes port->buf.lock | |
e0495736 | 200 | */ |
64325a3b | 201 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
e0495736 | 202 | { |
ecbbfd44 | 203 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
204 | struct tty_buffer *b, *n; |
205 | int left; | |
64325a3b IZ |
206 | unsigned long flags; |
207 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
208 | /* OPTIMISATION: We could keep a per tty "zero" sized buffer to |
209 | remove this conditional if its worth it. This would be invisible | |
210 | to the callers */ | |
5cff39c6 JS |
211 | b = buf->tail; |
212 | if (b != NULL) | |
e0495736 AC |
213 | left = b->size - b->used; |
214 | else | |
215 | left = 0; | |
216 | ||
217 | if (left < size) { | |
218 | /* This is the slow path - looking for new buffers to use */ | |
11b9faa4 | 219 | if ((n = tty_buffer_alloc(port, size)) != NULL) { |
e0495736 AC |
220 | if (b != NULL) { |
221 | b->next = n; | |
222 | b->commit = b->used; | |
223 | } else | |
5cff39c6 JS |
224 | buf->head = n; |
225 | buf->tail = n; | |
e0495736 AC |
226 | } else |
227 | size = left; | |
228 | } | |
64325a3b | 229 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
230 | return size; |
231 | } | |
232 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); | |
233 | ||
234 | /** | |
2832fc11 | 235 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 236 | * @port: tty port |
e0495736 | 237 | * @chars: characters |
2832fc11 | 238 | * @flag: flag value for each character |
e0495736 AC |
239 | * @size: size |
240 | * | |
241 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 242 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 | 243 | * |
ecbbfd44 | 244 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
245 | */ |
246 | ||
2f693357 | 247 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 248 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
249 | { |
250 | int copied = 0; | |
251 | do { | |
d4bee0a6 | 252 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
253 | int space = tty_buffer_request_room(port, goal); |
254 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 255 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 256 | if (unlikely(space == 0)) { |
e0495736 | 257 | break; |
c56a00a1 | 258 | } |
1fc359fc PH |
259 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
260 | memset(flag_buf_ptr(tb, tb->used), flag, space); | |
e0495736 AC |
261 | tb->used += space; |
262 | copied += space; | |
263 | chars += space; | |
264 | /* There is a small chance that we need to split the data over | |
265 | several buffers. If this is the case we must loop */ | |
266 | } while (unlikely(size > copied)); | |
267 | return copied; | |
268 | } | |
2832fc11 | 269 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
270 | |
271 | /** | |
272 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 273 | * @port: tty port |
e0495736 AC |
274 | * @chars: characters |
275 | * @flags: flag bytes | |
276 | * @size: size | |
277 | * | |
278 | * Queue a series of bytes to the tty buffering. For each character | |
279 | * the flags array indicates the status of the character. Returns the | |
280 | * number added. | |
281 | * | |
ecbbfd44 | 282 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
283 | */ |
284 | ||
2f693357 | 285 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
286 | const unsigned char *chars, const char *flags, size_t size) |
287 | { | |
288 | int copied = 0; | |
289 | do { | |
d4bee0a6 | 290 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
291 | int space = tty_buffer_request_room(port, goal); |
292 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 293 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 294 | if (unlikely(space == 0)) { |
e0495736 | 295 | break; |
c56a00a1 | 296 | } |
1fc359fc PH |
297 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
298 | memcpy(flag_buf_ptr(tb, tb->used), flags, space); | |
e0495736 AC |
299 | tb->used += space; |
300 | copied += space; | |
301 | chars += space; | |
302 | flags += space; | |
303 | /* There is a small chance that we need to split the data over | |
304 | several buffers. If this is the case we must loop */ | |
305 | } while (unlikely(size > copied)); | |
306 | return copied; | |
307 | } | |
308 | EXPORT_SYMBOL(tty_insert_flip_string_flags); | |
309 | ||
310 | /** | |
311 | * tty_schedule_flip - push characters to ldisc | |
6732c8bb | 312 | * @port: tty port to push from |
e0495736 AC |
313 | * |
314 | * Takes any pending buffers and transfers their ownership to the | |
315 | * ldisc side of the queue. It then schedules those characters for | |
316 | * processing by the line discipline. | |
cee4ad1e IS |
317 | * Note that this function can only be used when the low_latency flag |
318 | * is unset. Otherwise the workqueue won't be flushed. | |
e0495736 | 319 | * |
ecbbfd44 | 320 | * Locking: Takes port->buf.lock |
e0495736 AC |
321 | */ |
322 | ||
6732c8bb | 323 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 324 | { |
6732c8bb | 325 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 326 | unsigned long flags; |
6732c8bb | 327 | WARN_ON(port->low_latency); |
5cff39c6 JS |
328 | |
329 | spin_lock_irqsave(&buf->lock, flags); | |
330 | if (buf->tail != NULL) | |
331 | buf->tail->commit = buf->tail->used; | |
332 | spin_unlock_irqrestore(&buf->lock, flags); | |
333 | schedule_work(&buf->work); | |
e0495736 AC |
334 | } |
335 | EXPORT_SYMBOL(tty_schedule_flip); | |
336 | ||
337 | /** | |
338 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 339 | * @port: tty port |
e0495736 AC |
340 | * @chars: return pointer for character write area |
341 | * @size: desired size | |
342 | * | |
343 | * Prepare a block of space in the buffer for data. Returns the length | |
344 | * available and buffer pointer to the space which is now allocated and | |
345 | * accounted for as ready for normal characters. This is used for drivers | |
346 | * that need their own block copy routines into the buffer. There is no | |
347 | * guarantee the buffer is a DMA target! | |
348 | * | |
ecbbfd44 | 349 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
350 | */ |
351 | ||
2f693357 | 352 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 353 | size_t size) |
e0495736 | 354 | { |
64325a3b | 355 | int space = tty_buffer_request_room(port, size); |
e0495736 | 356 | if (likely(space)) { |
64325a3b | 357 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
358 | *chars = char_buf_ptr(tb, tb->used); |
359 | memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space); | |
e0495736 AC |
360 | tb->used += space; |
361 | } | |
362 | return space; | |
363 | } | |
364 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
365 | ||
366 | /** | |
367 | * tty_prepare_flip_string_flags - make room for characters | |
2f693357 | 368 | * @port: tty port |
e0495736 AC |
369 | * @chars: return pointer for character write area |
370 | * @flags: return pointer for status flag write area | |
371 | * @size: desired size | |
372 | * | |
373 | * Prepare a block of space in the buffer for data. Returns the length | |
374 | * available and buffer pointer to the space which is now allocated and | |
375 | * accounted for as ready for characters. This is used for drivers | |
376 | * that need their own block copy routines into the buffer. There is no | |
377 | * guarantee the buffer is a DMA target! | |
378 | * | |
ecbbfd44 | 379 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
380 | */ |
381 | ||
2f693357 | 382 | int tty_prepare_flip_string_flags(struct tty_port *port, |
e0495736 AC |
383 | unsigned char **chars, char **flags, size_t size) |
384 | { | |
64325a3b | 385 | int space = tty_buffer_request_room(port, size); |
e0495736 | 386 | if (likely(space)) { |
64325a3b | 387 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
388 | *chars = char_buf_ptr(tb, tb->used); |
389 | *flags = flag_buf_ptr(tb, tb->used); | |
e0495736 AC |
390 | tb->used += space; |
391 | } | |
392 | return space; | |
393 | } | |
394 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); | |
395 | ||
396 | ||
da261e7f PH |
397 | static int |
398 | receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) | |
399 | { | |
400 | struct tty_ldisc *disc = tty->ldisc; | |
1fc359fc PH |
401 | unsigned char *p = char_buf_ptr(head, head->read); |
402 | char *f = flag_buf_ptr(head, head->read); | |
da261e7f | 403 | |
24a89d1c PH |
404 | if (disc->ops->receive_buf2) |
405 | count = disc->ops->receive_buf2(tty, p, f, count); | |
406 | else { | |
407 | count = min_t(int, count, tty->receive_room); | |
408 | if (count) | |
409 | disc->ops->receive_buf(tty, p, f, count); | |
410 | } | |
da261e7f PH |
411 | head->read += count; |
412 | return count; | |
413 | } | |
e0495736 AC |
414 | |
415 | /** | |
416 | * flush_to_ldisc | |
417 | * @work: tty structure passed from work queue. | |
418 | * | |
419 | * This routine is called out of the software interrupt to flush data | |
420 | * from the buffer chain to the line discipline. | |
421 | * | |
422 | * Locking: holds tty->buf.lock to guard buffer list. Drops the lock | |
423 | * while invoking the line discipline receive_buf method. The | |
424 | * receive_buf method is single threaded for each tty instance. | |
425 | */ | |
426 | ||
427 | static void flush_to_ldisc(struct work_struct *work) | |
428 | { | |
ecbbfd44 JS |
429 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
430 | struct tty_bufhead *buf = &port->buf; | |
431 | struct tty_struct *tty; | |
e0495736 AC |
432 | unsigned long flags; |
433 | struct tty_ldisc *disc; | |
e0495736 | 434 | |
ecbbfd44 | 435 | tty = port->itty; |
34dcfb84 | 436 | if (tty == NULL) |
ecbbfd44 JS |
437 | return; |
438 | ||
e0495736 | 439 | disc = tty_ldisc_ref(tty); |
36697529 | 440 | if (disc == NULL) |
e0495736 AC |
441 | return; |
442 | ||
5cff39c6 | 443 | spin_lock_irqsave(&buf->lock, flags); |
45242006 | 444 | |
2fc20661 | 445 | if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { |
81de916f | 446 | struct tty_buffer *head; |
5cff39c6 | 447 | while ((head = buf->head) != NULL) { |
45242006 | 448 | int count; |
45242006 LT |
449 | |
450 | count = head->commit - head->read; | |
e0495736 AC |
451 | if (!count) { |
452 | if (head->next == NULL) | |
453 | break; | |
5cff39c6 | 454 | buf->head = head->next; |
ecbbfd44 | 455 | tty_buffer_free(port, head); |
e0495736 AC |
456 | continue; |
457 | } | |
5cff39c6 | 458 | spin_unlock_irqrestore(&buf->lock, flags); |
da261e7f PH |
459 | |
460 | count = receive_buf(tty, head, count); | |
461 | ||
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; | |
da261e7f PH |
472 | } else if (!count) |
473 | break; | |
e0495736 | 474 | } |
2fc20661 | 475 | clear_bit(TTYP_FLUSHING, &port->iflags); |
e0495736 | 476 | } |
45242006 | 477 | |
5cff39c6 | 478 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
479 | |
480 | tty_ldisc_deref(disc); | |
481 | } | |
482 | ||
e043e42b OH |
483 | /** |
484 | * tty_flush_to_ldisc | |
485 | * @tty: tty to push | |
486 | * | |
487 | * Push the terminal flip buffers to the line discipline. | |
488 | * | |
489 | * Must not be called from IRQ context. | |
490 | */ | |
491 | void tty_flush_to_ldisc(struct tty_struct *tty) | |
492 | { | |
d6c53c0e | 493 | if (!tty->port->low_latency) |
ecbbfd44 | 494 | flush_work(&tty->port->buf.work); |
e043e42b OH |
495 | } |
496 | ||
e0495736 AC |
497 | /** |
498 | * tty_flip_buffer_push - terminal | |
2e124b4a | 499 | * @port: tty port to push |
e0495736 AC |
500 | * |
501 | * Queue a push of the terminal flip buffers to the line discipline. This | |
d6c53c0e JS |
502 | * function must not be called from IRQ context if port->low_latency is |
503 | * set. | |
e0495736 AC |
504 | * |
505 | * In the event of the queue being busy for flipping the work will be | |
506 | * held off and retried later. | |
507 | * | |
508 | * Locking: tty buffer lock. Driver locks in low latency mode. | |
509 | */ | |
510 | ||
2e124b4a | 511 | void tty_flip_buffer_push(struct tty_port *port) |
e0495736 | 512 | { |
2e124b4a | 513 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 514 | unsigned long flags; |
5cff39c6 JS |
515 | |
516 | spin_lock_irqsave(&buf->lock, flags); | |
517 | if (buf->tail != NULL) | |
518 | buf->tail->commit = buf->tail->used; | |
519 | spin_unlock_irqrestore(&buf->lock, flags); | |
e0495736 | 520 | |
2e124b4a | 521 | if (port->low_latency) |
5cff39c6 | 522 | flush_to_ldisc(&buf->work); |
e0495736 | 523 | else |
5cff39c6 | 524 | schedule_work(&buf->work); |
e0495736 AC |
525 | } |
526 | EXPORT_SYMBOL(tty_flip_buffer_push); | |
527 | ||
528 | /** | |
529 | * tty_buffer_init - prepare a tty buffer structure | |
530 | * @tty: tty to initialise | |
531 | * | |
532 | * Set up the initial state of the buffer management for a tty device. | |
533 | * Must be called before the other tty buffer functions are used. | |
534 | * | |
535 | * Locking: none | |
536 | */ | |
537 | ||
ecbbfd44 | 538 | void tty_buffer_init(struct tty_port *port) |
e0495736 | 539 | { |
ecbbfd44 | 540 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 JS |
541 | |
542 | spin_lock_init(&buf->lock); | |
543 | buf->head = NULL; | |
544 | buf->tail = NULL; | |
545 | buf->free = NULL; | |
546 | buf->memory_used = 0; | |
547 | INIT_WORK(&buf->work, flush_to_ldisc); | |
e0495736 AC |
548 | } |
549 |