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> | |
19 | ||
20 | /** | |
21 | * tty_buffer_free_all - free buffers used by a tty | |
22 | * @tty: tty to free from | |
23 | * | |
24 | * Remove all the buffers pending on a tty whether queued with data | |
25 | * or in the free ring. Must be called when the tty is no longer in use | |
26 | * | |
27 | * Locking: none | |
28 | */ | |
29 | ||
ecbbfd44 | 30 | void tty_buffer_free_all(struct tty_port *port) |
e0495736 | 31 | { |
ecbbfd44 | 32 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 33 | struct tty_buffer *thead; |
5cff39c6 JS |
34 | |
35 | while ((thead = buf->head) != NULL) { | |
36 | buf->head = thead->next; | |
e0495736 AC |
37 | kfree(thead); |
38 | } | |
5cff39c6 JS |
39 | while ((thead = buf->free) != NULL) { |
40 | buf->free = thead->next; | |
e0495736 AC |
41 | kfree(thead); |
42 | } | |
5cff39c6 JS |
43 | buf->tail = NULL; |
44 | buf->memory_used = 0; | |
e0495736 AC |
45 | } |
46 | ||
47 | /** | |
48 | * tty_buffer_alloc - allocate a tty buffer | |
49 | * @tty: tty device | |
50 | * @size: desired size (characters) | |
51 | * | |
52 | * Allocate a new tty buffer to hold the desired number of characters. | |
53 | * Return NULL if out of memory or the allocation would exceed the | |
54 | * per device queue | |
55 | * | |
56 | * Locking: Caller must hold tty->buf.lock | |
57 | */ | |
58 | ||
ecbbfd44 | 59 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
e0495736 AC |
60 | { |
61 | struct tty_buffer *p; | |
62 | ||
ecbbfd44 | 63 | if (port->buf.memory_used + size > 65536) |
e0495736 AC |
64 | return NULL; |
65 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); | |
66 | if (p == NULL) | |
67 | return NULL; | |
68 | p->used = 0; | |
69 | p->size = size; | |
70 | p->next = NULL; | |
71 | p->commit = 0; | |
72 | p->read = 0; | |
73 | p->char_buf_ptr = (char *)(p->data); | |
74 | p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size; | |
ecbbfd44 | 75 | port->buf.memory_used += size; |
e0495736 AC |
76 | return p; |
77 | } | |
78 | ||
79 | /** | |
80 | * tty_buffer_free - free a tty buffer | |
81 | * @tty: tty owning the buffer | |
82 | * @b: the buffer to free | |
83 | * | |
84 | * Free a tty buffer, or add it to the free list according to our | |
85 | * internal strategy | |
86 | * | |
87 | * Locking: Caller must hold tty->buf.lock | |
88 | */ | |
89 | ||
ecbbfd44 | 90 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 91 | { |
ecbbfd44 | 92 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 93 | |
e0495736 | 94 | /* Dumb strategy for now - should keep some stats */ |
5cff39c6 JS |
95 | buf->memory_used -= b->size; |
96 | WARN_ON(buf->memory_used < 0); | |
e0495736 AC |
97 | |
98 | if (b->size >= 512) | |
99 | kfree(b); | |
100 | else { | |
5cff39c6 JS |
101 | b->next = buf->free; |
102 | buf->free = b; | |
e0495736 AC |
103 | } |
104 | } | |
105 | ||
106 | /** | |
107 | * __tty_buffer_flush - flush full tty buffers | |
108 | * @tty: tty to flush | |
109 | * | |
110 | * flush all the buffers containing receive data. Caller must | |
111 | * hold the buffer lock and must have ensured no parallel flush to | |
112 | * ldisc is running. | |
113 | * | |
114 | * Locking: Caller must hold tty->buf.lock | |
115 | */ | |
116 | ||
ecbbfd44 | 117 | static void __tty_buffer_flush(struct tty_port *port) |
e0495736 | 118 | { |
ecbbfd44 | 119 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
120 | struct tty_buffer *thead; |
121 | ||
64325a3b IZ |
122 | if (unlikely(buf->head == NULL)) |
123 | return; | |
124 | while ((thead = buf->head->next) != NULL) { | |
125 | tty_buffer_free(port, buf->head); | |
126 | buf->head = thead; | |
e0495736 | 127 | } |
64325a3b IZ |
128 | WARN_ON(buf->head != buf->tail); |
129 | buf->head->read = buf->head->commit; | |
e0495736 AC |
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. If the buffer is | |
137 | * being processed by flush_to_ldisc then we defer the processing | |
138 | * to that function | |
139 | * | |
140 | * Locking: none | |
141 | */ | |
142 | ||
143 | void tty_buffer_flush(struct tty_struct *tty) | |
144 | { | |
2fc20661 | 145 | struct tty_port *port = tty->port; |
ecbbfd44 | 146 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 147 | unsigned long flags; |
5cff39c6 JS |
148 | |
149 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
150 | |
151 | /* If the data is being pushed to the tty layer then we can't | |
152 | process it here. Instead set a flag and the flush_to_ldisc | |
153 | path will process the flush request before it exits */ | |
2fc20661 JS |
154 | if (test_bit(TTYP_FLUSHING, &port->iflags)) { |
155 | set_bit(TTYP_FLUSHPENDING, &port->iflags); | |
5cff39c6 | 156 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 | 157 | wait_event(tty->read_wait, |
2fc20661 | 158 | test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); |
e0495736 AC |
159 | return; |
160 | } else | |
ecbbfd44 | 161 | __tty_buffer_flush(port); |
5cff39c6 | 162 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
163 | } |
164 | ||
165 | /** | |
166 | * tty_buffer_find - find a free tty buffer | |
167 | * @tty: tty owning the buffer | |
168 | * @size: characters wanted | |
169 | * | |
170 | * Locate an existing suitable tty buffer or if we are lacking one then | |
171 | * allocate a new one. We round our buffers off in 256 character chunks | |
172 | * to get better allocation behaviour. | |
173 | * | |
174 | * Locking: Caller must hold tty->buf.lock | |
175 | */ | |
176 | ||
ecbbfd44 | 177 | static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size) |
e0495736 | 178 | { |
ecbbfd44 | 179 | struct tty_buffer **tbh = &port->buf.free; |
e0495736 AC |
180 | while ((*tbh) != NULL) { |
181 | struct tty_buffer *t = *tbh; | |
182 | if (t->size >= size) { | |
183 | *tbh = t->next; | |
184 | t->next = NULL; | |
185 | t->used = 0; | |
186 | t->commit = 0; | |
187 | t->read = 0; | |
ecbbfd44 | 188 | port->buf.memory_used += t->size; |
e0495736 AC |
189 | return t; |
190 | } | |
191 | tbh = &((*tbh)->next); | |
192 | } | |
193 | /* Round the buffer size out */ | |
194 | size = (size + 0xFF) & ~0xFF; | |
ecbbfd44 | 195 | return tty_buffer_alloc(port, size); |
e0495736 AC |
196 | /* Should possibly check if this fails for the largest buffer we |
197 | have queued and recycle that ? */ | |
198 | } | |
e0495736 | 199 | /** |
64325a3b | 200 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
201 | * @tty: tty structure |
202 | * @size: size desired | |
203 | * | |
204 | * Make at least size bytes of linear space available for the tty | |
205 | * buffer. If we fail return the size we managed to find. | |
64325a3b IZ |
206 | * |
207 | * Locking: Takes port->buf.lock | |
e0495736 | 208 | */ |
64325a3b | 209 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
e0495736 | 210 | { |
ecbbfd44 | 211 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
212 | struct tty_buffer *b, *n; |
213 | int left; | |
64325a3b IZ |
214 | unsigned long flags; |
215 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
216 | /* OPTIMISATION: We could keep a per tty "zero" sized buffer to |
217 | remove this conditional if its worth it. This would be invisible | |
218 | to the callers */ | |
5cff39c6 JS |
219 | b = buf->tail; |
220 | if (b != NULL) | |
e0495736 AC |
221 | left = b->size - b->used; |
222 | else | |
223 | left = 0; | |
224 | ||
225 | if (left < size) { | |
226 | /* This is the slow path - looking for new buffers to use */ | |
ecbbfd44 | 227 | if ((n = tty_buffer_find(port, size)) != NULL) { |
e0495736 AC |
228 | if (b != NULL) { |
229 | b->next = n; | |
230 | b->commit = b->used; | |
231 | } else | |
5cff39c6 JS |
232 | buf->head = n; |
233 | buf->tail = n; | |
e0495736 AC |
234 | } else |
235 | size = left; | |
236 | } | |
64325a3b | 237 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
238 | return size; |
239 | } | |
240 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); | |
241 | ||
242 | /** | |
2832fc11 | 243 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 244 | * @port: tty port |
e0495736 | 245 | * @chars: characters |
2832fc11 | 246 | * @flag: flag value for each character |
e0495736 AC |
247 | * @size: size |
248 | * | |
249 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 250 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 | 251 | * |
ecbbfd44 | 252 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
253 | */ |
254 | ||
2f693357 | 255 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 256 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
257 | { |
258 | int copied = 0; | |
259 | do { | |
d4bee0a6 | 260 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
261 | int space = tty_buffer_request_room(port, goal); |
262 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 263 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 264 | if (unlikely(space == 0)) { |
e0495736 | 265 | break; |
c56a00a1 | 266 | } |
e0495736 | 267 | memcpy(tb->char_buf_ptr + tb->used, chars, space); |
2832fc11 | 268 | memset(tb->flag_buf_ptr + tb->used, flag, space); |
e0495736 AC |
269 | tb->used += space; |
270 | copied += space; | |
271 | chars += space; | |
272 | /* There is a small chance that we need to split the data over | |
273 | several buffers. If this is the case we must loop */ | |
274 | } while (unlikely(size > copied)); | |
275 | return copied; | |
276 | } | |
2832fc11 | 277 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
278 | |
279 | /** | |
280 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 281 | * @port: tty port |
e0495736 AC |
282 | * @chars: characters |
283 | * @flags: flag bytes | |
284 | * @size: size | |
285 | * | |
286 | * Queue a series of bytes to the tty buffering. For each character | |
287 | * the flags array indicates the status of the character. Returns the | |
288 | * number added. | |
289 | * | |
ecbbfd44 | 290 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
291 | */ |
292 | ||
2f693357 | 293 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
294 | const unsigned char *chars, const char *flags, size_t size) |
295 | { | |
296 | int copied = 0; | |
297 | do { | |
d4bee0a6 | 298 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
299 | int space = tty_buffer_request_room(port, goal); |
300 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 301 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 302 | if (unlikely(space == 0)) { |
e0495736 | 303 | break; |
c56a00a1 | 304 | } |
e0495736 AC |
305 | memcpy(tb->char_buf_ptr + tb->used, chars, space); |
306 | memcpy(tb->flag_buf_ptr + tb->used, flags, space); | |
307 | tb->used += space; | |
308 | copied += space; | |
309 | chars += space; | |
310 | flags += space; | |
311 | /* There is a small chance that we need to split the data over | |
312 | several buffers. If this is the case we must loop */ | |
313 | } while (unlikely(size > copied)); | |
314 | return copied; | |
315 | } | |
316 | EXPORT_SYMBOL(tty_insert_flip_string_flags); | |
317 | ||
318 | /** | |
319 | * tty_schedule_flip - push characters to ldisc | |
6732c8bb | 320 | * @port: tty port to push from |
e0495736 AC |
321 | * |
322 | * Takes any pending buffers and transfers their ownership to the | |
323 | * ldisc side of the queue. It then schedules those characters for | |
324 | * processing by the line discipline. | |
cee4ad1e IS |
325 | * Note that this function can only be used when the low_latency flag |
326 | * is unset. Otherwise the workqueue won't be flushed. | |
e0495736 | 327 | * |
ecbbfd44 | 328 | * Locking: Takes port->buf.lock |
e0495736 AC |
329 | */ |
330 | ||
6732c8bb | 331 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 332 | { |
6732c8bb | 333 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 334 | unsigned long flags; |
6732c8bb | 335 | WARN_ON(port->low_latency); |
5cff39c6 JS |
336 | |
337 | spin_lock_irqsave(&buf->lock, flags); | |
338 | if (buf->tail != NULL) | |
339 | buf->tail->commit = buf->tail->used; | |
340 | spin_unlock_irqrestore(&buf->lock, flags); | |
341 | schedule_work(&buf->work); | |
e0495736 AC |
342 | } |
343 | EXPORT_SYMBOL(tty_schedule_flip); | |
344 | ||
345 | /** | |
346 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 347 | * @port: tty port |
e0495736 AC |
348 | * @chars: return pointer for character write area |
349 | * @size: desired size | |
350 | * | |
351 | * Prepare a block of space in the buffer for data. Returns the length | |
352 | * available and buffer pointer to the space which is now allocated and | |
353 | * accounted for as ready for normal characters. This is used for drivers | |
354 | * that need their own block copy routines into the buffer. There is no | |
355 | * guarantee the buffer is a DMA target! | |
356 | * | |
ecbbfd44 | 357 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
358 | */ |
359 | ||
2f693357 | 360 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 361 | size_t size) |
e0495736 | 362 | { |
64325a3b | 363 | int space = tty_buffer_request_room(port, size); |
e0495736 | 364 | if (likely(space)) { |
64325a3b | 365 | struct tty_buffer *tb = port->buf.tail; |
e0495736 AC |
366 | *chars = tb->char_buf_ptr + tb->used; |
367 | memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space); | |
368 | tb->used += space; | |
369 | } | |
370 | return space; | |
371 | } | |
372 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
373 | ||
374 | /** | |
375 | * tty_prepare_flip_string_flags - make room for characters | |
2f693357 | 376 | * @port: tty port |
e0495736 AC |
377 | * @chars: return pointer for character write area |
378 | * @flags: return pointer for status flag write area | |
379 | * @size: desired size | |
380 | * | |
381 | * Prepare a block of space in the buffer for data. Returns the length | |
382 | * available and buffer pointer to the space which is now allocated and | |
383 | * accounted for as ready for characters. This is used for drivers | |
384 | * that need their own block copy routines into the buffer. There is no | |
385 | * guarantee the buffer is a DMA target! | |
386 | * | |
ecbbfd44 | 387 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
388 | */ |
389 | ||
2f693357 | 390 | int tty_prepare_flip_string_flags(struct tty_port *port, |
e0495736 AC |
391 | unsigned char **chars, char **flags, size_t size) |
392 | { | |
64325a3b | 393 | int space = tty_buffer_request_room(port, size); |
e0495736 | 394 | if (likely(space)) { |
64325a3b | 395 | struct tty_buffer *tb = port->buf.tail; |
e0495736 AC |
396 | *chars = tb->char_buf_ptr + tb->used; |
397 | *flags = tb->flag_buf_ptr + tb->used; | |
398 | tb->used += space; | |
399 | } | |
400 | return space; | |
401 | } | |
402 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); | |
403 | ||
404 | ||
405 | ||
406 | /** | |
407 | * flush_to_ldisc | |
408 | * @work: tty structure passed from work queue. | |
409 | * | |
410 | * This routine is called out of the software interrupt to flush data | |
411 | * from the buffer chain to the line discipline. | |
412 | * | |
413 | * Locking: holds tty->buf.lock to guard buffer list. Drops the lock | |
414 | * while invoking the line discipline receive_buf method. The | |
415 | * receive_buf method is single threaded for each tty instance. | |
416 | */ | |
417 | ||
418 | static void flush_to_ldisc(struct work_struct *work) | |
419 | { | |
ecbbfd44 JS |
420 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
421 | struct tty_bufhead *buf = &port->buf; | |
422 | struct tty_struct *tty; | |
e0495736 AC |
423 | unsigned long flags; |
424 | struct tty_ldisc *disc; | |
e0495736 | 425 | |
ecbbfd44 | 426 | tty = port->itty; |
cadf7486 | 427 | if (WARN_RATELIMIT(tty == NULL, "tty is NULL\n")) |
ecbbfd44 JS |
428 | return; |
429 | ||
e0495736 AC |
430 | disc = tty_ldisc_ref(tty); |
431 | if (disc == NULL) /* !TTY_LDISC */ | |
432 | return; | |
433 | ||
5cff39c6 | 434 | spin_lock_irqsave(&buf->lock, flags); |
45242006 | 435 | |
2fc20661 | 436 | if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { |
81de916f | 437 | struct tty_buffer *head; |
5cff39c6 | 438 | while ((head = buf->head) != NULL) { |
45242006 LT |
439 | int count; |
440 | char *char_buf; | |
441 | unsigned char *flag_buf; | |
442 | ||
443 | count = head->commit - head->read; | |
e0495736 AC |
444 | if (!count) { |
445 | if (head->next == NULL) | |
446 | break; | |
5cff39c6 | 447 | buf->head = head->next; |
ecbbfd44 | 448 | tty_buffer_free(port, head); |
e0495736 AC |
449 | continue; |
450 | } | |
451 | /* Ldisc or user is trying to flush the buffers | |
452 | we are feeding to the ldisc, stop feeding the | |
453 | line discipline as we want to empty the queue */ | |
2fc20661 | 454 | if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) |
e0495736 | 455 | break; |
81de916f | 456 | if (!tty->receive_room) |
55db4c64 LT |
457 | break; |
458 | if (count > tty->receive_room) | |
459 | count = tty->receive_room; | |
e0495736 AC |
460 | char_buf = head->char_buf_ptr + head->read; |
461 | flag_buf = head->flag_buf_ptr + head->read; | |
55db4c64 | 462 | head->read += count; |
5cff39c6 | 463 | spin_unlock_irqrestore(&buf->lock, flags); |
55db4c64 | 464 | disc->ops->receive_buf(tty, char_buf, |
e0495736 | 465 | flag_buf, count); |
5cff39c6 | 466 | spin_lock_irqsave(&buf->lock, flags); |
e0495736 | 467 | } |
2fc20661 | 468 | clear_bit(TTYP_FLUSHING, &port->iflags); |
e0495736 | 469 | } |
45242006 | 470 | |
e0495736 AC |
471 | /* We may have a deferred request to flush the input buffer, |
472 | if so pull the chain under the lock and empty the queue */ | |
2fc20661 | 473 | if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) { |
ecbbfd44 | 474 | __tty_buffer_flush(port); |
2fc20661 | 475 | clear_bit(TTYP_FLUSHPENDING, &port->iflags); |
e0495736 AC |
476 | wake_up(&tty->read_wait); |
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 |