1
2
3
4
5
6#include <linux/types.h>
7#include <linux/errno.h>
8#include <linux/tty.h>
9#include <linux/tty_driver.h>
10#include <linux/tty_flip.h>
11#include <linux/timer.h>
12#include <linux/string.h>
13#include <linux/slab.h>
14#include <linux/sched.h>
15#include <linux/wait.h>
16#include <linux/bitops.h>
17#include <linux/delay.h>
18#include <linux/module.h>
19#include <linux/ratelimit.h>
20
21
22#define MIN_TTYB_SIZE 256
23#define TTYB_ALIGN_MASK 255
24
25
26
27
28
29#define TTYB_DEFAULT_MEM_LIMIT 65536
30
31
32
33
34
35
36
37
38
39#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56void tty_buffer_lock_exclusive(struct tty_port *port)
57{
58 struct tty_bufhead *buf = &port->buf;
59
60 atomic_inc(&buf->priority);
61 mutex_lock(&buf->lock);
62}
63EXPORT_SYMBOL_GPL(tty_buffer_lock_exclusive);
64
65void tty_buffer_unlock_exclusive(struct tty_port *port)
66{
67 struct tty_bufhead *buf = &port->buf;
68 int restart;
69
70 restart = buf->head->commit != buf->head->read;
71
72 atomic_dec(&buf->priority);
73 mutex_unlock(&buf->lock);
74 if (restart)
75 queue_work(system_unbound_wq, &buf->work);
76}
77EXPORT_SYMBOL_GPL(tty_buffer_unlock_exclusive);
78
79
80
81
82
83
84
85
86
87
88
89
90
91int tty_buffer_space_avail(struct tty_port *port)
92{
93 int space = port->buf.mem_limit - atomic_read(&port->buf.mem_used);
94 return max(space, 0);
95}
96EXPORT_SYMBOL_GPL(tty_buffer_space_avail);
97
98static void tty_buffer_reset(struct tty_buffer *p, size_t size)
99{
100 p->used = 0;
101 p->size = size;
102 p->next = NULL;
103 p->commit = 0;
104 p->read = 0;
105 p->flags = 0;
106}
107
108
109
110
111
112
113
114
115
116void tty_buffer_free_all(struct tty_port *port)
117{
118 struct tty_bufhead *buf = &port->buf;
119 struct tty_buffer *p, *next;
120 struct llist_node *llist;
121
122 while ((p = buf->head) != NULL) {
123 buf->head = p->next;
124 if (p->size > 0)
125 kfree(p);
126 }
127 llist = llist_del_all(&buf->free);
128 llist_for_each_entry_safe(p, next, llist, free)
129 kfree(p);
130
131 tty_buffer_reset(&buf->sentinel, 0);
132 buf->head = &buf->sentinel;
133 buf->tail = &buf->sentinel;
134
135 atomic_set(&buf->mem_used, 0);
136}
137
138
139
140
141
142
143
144
145
146
147
148
149
150static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
151{
152 struct llist_node *free;
153 struct tty_buffer *p;
154
155
156 size = __ALIGN_MASK(size, TTYB_ALIGN_MASK);
157
158 if (size <= MIN_TTYB_SIZE) {
159 free = llist_del_first(&port->buf.free);
160 if (free) {
161 p = llist_entry(free, struct tty_buffer, free);
162 goto found;
163 }
164 }
165
166
167
168 if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit)
169 return NULL;
170 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
171 if (p == NULL)
172 return NULL;
173
174found:
175 tty_buffer_reset(p, size);
176 atomic_add(size, &port->buf.mem_used);
177 return p;
178}
179
180
181
182
183
184
185
186
187
188
189static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b)
190{
191 struct tty_bufhead *buf = &port->buf;
192
193
194 WARN_ON(atomic_sub_return(b->size, &buf->mem_used) < 0);
195
196 if (b->size > MIN_TTYB_SIZE)
197 kfree(b);
198 else if (b->size > 0)
199 llist_add(&b->free, &buf->free);
200}
201
202
203
204
205
206
207
208
209
210
211
212
213
214void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
215{
216 struct tty_port *port = tty->port;
217 struct tty_bufhead *buf = &port->buf;
218 struct tty_buffer *next;
219
220 atomic_inc(&buf->priority);
221
222 mutex_lock(&buf->lock);
223
224
225
226 while ((next = smp_load_acquire(&buf->head->next)) != NULL) {
227 tty_buffer_free(port, buf->head);
228 buf->head = next;
229 }
230 buf->head->read = buf->head->commit;
231
232 if (ld && ld->ops->flush_buffer)
233 ld->ops->flush_buffer(tty);
234
235 atomic_dec(&buf->priority);
236 mutex_unlock(&buf->lock);
237}
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252static int __tty_buffer_request_room(struct tty_port *port, size_t size,
253 int flags)
254{
255 struct tty_bufhead *buf = &port->buf;
256 struct tty_buffer *b, *n;
257 int left, change;
258
259 b = buf->tail;
260 if (b->flags & TTYB_NORMAL)
261 left = 2 * b->size - b->used;
262 else
263 left = b->size - b->used;
264
265 change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL);
266 if (change || left < size) {
267
268 n = tty_buffer_alloc(port, size);
269 if (n != NULL) {
270 n->flags = flags;
271 buf->tail = n;
272
273
274
275 smp_store_release(&b->commit, b->used);
276
277
278
279
280 smp_store_release(&b->next, n);
281 } else if (change)
282 size = 0;
283 else
284 size = left;
285 }
286 return size;
287}
288
289int tty_buffer_request_room(struct tty_port *port, size_t size)
290{
291 return __tty_buffer_request_room(port, size, 0);
292}
293EXPORT_SYMBOL_GPL(tty_buffer_request_room);
294
295
296
297
298
299
300
301
302
303
304
305
306int tty_insert_flip_string_fixed_flag(struct tty_port *port,
307 const unsigned char *chars, char flag, size_t size)
308{
309 int copied = 0;
310 do {
311 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
312 int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;
313 int space = __tty_buffer_request_room(port, goal, flags);
314 struct tty_buffer *tb = port->buf.tail;
315 if (unlikely(space == 0))
316 break;
317 memcpy(char_buf_ptr(tb, tb->used), chars, space);
318 if (~tb->flags & TTYB_NORMAL)
319 memset(flag_buf_ptr(tb, tb->used), flag, space);
320 tb->used += space;
321 copied += space;
322 chars += space;
323
324
325 } while (unlikely(size > copied));
326 return copied;
327}
328EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
329
330
331
332
333
334
335
336
337
338
339
340
341
342int tty_insert_flip_string_flags(struct tty_port *port,
343 const unsigned char *chars, const char *flags, size_t size)
344{
345 int copied = 0;
346 do {
347 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
348 int space = tty_buffer_request_room(port, goal);
349 struct tty_buffer *tb = port->buf.tail;
350 if (unlikely(space == 0))
351 break;
352 memcpy(char_buf_ptr(tb, tb->used), chars, space);
353 memcpy(flag_buf_ptr(tb, tb->used), flags, space);
354 tb->used += space;
355 copied += space;
356 chars += space;
357 flags += space;
358
359
360 } while (unlikely(size > copied));
361 return copied;
362}
363EXPORT_SYMBOL(tty_insert_flip_string_flags);
364
365
366
367
368
369
370
371
372
373
374int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag)
375{
376 struct tty_buffer *tb;
377 int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;
378
379 if (!__tty_buffer_request_room(port, 1, flags))
380 return 0;
381
382 tb = port->buf.tail;
383 if (~tb->flags & TTYB_NORMAL)
384 *flag_buf_ptr(tb, tb->used) = flag;
385 *char_buf_ptr(tb, tb->used++) = ch;
386
387 return 1;
388}
389EXPORT_SYMBOL(__tty_insert_flip_char);
390
391
392
393
394
395
396
397
398
399
400void tty_schedule_flip(struct tty_port *port)
401{
402 struct tty_bufhead *buf = &port->buf;
403
404
405
406
407 smp_store_release(&buf->tail->commit, buf->tail->used);
408 queue_work(system_unbound_wq, &buf->work);
409}
410EXPORT_SYMBOL(tty_schedule_flip);
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars,
426 size_t size)
427{
428 int space = __tty_buffer_request_room(port, size, TTYB_NORMAL);
429 if (likely(space)) {
430 struct tty_buffer *tb = port->buf.tail;
431 *chars = char_buf_ptr(tb, tb->used);
432 if (~tb->flags & TTYB_NORMAL)
433 memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
434 tb->used += space;
435 }
436 return space;
437}
438EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
439
440
441
442
443
444
445
446
447
448
449
450
451
452int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
453 char *f, int count)
454{
455 if (ld->ops->receive_buf2)
456 count = ld->ops->receive_buf2(ld->tty, p, f, count);
457 else {
458 count = min_t(int, count, ld->tty->receive_room);
459 if (count && ld->ops->receive_buf)
460 ld->ops->receive_buf(ld->tty, p, f, count);
461 }
462 return count;
463}
464EXPORT_SYMBOL_GPL(tty_ldisc_receive_buf);
465
466static int
467receive_buf(struct tty_port *port, struct tty_buffer *head, int count)
468{
469 unsigned char *p = char_buf_ptr(head, head->read);
470 char *f = NULL;
471 int n;
472
473 if (~head->flags & TTYB_NORMAL)
474 f = flag_buf_ptr(head, head->read);
475
476 n = port->client_ops->receive_buf(port, p, f, count);
477 if (n > 0)
478 memset(p, 0, n);
479 return n;
480}
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495static void flush_to_ldisc(struct work_struct *work)
496{
497 struct tty_port *port = container_of(work, struct tty_port, buf.work);
498 struct tty_bufhead *buf = &port->buf;
499
500 mutex_lock(&buf->lock);
501
502 while (1) {
503 struct tty_buffer *head = buf->head;
504 struct tty_buffer *next;
505 int count;
506
507
508 if (atomic_read(&buf->priority))
509 break;
510
511
512
513
514
515 next = smp_load_acquire(&head->next);
516
517
518
519 count = smp_load_acquire(&head->commit) - head->read;
520 if (!count) {
521 if (next == NULL)
522 break;
523 buf->head = next;
524 tty_buffer_free(port, head);
525 continue;
526 }
527
528 count = receive_buf(port, head, count);
529 if (!count)
530 break;
531 head->read += count;
532 }
533
534 mutex_unlock(&buf->lock);
535
536}
537
538
539
540
541
542
543
544
545
546
547
548
549void tty_flip_buffer_push(struct tty_port *port)
550{
551 tty_schedule_flip(port);
552}
553EXPORT_SYMBOL(tty_flip_buffer_push);
554
555
556
557
558
559
560
561
562
563void tty_buffer_init(struct tty_port *port)
564{
565 struct tty_bufhead *buf = &port->buf;
566
567 mutex_init(&buf->lock);
568 tty_buffer_reset(&buf->sentinel, 0);
569 buf->head = &buf->sentinel;
570 buf->tail = &buf->sentinel;
571 init_llist_head(&buf->free);
572 atomic_set(&buf->mem_used, 0);
573 atomic_set(&buf->priority, 0);
574 INIT_WORK(&buf->work, flush_to_ldisc);
575 buf->mem_limit = TTYB_DEFAULT_MEM_LIMIT;
576}
577
578
579
580
581
582
583
584
585
586int tty_buffer_set_limit(struct tty_port *port, int limit)
587{
588 if (limit < MIN_TTYB_SIZE)
589 return -EINVAL;
590 port->buf.mem_limit = limit;
591 return 0;
592}
593EXPORT_SYMBOL_GPL(tty_buffer_set_limit);
594
595
596void tty_buffer_set_lock_subclass(struct tty_port *port)
597{
598 lockdep_set_subclass(&port->buf.lock, TTY_LOCK_SLAVE);
599}
600
601bool tty_buffer_restart_work(struct tty_port *port)
602{
603 return queue_work(system_unbound_wq, &port->buf.work);
604}
605
606bool tty_buffer_cancel_work(struct tty_port *port)
607{
608 return cancel_work_sync(&port->buf.work);
609}
610
611void tty_buffer_flush_work(struct tty_port *port)
612{
613 flush_work(&port->buf.work);
614}
615