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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
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28#define TTYB_DEFAULT_MEM_LIMIT 65536
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37
38#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
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55void tty_buffer_lock_exclusive(struct tty_port *port)
56{
57 struct tty_bufhead *buf = &port->buf;
58
59 atomic_inc(&buf->priority);
60 mutex_lock(&buf->lock);
61}
62EXPORT_SYMBOL_GPL(tty_buffer_lock_exclusive);
63
64void tty_buffer_unlock_exclusive(struct tty_port *port)
65{
66 struct tty_bufhead *buf = &port->buf;
67 int restart;
68
69 restart = buf->head->commit != buf->head->read;
70
71 atomic_dec(&buf->priority);
72 mutex_unlock(&buf->lock);
73 if (restart)
74 queue_work(system_unbound_wq, &buf->work);
75}
76EXPORT_SYMBOL_GPL(tty_buffer_unlock_exclusive);
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90int tty_buffer_space_avail(struct tty_port *port)
91{
92 int space = port->buf.mem_limit - atomic_read(&port->buf.mem_used);
93 return max(space, 0);
94}
95EXPORT_SYMBOL_GPL(tty_buffer_space_avail);
96
97static void tty_buffer_reset(struct tty_buffer *p, size_t size)
98{
99 p->used = 0;
100 p->size = size;
101 p->next = NULL;
102 p->commit = 0;
103 p->read = 0;
104 p->flags = 0;
105}
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114
115void tty_buffer_free_all(struct tty_port *port)
116{
117 struct tty_bufhead *buf = &port->buf;
118 struct tty_buffer *p, *next;
119 struct llist_node *llist;
120
121 while ((p = buf->head) != NULL) {
122 buf->head = p->next;
123 if (p->size > 0)
124 kfree(p);
125 }
126 llist = llist_del_all(&buf->free);
127 llist_for_each_entry_safe(p, next, llist, free)
128 kfree(p);
129
130 tty_buffer_reset(&buf->sentinel, 0);
131 buf->head = &buf->sentinel;
132 buf->tail = &buf->sentinel;
133
134 atomic_set(&buf->mem_used, 0);
135}
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149static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
150{
151 struct llist_node *free;
152 struct tty_buffer *p;
153
154
155 size = __ALIGN_MASK(size, TTYB_ALIGN_MASK);
156
157 if (size <= MIN_TTYB_SIZE) {
158 free = llist_del_first(&port->buf.free);
159 if (free) {
160 p = llist_entry(free, struct tty_buffer, free);
161 goto found;
162 }
163 }
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166
167 if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit)
168 return NULL;
169 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
170 if (p == NULL)
171 return NULL;
172
173found:
174 tty_buffer_reset(p, size);
175 atomic_add(size, &port->buf.mem_used);
176 return p;
177}
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187
188static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b)
189{
190 struct tty_bufhead *buf = &port->buf;
191
192
193 WARN_ON(atomic_sub_return(b->size, &buf->mem_used) < 0);
194
195 if (b->size > MIN_TTYB_SIZE)
196 kfree(b);
197 else if (b->size > 0)
198 llist_add(&b->free, &buf->free);
199}
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213void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
214{
215 struct tty_port *port = tty->port;
216 struct tty_bufhead *buf = &port->buf;
217 struct tty_buffer *next;
218
219 atomic_inc(&buf->priority);
220
221 mutex_lock(&buf->lock);
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225 while ((next = smp_load_acquire(&buf->head->next)) != NULL) {
226 tty_buffer_free(port, buf->head);
227 buf->head = next;
228 }
229 buf->head->read = buf->head->commit;
230
231 if (ld && ld->ops->flush_buffer)
232 ld->ops->flush_buffer(tty);
233
234 atomic_dec(&buf->priority);
235 mutex_unlock(&buf->lock);
236}
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251static int __tty_buffer_request_room(struct tty_port *port, size_t size,
252 int flags)
253{
254 struct tty_bufhead *buf = &port->buf;
255 struct tty_buffer *b, *n;
256 int left, change;
257
258 b = buf->tail;
259 if (b->flags & TTYB_NORMAL)
260 left = 2 * b->size - b->used;
261 else
262 left = b->size - b->used;
263
264 change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL);
265 if (change || left < size) {
266
267 n = tty_buffer_alloc(port, size);
268 if (n != NULL) {
269 n->flags = flags;
270 buf->tail = n;
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274 smp_store_release(&b->commit, b->used);
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279 smp_store_release(&b->next, n);
280 } else if (change)
281 size = 0;
282 else
283 size = left;
284 }
285 return size;
286}
287
288int tty_buffer_request_room(struct tty_port *port, size_t size)
289{
290 return __tty_buffer_request_room(port, size, 0);
291}
292EXPORT_SYMBOL_GPL(tty_buffer_request_room);
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305int tty_insert_flip_string_fixed_flag(struct tty_port *port,
306 const unsigned char *chars, char flag, size_t size)
307{
308 int copied = 0;
309 do {
310 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
311 int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;
312 int space = __tty_buffer_request_room(port, goal, flags);
313 struct tty_buffer *tb = port->buf.tail;
314 if (unlikely(space == 0))
315 break;
316 memcpy(char_buf_ptr(tb, tb->used), chars, space);
317 if (~tb->flags & TTYB_NORMAL)
318 memset(flag_buf_ptr(tb, tb->used), flag, space);
319 tb->used += space;
320 copied += space;
321 chars += space;
322
323
324 } while (unlikely(size > copied));
325 return copied;
326}
327EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
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341int tty_insert_flip_string_flags(struct tty_port *port,
342 const unsigned char *chars, const char *flags, size_t size)
343{
344 int copied = 0;
345 do {
346 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
347 int space = tty_buffer_request_room(port, goal);
348 struct tty_buffer *tb = port->buf.tail;
349 if (unlikely(space == 0))
350 break;
351 memcpy(char_buf_ptr(tb, tb->used), chars, space);
352 memcpy(flag_buf_ptr(tb, tb->used), flags, space);
353 tb->used += space;
354 copied += space;
355 chars += space;
356 flags += space;
357
358
359 } while (unlikely(size > copied));
360 return copied;
361}
362EXPORT_SYMBOL(tty_insert_flip_string_flags);
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373void tty_schedule_flip(struct tty_port *port)
374{
375 struct tty_bufhead *buf = &port->buf;
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380 smp_store_release(&buf->tail->commit, buf->tail->used);
381 queue_work(system_unbound_wq, &buf->work);
382}
383EXPORT_SYMBOL(tty_schedule_flip);
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398int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars,
399 size_t size)
400{
401 int space = __tty_buffer_request_room(port, size, TTYB_NORMAL);
402 if (likely(space)) {
403 struct tty_buffer *tb = port->buf.tail;
404 *chars = char_buf_ptr(tb, tb->used);
405 if (~tb->flags & TTYB_NORMAL)
406 memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
407 tb->used += space;
408 }
409 return space;
410}
411EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
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425int tty_ldisc_receive_buf(struct tty_ldisc *ld, unsigned char *p,
426 char *f, int count)
427{
428 if (ld->ops->receive_buf2)
429 count = ld->ops->receive_buf2(ld->tty, p, f, count);
430 else {
431 count = min_t(int, count, ld->tty->receive_room);
432 if (count && ld->ops->receive_buf)
433 ld->ops->receive_buf(ld->tty, p, f, count);
434 }
435 return count;
436}
437EXPORT_SYMBOL_GPL(tty_ldisc_receive_buf);
438
439static int
440receive_buf(struct tty_ldisc *ld, struct tty_buffer *head, int count)
441{
442 unsigned char *p = char_buf_ptr(head, head->read);
443 char *f = NULL;
444
445 if (~head->flags & TTYB_NORMAL)
446 f = flag_buf_ptr(head, head->read);
447
448 return tty_ldisc_receive_buf(ld, p, f, count);
449}
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464static void flush_to_ldisc(struct work_struct *work)
465{
466 struct tty_port *port = container_of(work, struct tty_port, buf.work);
467 struct tty_bufhead *buf = &port->buf;
468 struct tty_struct *tty;
469 struct tty_ldisc *disc;
470
471 tty = READ_ONCE(port->itty);
472 if (tty == NULL)
473 return;
474
475 disc = tty_ldisc_ref(tty);
476 if (disc == NULL)
477 return;
478
479 mutex_lock(&buf->lock);
480
481 while (1) {
482 struct tty_buffer *head = buf->head;
483 struct tty_buffer *next;
484 int count;
485
486
487 if (atomic_read(&buf->priority))
488 break;
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494 next = smp_load_acquire(&head->next);
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498 count = smp_load_acquire(&head->commit) - head->read;
499 if (!count) {
500 if (next == NULL)
501 break;
502 buf->head = next;
503 tty_buffer_free(port, head);
504 continue;
505 }
506
507 count = receive_buf(disc, head, count);
508 if (!count)
509 break;
510 head->read += count;
511 }
512
513 mutex_unlock(&buf->lock);
514
515 tty_ldisc_deref(disc);
516}
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529void tty_flip_buffer_push(struct tty_port *port)
530{
531 tty_schedule_flip(port);
532}
533EXPORT_SYMBOL(tty_flip_buffer_push);
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543void tty_buffer_init(struct tty_port *port)
544{
545 struct tty_bufhead *buf = &port->buf;
546
547 mutex_init(&buf->lock);
548 tty_buffer_reset(&buf->sentinel, 0);
549 buf->head = &buf->sentinel;
550 buf->tail = &buf->sentinel;
551 init_llist_head(&buf->free);
552 atomic_set(&buf->mem_used, 0);
553 atomic_set(&buf->priority, 0);
554 INIT_WORK(&buf->work, flush_to_ldisc);
555 buf->mem_limit = TTYB_DEFAULT_MEM_LIMIT;
556}
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566int tty_buffer_set_limit(struct tty_port *port, int limit)
567{
568 if (limit < MIN_TTYB_SIZE)
569 return -EINVAL;
570 port->buf.mem_limit = limit;
571 return 0;
572}
573EXPORT_SYMBOL_GPL(tty_buffer_set_limit);
574
575
576void tty_buffer_set_lock_subclass(struct tty_port *port)
577{
578 lockdep_set_subclass(&port->buf.lock, TTY_LOCK_SLAVE);
579}
580
581bool tty_buffer_restart_work(struct tty_port *port)
582{
583 return queue_work(system_unbound_wq, &port->buf.work);
584}
585
586bool tty_buffer_cancel_work(struct tty_port *port)
587{
588 return cancel_work_sync(&port->buf.work);
589}
590
591void tty_buffer_flush_work(struct tty_port *port)
592{
593 flush_work(&port->buf.work);
594}
595