1
2
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/wait.h>
15#include <linux/bitops.h>
16#include <linux/delay.h>
17#include <linux/module.h>
18#include <linux/ratelimit.h>
19
20
21#define MIN_TTYB_SIZE 256
22#define TTYB_ALIGN_MASK 255
23
24
25
26
27
28#define TTYB_DEFAULT_MEM_LIMIT 65536
29
30
31
32
33
34
35
36
37
38#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
39
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
212void tty_buffer_flush(struct tty_struct *tty)
213{
214 struct tty_port *port = tty->port;
215 struct tty_bufhead *buf = &port->buf;
216 struct tty_buffer *next;
217
218 atomic_inc(&buf->priority);
219
220 mutex_lock(&buf->lock);
221 while ((next = buf->head->next) != NULL) {
222 tty_buffer_free(port, buf->head);
223 buf->head = next;
224 }
225 buf->head->read = buf->head->commit;
226 atomic_dec(&buf->priority);
227 mutex_unlock(&buf->lock);
228}
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243static int __tty_buffer_request_room(struct tty_port *port, size_t size,
244 int flags)
245{
246 struct tty_bufhead *buf = &port->buf;
247 struct tty_buffer *b, *n;
248 int left, change;
249
250 b = buf->tail;
251 if (b->flags & TTYB_NORMAL)
252 left = 2 * b->size - b->used;
253 else
254 left = b->size - b->used;
255
256 change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL);
257 if (change || left < size) {
258
259 if ((n = tty_buffer_alloc(port, size)) != NULL) {
260 n->flags = flags;
261 buf->tail = n;
262 b->commit = b->used;
263
264
265
266
267 smp_wmb();
268 b->next = n;
269 } else if (change)
270 size = 0;
271 else
272 size = left;
273 }
274 return size;
275}
276
277int tty_buffer_request_room(struct tty_port *port, size_t size)
278{
279 return __tty_buffer_request_room(port, size, 0);
280}
281EXPORT_SYMBOL_GPL(tty_buffer_request_room);
282
283
284
285
286
287
288
289
290
291
292
293
294int tty_insert_flip_string_fixed_flag(struct tty_port *port,
295 const unsigned char *chars, char flag, size_t size)
296{
297 int copied = 0;
298 do {
299 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
300 int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;
301 int space = __tty_buffer_request_room(port, goal, flags);
302 struct tty_buffer *tb = port->buf.tail;
303 if (unlikely(space == 0))
304 break;
305 memcpy(char_buf_ptr(tb, tb->used), chars, space);
306 if (~tb->flags & TTYB_NORMAL)
307 memset(flag_buf_ptr(tb, tb->used), flag, space);
308 tb->used += space;
309 copied += space;
310 chars += space;
311
312
313 } while (unlikely(size > copied));
314 return copied;
315}
316EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
317
318
319
320
321
322
323
324
325
326
327
328
329
330int tty_insert_flip_string_flags(struct tty_port *port,
331 const unsigned char *chars, const char *flags, size_t size)
332{
333 int copied = 0;
334 do {
335 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
336 int space = tty_buffer_request_room(port, goal);
337 struct tty_buffer *tb = port->buf.tail;
338 if (unlikely(space == 0))
339 break;
340 memcpy(char_buf_ptr(tb, tb->used), chars, space);
341 memcpy(flag_buf_ptr(tb, tb->used), flags, space);
342 tb->used += space;
343 copied += space;
344 chars += space;
345 flags += space;
346
347
348 } while (unlikely(size > copied));
349 return copied;
350}
351EXPORT_SYMBOL(tty_insert_flip_string_flags);
352
353
354
355
356
357
358
359
360
361
362void tty_schedule_flip(struct tty_port *port)
363{
364 struct tty_bufhead *buf = &port->buf;
365
366 buf->tail->commit = buf->tail->used;
367 schedule_work(&buf->work);
368}
369EXPORT_SYMBOL(tty_schedule_flip);
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars,
385 size_t size)
386{
387 int space = __tty_buffer_request_room(port, size, TTYB_NORMAL);
388 if (likely(space)) {
389 struct tty_buffer *tb = port->buf.tail;
390 *chars = char_buf_ptr(tb, tb->used);
391 if (~tb->flags & TTYB_NORMAL)
392 memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
393 tb->used += space;
394 }
395 return space;
396}
397EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
398
399
400static int
401receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
402{
403 struct tty_ldisc *disc = tty->ldisc;
404 unsigned char *p = char_buf_ptr(head, head->read);
405 char *f = NULL;
406
407 if (~head->flags & TTYB_NORMAL)
408 f = flag_buf_ptr(head, head->read);
409
410 if (disc->ops->receive_buf2)
411 count = disc->ops->receive_buf2(tty, p, f, count);
412 else {
413 count = min_t(int, count, tty->receive_room);
414 if (count)
415 disc->ops->receive_buf(tty, p, f, count);
416 }
417 head->read += count;
418 return count;
419}
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434static void flush_to_ldisc(struct work_struct *work)
435{
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;
439 struct tty_ldisc *disc;
440
441 tty = port->itty;
442 if (tty == NULL)
443 return;
444
445 disc = tty_ldisc_ref(tty);
446 if (disc == NULL)
447 return;
448
449 mutex_lock(&buf->lock);
450
451 while (1) {
452 struct tty_buffer *head = buf->head;
453 struct tty_buffer *next;
454 int count;
455
456
457 if (atomic_read(&buf->priority))
458 break;
459
460 next = head->next;
461
462
463
464
465 smp_rmb();
466 count = head->commit - head->read;
467 if (!count) {
468 if (next == NULL)
469 break;
470 buf->head = next;
471 tty_buffer_free(port, head);
472 continue;
473 }
474
475 count = receive_buf(tty, head, count);
476 if (!count)
477 break;
478 }
479
480 mutex_unlock(&buf->lock);
481
482 tty_ldisc_deref(disc);
483}
484
485
486
487
488
489
490
491
492
493void tty_flush_to_ldisc(struct tty_struct *tty)
494{
495 flush_work(&tty->port->buf.work);
496}
497
498
499
500
501
502
503
504
505
506
507
508
509void tty_flip_buffer_push(struct tty_port *port)
510{
511 tty_schedule_flip(port);
512}
513EXPORT_SYMBOL(tty_flip_buffer_push);
514
515
516
517
518
519
520
521
522
523void tty_buffer_init(struct tty_port *port)
524{
525 struct tty_bufhead *buf = &port->buf;
526
527 mutex_init(&buf->lock);
528 tty_buffer_reset(&buf->sentinel, 0);
529 buf->head = &buf->sentinel;
530 buf->tail = &buf->sentinel;
531 init_llist_head(&buf->free);
532 atomic_set(&buf->mem_used, 0);
533 atomic_set(&buf->priority, 0);
534 INIT_WORK(&buf->work, flush_to_ldisc);
535 buf->mem_limit = TTYB_DEFAULT_MEM_LIMIT;
536}
537
538
539
540
541
542
543
544
545
546int tty_buffer_set_limit(struct tty_port *port, int limit)
547{
548 if (limit < MIN_TTYB_SIZE)
549 return -EINVAL;
550 port->buf.mem_limit = limit;
551 return 0;
552}
553EXPORT_SYMBOL_GPL(tty_buffer_set_limit);
554