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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 | ||
e0495736 AC |
25 | /** |
26 | * tty_buffer_free_all - free buffers used by a tty | |
27 | * @tty: tty to free from | |
28 | * | |
29 | * Remove all the buffers pending on a tty whether queued with data | |
30 | * or in the free ring. Must be called when the tty is no longer in use | |
31 | * | |
32 | * Locking: none | |
33 | */ | |
34 | ||
ecbbfd44 | 35 | void tty_buffer_free_all(struct tty_port *port) |
e0495736 | 36 | { |
ecbbfd44 | 37 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 38 | struct tty_buffer *thead; |
5cff39c6 JS |
39 | |
40 | while ((thead = buf->head) != NULL) { | |
41 | buf->head = thead->next; | |
e0495736 AC |
42 | kfree(thead); |
43 | } | |
5cff39c6 JS |
44 | while ((thead = buf->free) != NULL) { |
45 | buf->free = thead->next; | |
e0495736 AC |
46 | kfree(thead); |
47 | } | |
5cff39c6 JS |
48 | buf->tail = NULL; |
49 | buf->memory_used = 0; | |
e0495736 AC |
50 | } |
51 | ||
52 | /** | |
53 | * tty_buffer_alloc - allocate a tty buffer | |
54 | * @tty: tty device | |
55 | * @size: desired size (characters) | |
56 | * | |
57 | * Allocate a new tty buffer to hold the desired number of characters. | |
58 | * Return NULL if out of memory or the allocation would exceed the | |
59 | * per device queue | |
60 | * | |
61 | * Locking: Caller must hold tty->buf.lock | |
62 | */ | |
63 | ||
ecbbfd44 | 64 | static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) |
e0495736 AC |
65 | { |
66 | struct tty_buffer *p; | |
67 | ||
ecbbfd44 | 68 | if (port->buf.memory_used + size > 65536) |
e0495736 AC |
69 | return NULL; |
70 | p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); | |
71 | if (p == NULL) | |
72 | return NULL; | |
73 | p->used = 0; | |
74 | p->size = size; | |
75 | p->next = NULL; | |
76 | p->commit = 0; | |
77 | p->read = 0; | |
ecbbfd44 | 78 | port->buf.memory_used += size; |
e0495736 AC |
79 | return p; |
80 | } | |
81 | ||
82 | /** | |
83 | * tty_buffer_free - free a tty buffer | |
84 | * @tty: tty owning the buffer | |
85 | * @b: the buffer to free | |
86 | * | |
87 | * Free a tty buffer, or add it to the free list according to our | |
88 | * internal strategy | |
89 | * | |
90 | * Locking: Caller must hold tty->buf.lock | |
91 | */ | |
92 | ||
ecbbfd44 | 93 | static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) |
e0495736 | 94 | { |
ecbbfd44 | 95 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 | 96 | |
e0495736 | 97 | /* Dumb strategy for now - should keep some stats */ |
5cff39c6 JS |
98 | buf->memory_used -= b->size; |
99 | WARN_ON(buf->memory_used < 0); | |
e0495736 | 100 | |
1cef50e3 | 101 | if (b->size > MIN_TTYB_SIZE) |
e0495736 AC |
102 | kfree(b); |
103 | else { | |
5cff39c6 JS |
104 | b->next = buf->free; |
105 | buf->free = b; | |
e0495736 AC |
106 | } |
107 | } | |
108 | ||
109 | /** | |
110 | * __tty_buffer_flush - flush full tty buffers | |
111 | * @tty: tty to flush | |
112 | * | |
113 | * flush all the buffers containing receive data. Caller must | |
114 | * hold the buffer lock and must have ensured no parallel flush to | |
115 | * ldisc is running. | |
116 | * | |
117 | * Locking: Caller must hold tty->buf.lock | |
118 | */ | |
119 | ||
ecbbfd44 | 120 | static void __tty_buffer_flush(struct tty_port *port) |
e0495736 | 121 | { |
ecbbfd44 | 122 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
123 | struct tty_buffer *thead; |
124 | ||
64325a3b IZ |
125 | if (unlikely(buf->head == NULL)) |
126 | return; | |
127 | while ((thead = buf->head->next) != NULL) { | |
128 | tty_buffer_free(port, buf->head); | |
129 | buf->head = thead; | |
e0495736 | 130 | } |
64325a3b IZ |
131 | WARN_ON(buf->head != buf->tail); |
132 | buf->head->read = buf->head->commit; | |
e0495736 AC |
133 | } |
134 | ||
135 | /** | |
136 | * tty_buffer_flush - flush full tty buffers | |
137 | * @tty: tty to flush | |
138 | * | |
139 | * flush all the buffers containing receive data. If the buffer is | |
140 | * being processed by flush_to_ldisc then we defer the processing | |
141 | * to that function | |
142 | * | |
143 | * Locking: none | |
144 | */ | |
145 | ||
146 | void tty_buffer_flush(struct tty_struct *tty) | |
147 | { | |
2fc20661 | 148 | struct tty_port *port = tty->port; |
ecbbfd44 | 149 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 150 | unsigned long flags; |
5cff39c6 JS |
151 | |
152 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
153 | |
154 | /* If the data is being pushed to the tty layer then we can't | |
155 | process it here. Instead set a flag and the flush_to_ldisc | |
156 | path will process the flush request before it exits */ | |
2fc20661 JS |
157 | if (test_bit(TTYP_FLUSHING, &port->iflags)) { |
158 | set_bit(TTYP_FLUSHPENDING, &port->iflags); | |
5cff39c6 | 159 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 | 160 | wait_event(tty->read_wait, |
2fc20661 | 161 | test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); |
e0495736 AC |
162 | return; |
163 | } else | |
ecbbfd44 | 164 | __tty_buffer_flush(port); |
5cff39c6 | 165 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
166 | } |
167 | ||
168 | /** | |
169 | * tty_buffer_find - find a free tty buffer | |
170 | * @tty: tty owning the buffer | |
171 | * @size: characters wanted | |
172 | * | |
173 | * Locate an existing suitable tty buffer or if we are lacking one then | |
174 | * allocate a new one. We round our buffers off in 256 character chunks | |
175 | * to get better allocation behaviour. | |
176 | * | |
177 | * Locking: Caller must hold tty->buf.lock | |
178 | */ | |
179 | ||
ecbbfd44 | 180 | static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size) |
e0495736 | 181 | { |
ecbbfd44 | 182 | struct tty_buffer **tbh = &port->buf.free; |
1cef50e3 PH |
183 | if (size <= MIN_TTYB_SIZE) { |
184 | if (*tbh) { | |
185 | struct tty_buffer *t = *tbh; | |
186 | ||
e0495736 AC |
187 | *tbh = t->next; |
188 | t->next = NULL; | |
189 | t->used = 0; | |
190 | t->commit = 0; | |
191 | t->read = 0; | |
ecbbfd44 | 192 | port->buf.memory_used += t->size; |
e0495736 AC |
193 | return t; |
194 | } | |
e0495736 AC |
195 | } |
196 | /* Round the buffer size out */ | |
1cef50e3 | 197 | size = __ALIGN_MASK(size, TTYB_ALIGN_MASK); |
ecbbfd44 | 198 | return tty_buffer_alloc(port, size); |
e0495736 AC |
199 | /* Should possibly check if this fails for the largest buffer we |
200 | have queued and recycle that ? */ | |
201 | } | |
e0495736 | 202 | /** |
64325a3b | 203 | * tty_buffer_request_room - grow tty buffer if needed |
e0495736 AC |
204 | * @tty: tty structure |
205 | * @size: size desired | |
206 | * | |
207 | * Make at least size bytes of linear space available for the tty | |
208 | * buffer. If we fail return the size we managed to find. | |
64325a3b IZ |
209 | * |
210 | * Locking: Takes port->buf.lock | |
e0495736 | 211 | */ |
64325a3b | 212 | int tty_buffer_request_room(struct tty_port *port, size_t size) |
e0495736 | 213 | { |
ecbbfd44 | 214 | struct tty_bufhead *buf = &port->buf; |
e0495736 AC |
215 | struct tty_buffer *b, *n; |
216 | int left; | |
64325a3b IZ |
217 | unsigned long flags; |
218 | spin_lock_irqsave(&buf->lock, flags); | |
e0495736 AC |
219 | /* OPTIMISATION: We could keep a per tty "zero" sized buffer to |
220 | remove this conditional if its worth it. This would be invisible | |
221 | to the callers */ | |
5cff39c6 JS |
222 | b = buf->tail; |
223 | if (b != NULL) | |
e0495736 AC |
224 | left = b->size - b->used; |
225 | else | |
226 | left = 0; | |
227 | ||
228 | if (left < size) { | |
229 | /* This is the slow path - looking for new buffers to use */ | |
ecbbfd44 | 230 | if ((n = tty_buffer_find(port, size)) != NULL) { |
e0495736 AC |
231 | if (b != NULL) { |
232 | b->next = n; | |
233 | b->commit = b->used; | |
234 | } else | |
5cff39c6 JS |
235 | buf->head = n; |
236 | buf->tail = n; | |
e0495736 AC |
237 | } else |
238 | size = left; | |
239 | } | |
64325a3b | 240 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
241 | return size; |
242 | } | |
243 | EXPORT_SYMBOL_GPL(tty_buffer_request_room); | |
244 | ||
245 | /** | |
2832fc11 | 246 | * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer |
2f693357 | 247 | * @port: tty port |
e0495736 | 248 | * @chars: characters |
2832fc11 | 249 | * @flag: flag value for each character |
e0495736 AC |
250 | * @size: size |
251 | * | |
252 | * Queue a series of bytes to the tty buffering. All the characters | |
ccc5ca8d | 253 | * passed are marked with the supplied flag. Returns the number added. |
e0495736 | 254 | * |
ecbbfd44 | 255 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
256 | */ |
257 | ||
2f693357 | 258 | int tty_insert_flip_string_fixed_flag(struct tty_port *port, |
2832fc11 | 259 | const unsigned char *chars, char flag, size_t size) |
e0495736 AC |
260 | { |
261 | int copied = 0; | |
262 | do { | |
d4bee0a6 | 263 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
264 | int space = tty_buffer_request_room(port, goal); |
265 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 266 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 267 | if (unlikely(space == 0)) { |
e0495736 | 268 | break; |
c56a00a1 | 269 | } |
1fc359fc PH |
270 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
271 | memset(flag_buf_ptr(tb, tb->used), flag, space); | |
e0495736 AC |
272 | tb->used += space; |
273 | copied += space; | |
274 | chars += space; | |
275 | /* There is a small chance that we need to split the data over | |
276 | several buffers. If this is the case we must loop */ | |
277 | } while (unlikely(size > copied)); | |
278 | return copied; | |
279 | } | |
2832fc11 | 280 | EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); |
e0495736 AC |
281 | |
282 | /** | |
283 | * tty_insert_flip_string_flags - Add characters to the tty buffer | |
2f693357 | 284 | * @port: tty port |
e0495736 AC |
285 | * @chars: characters |
286 | * @flags: flag bytes | |
287 | * @size: size | |
288 | * | |
289 | * Queue a series of bytes to the tty buffering. For each character | |
290 | * the flags array indicates the status of the character. Returns the | |
291 | * number added. | |
292 | * | |
ecbbfd44 | 293 | * Locking: Called functions may take port->buf.lock |
e0495736 AC |
294 | */ |
295 | ||
2f693357 | 296 | int tty_insert_flip_string_flags(struct tty_port *port, |
e0495736 AC |
297 | const unsigned char *chars, const char *flags, size_t size) |
298 | { | |
299 | int copied = 0; | |
300 | do { | |
d4bee0a6 | 301 | int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); |
64325a3b IZ |
302 | int space = tty_buffer_request_room(port, goal); |
303 | struct tty_buffer *tb = port->buf.tail; | |
e0495736 | 304 | /* If there is no space then tb may be NULL */ |
c56a00a1 | 305 | if (unlikely(space == 0)) { |
e0495736 | 306 | break; |
c56a00a1 | 307 | } |
1fc359fc PH |
308 | memcpy(char_buf_ptr(tb, tb->used), chars, space); |
309 | memcpy(flag_buf_ptr(tb, tb->used), flags, space); | |
e0495736 AC |
310 | tb->used += space; |
311 | copied += space; | |
312 | chars += space; | |
313 | flags += space; | |
314 | /* There is a small chance that we need to split the data over | |
315 | several buffers. If this is the case we must loop */ | |
316 | } while (unlikely(size > copied)); | |
317 | return copied; | |
318 | } | |
319 | EXPORT_SYMBOL(tty_insert_flip_string_flags); | |
320 | ||
321 | /** | |
322 | * tty_schedule_flip - push characters to ldisc | |
6732c8bb | 323 | * @port: tty port to push from |
e0495736 AC |
324 | * |
325 | * Takes any pending buffers and transfers their ownership to the | |
326 | * ldisc side of the queue. It then schedules those characters for | |
327 | * processing by the line discipline. | |
cee4ad1e IS |
328 | * Note that this function can only be used when the low_latency flag |
329 | * is unset. Otherwise the workqueue won't be flushed. | |
e0495736 | 330 | * |
ecbbfd44 | 331 | * Locking: Takes port->buf.lock |
e0495736 AC |
332 | */ |
333 | ||
6732c8bb | 334 | void tty_schedule_flip(struct tty_port *port) |
e0495736 | 335 | { |
6732c8bb | 336 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 337 | unsigned long flags; |
6732c8bb | 338 | WARN_ON(port->low_latency); |
5cff39c6 JS |
339 | |
340 | spin_lock_irqsave(&buf->lock, flags); | |
341 | if (buf->tail != NULL) | |
342 | buf->tail->commit = buf->tail->used; | |
343 | spin_unlock_irqrestore(&buf->lock, flags); | |
344 | schedule_work(&buf->work); | |
e0495736 AC |
345 | } |
346 | EXPORT_SYMBOL(tty_schedule_flip); | |
347 | ||
348 | /** | |
349 | * tty_prepare_flip_string - make room for characters | |
2f693357 | 350 | * @port: tty port |
e0495736 AC |
351 | * @chars: return pointer for character write area |
352 | * @size: desired size | |
353 | * | |
354 | * Prepare a block of space in the buffer for data. Returns the length | |
355 | * available and buffer pointer to the space which is now allocated and | |
356 | * accounted for as ready for normal characters. This is used for drivers | |
357 | * that need their own block copy routines into the buffer. There is no | |
358 | * guarantee the buffer is a DMA target! | |
359 | * | |
ecbbfd44 | 360 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
361 | */ |
362 | ||
2f693357 | 363 | int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, |
ecbbfd44 | 364 | size_t size) |
e0495736 | 365 | { |
64325a3b | 366 | int space = tty_buffer_request_room(port, size); |
e0495736 | 367 | if (likely(space)) { |
64325a3b | 368 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
369 | *chars = char_buf_ptr(tb, tb->used); |
370 | memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space); | |
e0495736 AC |
371 | tb->used += space; |
372 | } | |
373 | return space; | |
374 | } | |
375 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string); | |
376 | ||
377 | /** | |
378 | * tty_prepare_flip_string_flags - make room for characters | |
2f693357 | 379 | * @port: tty port |
e0495736 AC |
380 | * @chars: return pointer for character write area |
381 | * @flags: return pointer for status flag write area | |
382 | * @size: desired size | |
383 | * | |
384 | * Prepare a block of space in the buffer for data. Returns the length | |
385 | * available and buffer pointer to the space which is now allocated and | |
386 | * accounted for as ready for characters. This is used for drivers | |
387 | * that need their own block copy routines into the buffer. There is no | |
388 | * guarantee the buffer is a DMA target! | |
389 | * | |
ecbbfd44 | 390 | * Locking: May call functions taking port->buf.lock |
e0495736 AC |
391 | */ |
392 | ||
2f693357 | 393 | int tty_prepare_flip_string_flags(struct tty_port *port, |
e0495736 AC |
394 | unsigned char **chars, char **flags, size_t size) |
395 | { | |
64325a3b | 396 | int space = tty_buffer_request_room(port, size); |
e0495736 | 397 | if (likely(space)) { |
64325a3b | 398 | struct tty_buffer *tb = port->buf.tail; |
1fc359fc PH |
399 | *chars = char_buf_ptr(tb, tb->used); |
400 | *flags = flag_buf_ptr(tb, tb->used); | |
e0495736 AC |
401 | tb->used += space; |
402 | } | |
403 | return space; | |
404 | } | |
405 | EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); | |
406 | ||
407 | ||
da261e7f PH |
408 | static int |
409 | receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) | |
410 | { | |
411 | struct tty_ldisc *disc = tty->ldisc; | |
1fc359fc PH |
412 | unsigned char *p = char_buf_ptr(head, head->read); |
413 | char *f = flag_buf_ptr(head, head->read); | |
da261e7f | 414 | |
24a89d1c PH |
415 | if (disc->ops->receive_buf2) |
416 | count = disc->ops->receive_buf2(tty, p, f, count); | |
417 | else { | |
418 | count = min_t(int, count, tty->receive_room); | |
419 | if (count) | |
420 | disc->ops->receive_buf(tty, p, f, count); | |
421 | } | |
da261e7f PH |
422 | head->read += count; |
423 | return count; | |
424 | } | |
e0495736 AC |
425 | |
426 | /** | |
427 | * flush_to_ldisc | |
428 | * @work: tty structure passed from work queue. | |
429 | * | |
430 | * This routine is called out of the software interrupt to flush data | |
431 | * from the buffer chain to the line discipline. | |
432 | * | |
433 | * Locking: holds tty->buf.lock to guard buffer list. Drops the lock | |
434 | * while invoking the line discipline receive_buf method. The | |
435 | * receive_buf method is single threaded for each tty instance. | |
436 | */ | |
437 | ||
438 | static void flush_to_ldisc(struct work_struct *work) | |
439 | { | |
ecbbfd44 JS |
440 | struct tty_port *port = container_of(work, struct tty_port, buf.work); |
441 | struct tty_bufhead *buf = &port->buf; | |
442 | struct tty_struct *tty; | |
e0495736 AC |
443 | unsigned long flags; |
444 | struct tty_ldisc *disc; | |
e0495736 | 445 | |
ecbbfd44 | 446 | tty = port->itty; |
34dcfb84 | 447 | if (tty == NULL) |
ecbbfd44 JS |
448 | return; |
449 | ||
e0495736 | 450 | disc = tty_ldisc_ref(tty); |
36697529 | 451 | if (disc == NULL) |
e0495736 AC |
452 | return; |
453 | ||
5cff39c6 | 454 | spin_lock_irqsave(&buf->lock, flags); |
45242006 | 455 | |
2fc20661 | 456 | if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { |
81de916f | 457 | struct tty_buffer *head; |
5cff39c6 | 458 | while ((head = buf->head) != NULL) { |
45242006 | 459 | int count; |
45242006 LT |
460 | |
461 | count = head->commit - head->read; | |
e0495736 AC |
462 | if (!count) { |
463 | if (head->next == NULL) | |
464 | break; | |
5cff39c6 | 465 | buf->head = head->next; |
ecbbfd44 | 466 | tty_buffer_free(port, head); |
e0495736 AC |
467 | continue; |
468 | } | |
5cff39c6 | 469 | spin_unlock_irqrestore(&buf->lock, flags); |
da261e7f PH |
470 | |
471 | count = receive_buf(tty, head, count); | |
472 | ||
5cff39c6 | 473 | spin_lock_irqsave(&buf->lock, flags); |
39f610e4 PH |
474 | /* Ldisc or user is trying to flush the buffers. |
475 | We may have a deferred request to flush the | |
476 | input buffer, if so pull the chain under the lock | |
477 | and empty the queue */ | |
478 | if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) { | |
479 | __tty_buffer_flush(port); | |
480 | clear_bit(TTYP_FLUSHPENDING, &port->iflags); | |
481 | wake_up(&tty->read_wait); | |
482 | break; | |
da261e7f PH |
483 | } else if (!count) |
484 | break; | |
e0495736 | 485 | } |
2fc20661 | 486 | clear_bit(TTYP_FLUSHING, &port->iflags); |
e0495736 | 487 | } |
45242006 | 488 | |
5cff39c6 | 489 | spin_unlock_irqrestore(&buf->lock, flags); |
e0495736 AC |
490 | |
491 | tty_ldisc_deref(disc); | |
492 | } | |
493 | ||
e043e42b OH |
494 | /** |
495 | * tty_flush_to_ldisc | |
496 | * @tty: tty to push | |
497 | * | |
498 | * Push the terminal flip buffers to the line discipline. | |
499 | * | |
500 | * Must not be called from IRQ context. | |
501 | */ | |
502 | void tty_flush_to_ldisc(struct tty_struct *tty) | |
503 | { | |
d6c53c0e | 504 | if (!tty->port->low_latency) |
ecbbfd44 | 505 | flush_work(&tty->port->buf.work); |
e043e42b OH |
506 | } |
507 | ||
e0495736 AC |
508 | /** |
509 | * tty_flip_buffer_push - terminal | |
2e124b4a | 510 | * @port: tty port to push |
e0495736 AC |
511 | * |
512 | * Queue a push of the terminal flip buffers to the line discipline. This | |
d6c53c0e JS |
513 | * function must not be called from IRQ context if port->low_latency is |
514 | * set. | |
e0495736 AC |
515 | * |
516 | * In the event of the queue being busy for flipping the work will be | |
517 | * held off and retried later. | |
518 | * | |
519 | * Locking: tty buffer lock. Driver locks in low latency mode. | |
520 | */ | |
521 | ||
2e124b4a | 522 | void tty_flip_buffer_push(struct tty_port *port) |
e0495736 | 523 | { |
2e124b4a | 524 | struct tty_bufhead *buf = &port->buf; |
e0495736 | 525 | unsigned long flags; |
5cff39c6 JS |
526 | |
527 | spin_lock_irqsave(&buf->lock, flags); | |
528 | if (buf->tail != NULL) | |
529 | buf->tail->commit = buf->tail->used; | |
530 | spin_unlock_irqrestore(&buf->lock, flags); | |
e0495736 | 531 | |
2e124b4a | 532 | if (port->low_latency) |
5cff39c6 | 533 | flush_to_ldisc(&buf->work); |
e0495736 | 534 | else |
5cff39c6 | 535 | schedule_work(&buf->work); |
e0495736 AC |
536 | } |
537 | EXPORT_SYMBOL(tty_flip_buffer_push); | |
538 | ||
539 | /** | |
540 | * tty_buffer_init - prepare a tty buffer structure | |
541 | * @tty: tty to initialise | |
542 | * | |
543 | * Set up the initial state of the buffer management for a tty device. | |
544 | * Must be called before the other tty buffer functions are used. | |
545 | * | |
546 | * Locking: none | |
547 | */ | |
548 | ||
ecbbfd44 | 549 | void tty_buffer_init(struct tty_port *port) |
e0495736 | 550 | { |
ecbbfd44 | 551 | struct tty_bufhead *buf = &port->buf; |
5cff39c6 JS |
552 | |
553 | spin_lock_init(&buf->lock); | |
554 | buf->head = NULL; | |
555 | buf->tail = NULL; | |
556 | buf->free = NULL; | |
557 | buf->memory_used = 0; | |
558 | INIT_WORK(&buf->work, flush_to_ldisc); | |
e0495736 AC |
559 | } |
560 |