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; | |
ecbbfd44 | 74 | port->buf.memory_used += size; |
e0495736 AC |
75 | return p; |
76 | } | |
77 | ||
78 | /** | |
79 | * tty_buffer_free - free a tty buffer | |
80 | * @tty: tty owning the buffer | |
81 | * @b: the buffer to free | |
82 | * | |
83 | * Free a tty buffer, or add it to the free list according to our | |
84 | * internal strategy | |
85 | * | |
86 | * Locking: Caller must hold tty->buf.lock | |
87 | */ | |
88 | ||
ecbbfd44 | 89 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 90 | { |
ecbbfd44 | 91 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 92 | |
e0495736 | 93 | /* Dumb strategy for now - should keep some stats */ |
5cff39c6 JS |
94 | buf->memory_used -= b->size; |
95 | WARN_ON(buf->memory_used < 0); | |
e0495736 AC |
96 | |
97 | if (b->size >= 512) | |
98 | kfree(b); | |
99 | else { | |
5cff39c6 JS |
100 | b->next = buf->free; |
101 | buf->free = b; | |
e0495736 AC |
102 | } |
103 | } | |
104 | ||
105 | /** | |
106 | * __tty_buffer_flush - flush full tty buffers | |
107 | * @tty: tty to flush | |
108 | * | |
109 | * flush all the buffers containing receive data. Caller must | |
110 | * hold the buffer lock and must have ensured no parallel flush to | |
111 | * ldisc is running. | |
112 | * | |
113 | * Locking: Caller must hold tty->buf.lock | |
114 | */ | |
115 | ||
ecbbfd44 | 116 | static void __tty_buffer_flush(struct tty_port *port) |
e0495736 | 117 | { |
ecbbfd44 | 118 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
119 | struct tty_buffer *thead; |
120 | ||
64325a3b IZ |
121 | if (unlikely(buf->head == NULL)) |
122 | return; | |
123 | while ((thead = buf->head->next) != NULL) { | |
124 | tty_buffer_free(port, buf->head); | |
125 | buf->head = thead; | |
e0495736 | 126 | } |
64325a3b IZ |
127 | WARN_ON(buf->head != buf->tail); |
128 | buf->head->read = buf->head->commit; | |
e0495736 AC |
129 | } |
130 | ||
131 | /** | |
132 | * tty_buffer_flush - flush full tty buffers | |
133 | * @tty: tty to flush | |
134 | * | |
135 | * flush all the buffers containing receive data. If the buffer is | |
136 | * being processed by flush_to_ldisc then we defer the processing | |
137 | * to that function | |
138 | * | |
139 | * Locking: none | |
140 | */ | |
141 | ||
142 | void tty_buffer_flush(struct tty_struct *tty) | |
143 | { | |
2fc20661 | 144 | struct tty_port *port = tty->port; |
ecbbfd44 | 145 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 146 | unsigned long flags; |
5cff39c6 JS |
147 | |
148 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
149 | |
150 | /* If the data is being pushed to the tty layer then we can't | |
151 | process it here. Instead set a flag and the flush_to_ldisc | |
152 | path will process the flush request before it exits */ | |
2fc20661 JS |
153 | if (test_bit(TTYP_FLUSHING, &port->iflags)) { |
154 | set_bit(TTYP_FLUSHPENDING, &port->iflags); | |
5cff39c6 | 155 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 | 156 | wait_event(tty->read_wait, |
2fc20661 | 157 | test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); |
e0495736 AC |
158 | return; |
159 | } else | |
ecbbfd44 | 160 | __tty_buffer_flush(port); |
5cff39c6 | 161 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
162 | } |
163 | ||
164 | /** | |
165 | * tty_buffer_find - find a free tty buffer | |
166 | * @tty: tty owning the buffer | |
167 | * @size: characters wanted | |
168 | * | |
169 | * Locate an existing suitable tty buffer or if we are lacking one then | |
170 | * allocate a new one. We round our buffers off in 256 character chunks | |
171 | * to get better allocation behaviour. | |
172 | * | |
173 | * Locking: Caller must hold tty->buf.lock | |
174 | */ | |
175 | ||
ecbbfd44 | 176 | static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size) |
e0495736 | 177 | { |
ecbbfd44 | 178 | struct tty_buffer **tbh = &port->buf.free; |
e0495736 AC |
179 | while ((*tbh) != NULL) { |
180 | struct tty_buffer *t = *tbh; | |
181 | if (t->size >= size) { | |
182 | *tbh = t->next; | |
183 | t->next = NULL; | |
184 | t->used = 0; | |
185 | t->commit = 0; | |
186 | t->read = 0; | |
ecbbfd44 | 187 | port->buf.memory_used += t->size; |
e0495736 AC |
188 | return t; |
189 | } | |
190 | tbh = &((*tbh)->next); | |
191 | } | |
192 | /* Round the buffer size out */ | |
193 | size = (size + 0xFF) & ~0xFF; | |
ecbbfd44 | 194 | return tty_buffer_alloc(port, size); |
e0495736 AC |
195 | /* Should possibly check if this fails for the largest buffer we |
196 | have queued and recycle that ? */ | |
197 | } | |
e0495736 | 198 | /** |
64325a3b | 199 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
200 | * @tty: tty structure |
201 | * @size: size desired | |
202 | * | |
203 | * Make at least size bytes of linear space available for the tty | |
204 | * buffer. If we fail return the size we managed to find. | |
64325a3b IZ |
205 | * |
206 | * Locking: Takes port->buf.lock | |
e0495736 | 207 | */ |
64325a3b | 208 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
e0495736 | 209 | { |
ecbbfd44 | 210 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
211 | struct tty_buffer *b, *n; |
212 | int left; | |
64325a3b IZ |
213 | unsigned long flags; |
214 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
215 | /* OPTIMISATION: We could keep a per tty "zero" sized buffer to |
216 | remove this conditional if its worth it. This would be invisible | |
217 | to the callers */ | |
5cff39c6 JS |
218 | b = buf->tail; |
219 | if (b != NULL) | |
e0495736 AC |
220 | left = b->size - b->used; |
221 | else | |
222 | left = 0; | |
223 | ||
224 | if (left < size) { | |
225 | /* This is the slow path - looking for new buffers to use */ | |
ecbbfd44 | 226 | if ((n = tty_buffer_find(port, size)) != NULL) { |
e0495736 AC |
227 | if (b != NULL) { |
228 | b->next = n; | |
229 | b->commit = b->used; | |
230 | } else | |
5cff39c6 JS |
231 | buf->head = n; |
232 | buf->tail = n; | |
e0495736 AC |
233 | } else |
234 | size = left; | |
235 | } | |
64325a3b | 236 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
237 | return size; |
238 | } | |
239 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); | |
240 | ||
241 | /** | |
2832fc11 | 242 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 243 | * @port: tty port |
e0495736 | 244 | * @chars: characters |
2832fc11 | 245 | * @flag: flag value for each character |
e0495736 AC |
246 | * @size: size |
247 | * | |
248 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 249 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 | 250 | * |
ecbbfd44 | 251 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
252 | */ |
253 | ||
2f693357 | 254 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 255 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
256 | { |
257 | int copied = 0; | |
258 | do { | |
d4bee0a6 | 259 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
260 | int space = tty_buffer_request_room(port, goal); |
261 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 262 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 263 | if (unlikely(space == 0)) { |
e0495736 | 264 | break; |
c56a00a1 | 265 | } |
1fc359fc PH |
266 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
267 | memset(flag_buf_ptr(tb, tb->used), flag, space); | |
e0495736 AC |
268 | tb->used += space; |
269 | copied += space; | |
270 | chars += space; | |
271 | /* There is a small chance that we need to split the data over | |
272 | several buffers. If this is the case we must loop */ | |
273 | } while (unlikely(size > copied)); | |
274 | return copied; | |
275 | } | |
2832fc11 | 276 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
277 | |
278 | /** | |
279 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 280 | * @port: tty port |
e0495736 AC |
281 | * @chars: characters |
282 | * @flags: flag bytes | |
283 | * @size: size | |
284 | * | |
285 | * Queue a series of bytes to the tty buffering. For each character | |
286 | * the flags array indicates the status of the character. Returns the | |
287 | * number added. | |
288 | * | |
ecbbfd44 | 289 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
290 | */ |
291 | ||
2f693357 | 292 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
293 | const unsigned char *chars, const char *flags, size_t size) |
294 | { | |
295 | int copied = 0; | |
296 | do { | |
d4bee0a6 | 297 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
298 | int space = tty_buffer_request_room(port, goal); |
299 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 300 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 301 | if (unlikely(space == 0)) { |
e0495736 | 302 | break; |
c56a00a1 | 303 | } |
1fc359fc PH |
304 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
305 | memcpy(flag_buf_ptr(tb, tb->used), flags, space); | |
e0495736 AC |
306 | tb->used += space; |
307 | copied += space; | |
308 | chars += space; | |
309 | flags += space; | |
310 | /* There is a small chance that we need to split the data over | |
311 | several buffers. If this is the case we must loop */ | |
312 | } while (unlikely(size > copied)); | |
313 | return copied; | |
314 | } | |
315 | EXPORT_SYMBOL(tty_insert_flip_string_flags); | |
316 | ||
317 | /** | |
318 | * tty_schedule_flip - push characters to ldisc | |
6732c8bb | 319 | * @port: tty port to push from |
e0495736 AC |
320 | * |
321 | * Takes any pending buffers and transfers their ownership to the | |
322 | * ldisc side of the queue. It then schedules those characters for | |
323 | * processing by the line discipline. | |
cee4ad1e IS |
324 | * Note that this function can only be used when the low_latency flag |
325 | * is unset. Otherwise the workqueue won't be flushed. | |
e0495736 | 326 | * |
ecbbfd44 | 327 | * Locking: Takes port->buf.lock |
e0495736 AC |
328 | */ |
329 | ||
6732c8bb | 330 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 331 | { |
6732c8bb | 332 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 333 | unsigned long flags; |
6732c8bb | 334 | WARN_ON(port->low_latency); |
5cff39c6 JS |
335 | |
336 | spin_lock_irqsave(&buf->lock, flags); | |
337 | if (buf->tail != NULL) | |
338 | buf->tail->commit = buf->tail->used; | |
339 | spin_unlock_irqrestore(&buf->lock, flags); | |
340 | schedule_work(&buf->work); | |
e0495736 AC |
341 | } |
342 | EXPORT_SYMBOL(tty_schedule_flip); | |
343 | ||
344 | /** | |
345 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 346 | * @port: tty port |
e0495736 AC |
347 | * @chars: return pointer for character write area |
348 | * @size: desired size | |
349 | * | |
350 | * Prepare a block of space in the buffer for data. Returns the length | |
351 | * available and buffer pointer to the space which is now allocated and | |
352 | * accounted for as ready for normal characters. This is used for drivers | |
353 | * that need their own block copy routines into the buffer. There is no | |
354 | * guarantee the buffer is a DMA target! | |
355 | * | |
ecbbfd44 | 356 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
357 | */ |
358 | ||
2f693357 | 359 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 360 | size_t size) |
e0495736 | 361 | { |
64325a3b | 362 | int space = tty_buffer_request_room(port, size); |
e0495736 | 363 | if (likely(space)) { |
64325a3b | 364 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
365 | *chars = char_buf_ptr(tb, tb->used); |
366 | memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space); | |
e0495736 AC |
367 | tb->used += space; |
368 | } | |
369 | return space; | |
370 | } | |
371 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
372 | ||
373 | /** | |
374 | * tty_prepare_flip_string_flags - make room for characters | |
2f693357 | 375 | * @port: tty port |
e0495736 AC |
376 | * @chars: return pointer for character write area |
377 | * @flags: return pointer for status flag write area | |
378 | * @size: desired size | |
379 | * | |
380 | * Prepare a block of space in the buffer for data. Returns the length | |
381 | * available and buffer pointer to the space which is now allocated and | |
382 | * accounted for as ready for characters. This is used for drivers | |
383 | * that need their own block copy routines into the buffer. There is no | |
384 | * guarantee the buffer is a DMA target! | |
385 | * | |
ecbbfd44 | 386 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
387 | */ |
388 | ||
2f693357 | 389 | int tty_prepare_flip_string_flags(struct tty_port *port, |
e0495736 AC |
390 | unsigned char **chars, char **flags, size_t size) |
391 | { | |
64325a3b | 392 | int space = tty_buffer_request_room(port, size); |
e0495736 | 393 | if (likely(space)) { |
64325a3b | 394 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
395 | *chars = char_buf_ptr(tb, tb->used); |
396 | *flags = flag_buf_ptr(tb, tb->used); | |
e0495736 AC |
397 | tb->used += space; |
398 | } | |
399 | return space; | |
400 | } | |
401 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); | |
402 | ||
403 | ||
da261e7f PH |
404 | static int |
405 | receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) | |
406 | { | |
407 | struct tty_ldisc *disc = tty->ldisc; | |
1fc359fc PH |
408 | unsigned char *p = char_buf_ptr(head, head->read); |
409 | char *f = flag_buf_ptr(head, head->read); | |
da261e7f | 410 | |
24a89d1c PH |
411 | if (disc->ops->receive_buf2) |
412 | count = disc->ops->receive_buf2(tty, p, f, count); | |
413 | else { | |
414 | count = min_t(int, count, tty->receive_room); | |
415 | if (count) | |
416 | disc->ops->receive_buf(tty, p, f, count); | |
417 | } | |
da261e7f PH |
418 | head->read += count; |
419 | return count; | |
420 | } | |
e0495736 AC |
421 | |
422 | /** | |
423 | * flush_to_ldisc | |
424 | * @work: tty structure passed from work queue. | |
425 | * | |
426 | * This routine is called out of the software interrupt to flush data | |
427 | * from the buffer chain to the line discipline. | |
428 | * | |
429 | * Locking: holds tty->buf.lock to guard buffer list. Drops the lock | |
430 | * while invoking the line discipline receive_buf method. The | |
431 | * receive_buf method is single threaded for each tty instance. | |
432 | */ | |
433 | ||
434 | static void flush_to_ldisc(struct work_struct *work) | |
435 | { | |
ecbbfd44 JS |
436 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
437 | struct tty_bufhead *buf = &port->buf; | |
438 | struct tty_struct *tty; | |
e0495736 AC |
439 | unsigned long flags; |
440 | struct tty_ldisc *disc; | |
e0495736 | 441 | |
ecbbfd44 | 442 | tty = port->itty; |
34dcfb84 | 443 | if (tty == NULL) |
ecbbfd44 JS |
444 | return; |
445 | ||
e0495736 | 446 | disc = tty_ldisc_ref(tty); |
36697529 | 447 | if (disc == NULL) |
e0495736 AC |
448 | return; |
449 | ||
5cff39c6 | 450 | spin_lock_irqsave(&buf->lock, flags); |
45242006 | 451 | |
2fc20661 | 452 | if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { |
81de916f | 453 | struct tty_buffer *head; |
5cff39c6 | 454 | while ((head = buf->head) != NULL) { |
45242006 | 455 | int count; |
45242006 LT |
456 | |
457 | count = head->commit - head->read; | |
e0495736 AC |
458 | if (!count) { |
459 | if (head->next == NULL) | |
460 | break; | |
5cff39c6 | 461 | buf->head = head->next; |
ecbbfd44 | 462 | tty_buffer_free(port, head); |
e0495736 AC |
463 | continue; |
464 | } | |
5cff39c6 | 465 | spin_unlock_irqrestore(&buf->lock, flags); |
da261e7f PH |
466 | |
467 | count = receive_buf(tty, head, count); | |
468 | ||
5cff39c6 | 469 | spin_lock_irqsave(&buf->lock, flags); |
39f610e4 PH |
470 | /* Ldisc or user is trying to flush the buffers. |
471 | We may have a deferred request to flush the | |
472 | input buffer, if so pull the chain under the lock | |
473 | and empty the queue */ | |
474 | if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) { | |
475 | __tty_buffer_flush(port); | |
476 | clear_bit(TTYP_FLUSHPENDING, &port->iflags); | |
477 | wake_up(&tty->read_wait); | |
478 | break; | |
da261e7f PH |
479 | } else if (!count) |
480 | break; | |
e0495736 | 481 | } |
2fc20661 | 482 | clear_bit(TTYP_FLUSHING, &port->iflags); |
e0495736 | 483 | } |
45242006 | 484 | |
5cff39c6 | 485 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
486 | |
487 | tty_ldisc_deref(disc); | |
488 | } | |
489 | ||
e043e42b OH |
490 | /** |
491 | * tty_flush_to_ldisc | |
492 | * @tty: tty to push | |
493 | * | |
494 | * Push the terminal flip buffers to the line discipline. | |
495 | * | |
496 | * Must not be called from IRQ context. | |
497 | */ | |
498 | void tty_flush_to_ldisc(struct tty_struct *tty) | |
499 | { | |
d6c53c0e | 500 | if (!tty->port->low_latency) |
ecbbfd44 | 501 | flush_work(&tty->port->buf.work); |
e043e42b OH |
502 | } |
503 | ||
e0495736 AC |
504 | /** |
505 | * tty_flip_buffer_push - terminal | |
2e124b4a | 506 | * @port: tty port to push |
e0495736 AC |
507 | * |
508 | * Queue a push of the terminal flip buffers to the line discipline. This | |
d6c53c0e JS |
509 | * function must not be called from IRQ context if port->low_latency is |
510 | * set. | |
e0495736 AC |
511 | * |
512 | * In the event of the queue being busy for flipping the work will be | |
513 | * held off and retried later. | |
514 | * | |
515 | * Locking: tty buffer lock. Driver locks in low latency mode. | |
516 | */ | |
517 | ||
2e124b4a | 518 | void tty_flip_buffer_push(struct tty_port *port) |
e0495736 | 519 | { |
2e124b4a | 520 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 521 | unsigned long flags; |
5cff39c6 JS |
522 | |
523 | spin_lock_irqsave(&buf->lock, flags); | |
524 | if (buf->tail != NULL) | |
525 | buf->tail->commit = buf->tail->used; | |
526 | spin_unlock_irqrestore(&buf->lock, flags); | |
e0495736 | 527 | |
2e124b4a | 528 | if (port->low_latency) |
5cff39c6 | 529 | flush_to_ldisc(&buf->work); |
e0495736 | 530 | else |
5cff39c6 | 531 | schedule_work(&buf->work); |
e0495736 AC |
532 | } |
533 | EXPORT_SYMBOL(tty_flip_buffer_push); | |
534 | ||
535 | /** | |
536 | * tty_buffer_init - prepare a tty buffer structure | |
537 | * @tty: tty to initialise | |
538 | * | |
539 | * Set up the initial state of the buffer management for a tty device. | |
540 | * Must be called before the other tty buffer functions are used. | |
541 | * | |
542 | * Locking: none | |
543 | */ | |
544 | ||
ecbbfd44 | 545 | void tty_buffer_init(struct tty_port *port) |
e0495736 | 546 | { |
ecbbfd44 | 547 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 JS |
548 | |
549 | spin_lock_init(&buf->lock); | |
550 | buf->head = NULL; | |
551 | buf->tail = NULL; | |
552 | buf->free = NULL; | |
553 | buf->memory_used = 0; | |
554 | INIT_WORK(&buf->work, flush_to_ldisc); | |
e0495736 AC |
555 | } |
556 |