blob: c043136fbe5198cf0a7a8704254fc28763ecd0b9 [file] [log] [blame]
Alan Coxe0495732008-10-13 10:36:58 +01001/*
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>
George Spelvin593fb1ae42013-02-12 02:00:43 -050019#include <linux/ratelimit.h>
Alan Coxe0495732008-10-13 10:36:58 +010020
Peter Hurley1cef50e2013-06-15 09:36:02 -040021
22#define MIN_TTYB_SIZE 256
23#define TTYB_ALIGN_MASK 255
24
Peter Hurley7bfe0b72013-06-15 09:36:08 -040025/*
26 * Byte threshold to limit memory consumption for flip buffers.
27 * The actual memory limit is > 2x this amount.
28 */
29#define TTYB_MEM_LIMIT 65536
30
Peter Hurley9114fe82013-06-15 09:36:16 -040031/*
32 * We default to dicing tty buffer allocations to this many characters
33 * in order to avoid multiple page allocations. We know the size of
34 * tty_buffer itself but it must also be taken into account that the
35 * the buffer is 256 byte aligned. See tty_buffer_find for the allocation
36 * logic this must match
37 */
38
39#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
40
Peter Hurley7bfe0b72013-06-15 09:36:08 -040041
42/**
Peter Hurleya7c8d582013-06-15 09:36:15 -040043 * tty_buffer_lock_exclusive - gain exclusive access to buffer
44 * tty_buffer_unlock_exclusive - release exclusive access
45 *
46 * @port - tty_port owning the flip buffer
47 *
48 * Guarantees safe use of the line discipline's receive_buf() method by
49 * excluding the buffer work and any pending flush from using the flip
50 * buffer. Data can continue to be added concurrently to the flip buffer
51 * from the driver side.
52 *
53 * On release, the buffer work is restarted if there is data in the
54 * flip buffer
55 */
56
57void tty_buffer_lock_exclusive(struct tty_port *port)
58{
59 struct tty_bufhead *buf = &port->buf;
60
61 atomic_inc(&buf->priority);
62 mutex_lock(&buf->lock);
63}
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}
77
78/**
Peter Hurley7bfe0b72013-06-15 09:36:08 -040079 * tty_buffer_space_avail - return unused buffer space
80 * @port - tty_port owning the flip buffer
81 *
82 * Returns the # of bytes which can be written by the driver without
83 * reaching the buffer limit.
84 *
85 * Note: this does not guarantee that memory is available to write
86 * the returned # of bytes (use tty_prepare_flip_string_xxx() to
87 * pre-allocate if memory guarantee is required).
88 */
89
90int tty_buffer_space_avail(struct tty_port *port)
91{
92 int space = TTYB_MEM_LIMIT - atomic_read(&port->buf.memory_used);
93 return max(space, 0);
94}
95
Peter Hurley9dd51392013-06-15 09:36:03 -040096static void tty_buffer_reset(struct tty_buffer *p, size_t size)
97{
98 p->used = 0;
99 p->size = size;
100 p->next = NULL;
101 p->commit = 0;
102 p->read = 0;
103}
104
Alan Coxe0495732008-10-13 10:36:58 +0100105/**
106 * tty_buffer_free_all - free buffers used by a tty
107 * @tty: tty to free from
108 *
109 * Remove all the buffers pending on a tty whether queued with data
110 * or in the free ring. Must be called when the tty is no longer in use
Alan Coxe0495732008-10-13 10:36:58 +0100111 */
112
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200113void tty_buffer_free_all(struct tty_port *port)
Alan Coxe0495732008-10-13 10:36:58 +0100114{
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200115 struct tty_bufhead *buf = &port->buf;
Peter Hurley809850b2013-06-15 09:36:06 -0400116 struct tty_buffer *p, *next;
117 struct llist_node *llist;
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200118
Peter Hurley2cf7b672013-06-15 09:36:05 -0400119 while ((p = buf->head) != NULL) {
120 buf->head = p->next;
Peter Hurley7391ee12013-06-15 09:36:07 -0400121 if (p->size > 0)
122 kfree(p);
Alan Coxe0495732008-10-13 10:36:58 +0100123 }
Peter Hurley809850b2013-06-15 09:36:06 -0400124 llist = llist_del_all(&buf->free);
125 llist_for_each_entry_safe(p, next, llist, free)
Peter Hurley2cf7b672013-06-15 09:36:05 -0400126 kfree(p);
Peter Hurley809850b2013-06-15 09:36:06 -0400127
Peter Hurley7391ee12013-06-15 09:36:07 -0400128 tty_buffer_reset(&buf->sentinel, 0);
129 buf->head = &buf->sentinel;
130 buf->tail = &buf->sentinel;
Peter Hurley7bfe0b72013-06-15 09:36:08 -0400131
132 atomic_set(&buf->memory_used, 0);
Alan Coxe0495732008-10-13 10:36:58 +0100133}
134
135/**
136 * tty_buffer_alloc - allocate a tty buffer
137 * @tty: tty device
138 * @size: desired size (characters)
139 *
140 * Allocate a new tty buffer to hold the desired number of characters.
Peter Hurley11b9faa2013-06-15 09:36:04 -0400141 * We round our buffers off in 256 character chunks to get better
142 * allocation behaviour.
Alan Coxe0495732008-10-13 10:36:58 +0100143 * Return NULL if out of memory or the allocation would exceed the
144 * per device queue
Alan Coxe0495732008-10-13 10:36:58 +0100145 */
146
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200147static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
Alan Coxe0495732008-10-13 10:36:58 +0100148{
Peter Hurley809850b2013-06-15 09:36:06 -0400149 struct llist_node *free;
Alan Coxe0495732008-10-13 10:36:58 +0100150 struct tty_buffer *p;
151
Peter Hurley11b9faa2013-06-15 09:36:04 -0400152 /* Round the buffer size out */
153 size = __ALIGN_MASK(size, TTYB_ALIGN_MASK);
154
155 if (size <= MIN_TTYB_SIZE) {
Peter Hurley809850b2013-06-15 09:36:06 -0400156 free = llist_del_first(&port->buf.free);
157 if (free) {
158 p = llist_entry(free, struct tty_buffer, free);
Peter Hurley11b9faa2013-06-15 09:36:04 -0400159 goto found;
160 }
161 }
162
163 /* Should possibly check if this fails for the largest buffer we
164 have queued and recycle that ? */
Peter Hurley7bfe0b72013-06-15 09:36:08 -0400165 if (atomic_read(&port->buf.memory_used) > TTYB_MEM_LIMIT)
Alan Coxe0495732008-10-13 10:36:58 +0100166 return NULL;
167 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
168 if (p == NULL)
169 return NULL;
Peter Hurley9dd51392013-06-15 09:36:03 -0400170
Peter Hurley11b9faa2013-06-15 09:36:04 -0400171found:
Peter Hurley9dd51392013-06-15 09:36:03 -0400172 tty_buffer_reset(p, size);
Peter Hurley7bfe0b72013-06-15 09:36:08 -0400173 atomic_add(size, &port->buf.memory_used);
Alan Coxe0495732008-10-13 10:36:58 +0100174 return p;
175}
176
177/**
178 * tty_buffer_free - free a tty buffer
179 * @tty: tty owning the buffer
180 * @b: the buffer to free
181 *
182 * Free a tty buffer, or add it to the free list according to our
183 * internal strategy
Alan Coxe0495732008-10-13 10:36:58 +0100184 */
185
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200186static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b)
Alan Coxe0495732008-10-13 10:36:58 +0100187{
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200188 struct tty_bufhead *buf = &port->buf;
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200189
Alan Coxe0495732008-10-13 10:36:58 +0100190 /* Dumb strategy for now - should keep some stats */
Peter Hurley7bfe0b72013-06-15 09:36:08 -0400191 WARN_ON(atomic_sub_return(b->size, &buf->memory_used) < 0);
Alan Coxe0495732008-10-13 10:36:58 +0100192
Peter Hurley1cef50e2013-06-15 09:36:02 -0400193 if (b->size > MIN_TTYB_SIZE)
Alan Coxe0495732008-10-13 10:36:58 +0100194 kfree(b);
Peter Hurley7391ee12013-06-15 09:36:07 -0400195 else if (b->size > 0)
Peter Hurley809850b2013-06-15 09:36:06 -0400196 llist_add(&b->free, &buf->free);
Alan Coxe0495732008-10-13 10:36:58 +0100197}
198
199/**
Alan Coxe0495732008-10-13 10:36:58 +0100200 * tty_buffer_flush - flush full tty buffers
201 * @tty: tty to flush
202 *
203 * flush all the buffers containing receive data. If the buffer is
204 * being processed by flush_to_ldisc then we defer the processing
205 * to that function
206 *
Peter Hurleya7c8d582013-06-15 09:36:15 -0400207 * Locking: takes buffer lock to ensure single-threaded flip buffer
Peter Hurleye9975fd2013-06-15 09:36:10 -0400208 * 'consumer'
Alan Coxe0495732008-10-13 10:36:58 +0100209 */
210
211void tty_buffer_flush(struct tty_struct *tty)
212{
Jiri Slaby2fc20662012-10-18 22:26:44 +0200213 struct tty_port *port = tty->port;
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200214 struct tty_bufhead *buf = &port->buf;
Peter Hurley47aa6582013-06-15 09:36:14 -0400215 struct tty_buffer *next;
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200216
Peter Hurleya7c8d582013-06-15 09:36:15 -0400217 atomic_inc(&buf->priority);
Peter Hurleye9975fd2013-06-15 09:36:10 -0400218
Peter Hurleya7c8d582013-06-15 09:36:15 -0400219 mutex_lock(&buf->lock);
Peter Hurley47aa6582013-06-15 09:36:14 -0400220 while ((next = buf->head->next) != NULL) {
221 tty_buffer_free(port, buf->head);
222 buf->head = next;
223 }
224 buf->head->read = buf->head->commit;
Peter Hurleya7c8d582013-06-15 09:36:15 -0400225 atomic_dec(&buf->priority);
226 mutex_unlock(&buf->lock);
Alan Coxe0495732008-10-13 10:36:58 +0100227}
228
229/**
Ilya Zykov64325a32013-01-19 18:16:20 +0400230 * tty_buffer_request_room - grow tty buffer if needed
Alan Coxe0495732008-10-13 10:36:58 +0100231 * @tty: tty structure
232 * @size: size desired
233 *
234 * Make at least size bytes of linear space available for the tty
235 * buffer. If we fail return the size we managed to find.
Alan Coxe0495732008-10-13 10:36:58 +0100236 */
Ilya Zykov64325a32013-01-19 18:16:20 +0400237int tty_buffer_request_room(struct tty_port *port, size_t size)
Alan Coxe0495732008-10-13 10:36:58 +0100238{
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200239 struct tty_bufhead *buf = &port->buf;
Alan Coxe0495732008-10-13 10:36:58 +0100240 struct tty_buffer *b, *n;
241 int left;
Peter Hurleye8437d72013-06-15 09:36:09 -0400242
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200243 b = buf->tail;
Peter Hurley7391ee12013-06-15 09:36:07 -0400244 left = b->size - b->used;
Alan Coxe0495732008-10-13 10:36:58 +0100245
246 if (left < size) {
247 /* This is the slow path - looking for new buffers to use */
Peter Hurley11b9faa2013-06-15 09:36:04 -0400248 if ((n = tty_buffer_alloc(port, size)) != NULL) {
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200249 buf->tail = n;
Peter Hurleye8437d72013-06-15 09:36:09 -0400250 b->commit = b->used;
251 smp_mb();
252 b->next = n;
Alan Coxe0495732008-10-13 10:36:58 +0100253 } else
254 size = left;
255 }
Alan Coxe0495732008-10-13 10:36:58 +0100256 return size;
257}
258EXPORT_SYMBOL_GPL(tty_buffer_request_room);
259
260/**
Alan Cox2832fc12010-02-18 16:43:54 +0000261 * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer
Jiri Slaby2f693352013-01-03 15:53:02 +0100262 * @port: tty port
Alan Coxe0495732008-10-13 10:36:58 +0100263 * @chars: characters
Alan Cox2832fc12010-02-18 16:43:54 +0000264 * @flag: flag value for each character
Alan Coxe0495732008-10-13 10:36:58 +0100265 * @size: size
266 *
267 * Queue a series of bytes to the tty buffering. All the characters
Johan Hovoldccc5ca82010-05-07 19:58:32 +0200268 * passed are marked with the supplied flag. Returns the number added.
Alan Coxe0495732008-10-13 10:36:58 +0100269 */
270
Jiri Slaby2f693352013-01-03 15:53:02 +0100271int tty_insert_flip_string_fixed_flag(struct tty_port *port,
Alan Cox2832fc12010-02-18 16:43:54 +0000272 const unsigned char *chars, char flag, size_t size)
Alan Coxe0495732008-10-13 10:36:58 +0100273{
274 int copied = 0;
275 do {
Fang Wenqid4bee0a2010-03-09 18:54:28 +0800276 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
Ilya Zykov64325a32013-01-19 18:16:20 +0400277 int space = tty_buffer_request_room(port, goal);
278 struct tty_buffer *tb = port->buf.tail;
Peter Hurley7391ee12013-06-15 09:36:07 -0400279 if (unlikely(space == 0))
Alan Coxe0495732008-10-13 10:36:58 +0100280 break;
Peter Hurley1fc359f2013-06-15 09:36:01 -0400281 memcpy(char_buf_ptr(tb, tb->used), chars, space);
282 memset(flag_buf_ptr(tb, tb->used), flag, space);
Alan Coxe0495732008-10-13 10:36:58 +0100283 tb->used += space;
284 copied += space;
285 chars += space;
286 /* There is a small chance that we need to split the data over
287 several buffers. If this is the case we must loop */
288 } while (unlikely(size > copied));
289 return copied;
290}
Alan Cox2832fc12010-02-18 16:43:54 +0000291EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
Alan Coxe0495732008-10-13 10:36:58 +0100292
293/**
294 * tty_insert_flip_string_flags - Add characters to the tty buffer
Jiri Slaby2f693352013-01-03 15:53:02 +0100295 * @port: tty port
Alan Coxe0495732008-10-13 10:36:58 +0100296 * @chars: characters
297 * @flags: flag bytes
298 * @size: size
299 *
300 * Queue a series of bytes to the tty buffering. For each character
301 * the flags array indicates the status of the character. Returns the
302 * number added.
Alan Coxe0495732008-10-13 10:36:58 +0100303 */
304
Jiri Slaby2f693352013-01-03 15:53:02 +0100305int tty_insert_flip_string_flags(struct tty_port *port,
Alan Coxe0495732008-10-13 10:36:58 +0100306 const unsigned char *chars, const char *flags, size_t size)
307{
308 int copied = 0;
309 do {
Fang Wenqid4bee0a2010-03-09 18:54:28 +0800310 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
Ilya Zykov64325a32013-01-19 18:16:20 +0400311 int space = tty_buffer_request_room(port, goal);
312 struct tty_buffer *tb = port->buf.tail;
Peter Hurley7391ee12013-06-15 09:36:07 -0400313 if (unlikely(space == 0))
Alan Coxe0495732008-10-13 10:36:58 +0100314 break;
Peter Hurley1fc359f2013-06-15 09:36:01 -0400315 memcpy(char_buf_ptr(tb, tb->used), chars, space);
316 memcpy(flag_buf_ptr(tb, tb->used), flags, space);
Alan Coxe0495732008-10-13 10:36:58 +0100317 tb->used += space;
318 copied += space;
319 chars += space;
320 flags += space;
321 /* There is a small chance that we need to split the data over
322 several buffers. If this is the case we must loop */
323 } while (unlikely(size > copied));
324 return copied;
325}
326EXPORT_SYMBOL(tty_insert_flip_string_flags);
327
328/**
329 * tty_schedule_flip - push characters to ldisc
Jiri Slaby6732c8b2013-01-03 15:53:07 +0100330 * @port: tty port to push from
Alan Coxe0495732008-10-13 10:36:58 +0100331 *
332 * Takes any pending buffers and transfers their ownership to the
333 * ldisc side of the queue. It then schedules those characters for
334 * processing by the line discipline.
Ivo Siebencee4ad12012-09-27 14:02:05 +0200335 * Note that this function can only be used when the low_latency flag
336 * is unset. Otherwise the workqueue won't be flushed.
Alan Coxe0495732008-10-13 10:36:58 +0100337 */
338
Jiri Slaby6732c8b2013-01-03 15:53:07 +0100339void tty_schedule_flip(struct tty_port *port)
Alan Coxe0495732008-10-13 10:36:58 +0100340{
Jiri Slaby6732c8b2013-01-03 15:53:07 +0100341 struct tty_bufhead *buf = &port->buf;
Jiri Slaby6732c8b2013-01-03 15:53:07 +0100342 WARN_ON(port->low_latency);
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200343
Peter Hurley7391ee12013-06-15 09:36:07 -0400344 buf->tail->commit = buf->tail->used;
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200345 schedule_work(&buf->work);
Alan Coxe0495732008-10-13 10:36:58 +0100346}
347EXPORT_SYMBOL(tty_schedule_flip);
348
349/**
350 * tty_prepare_flip_string - make room for characters
Jiri Slaby2f693352013-01-03 15:53:02 +0100351 * @port: tty port
Alan Coxe0495732008-10-13 10:36:58 +0100352 * @chars: return pointer for character write area
353 * @size: desired size
354 *
355 * Prepare a block of space in the buffer for data. Returns the length
356 * available and buffer pointer to the space which is now allocated and
357 * accounted for as ready for normal characters. This is used for drivers
358 * that need their own block copy routines into the buffer. There is no
359 * guarantee the buffer is a DMA target!
Alan Coxe0495732008-10-13 10:36:58 +0100360 */
361
Jiri Slaby2f693352013-01-03 15:53:02 +0100362int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars,
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200363 size_t size)
Alan Coxe0495732008-10-13 10:36:58 +0100364{
Ilya Zykov64325a32013-01-19 18:16:20 +0400365 int space = tty_buffer_request_room(port, size);
Alan Coxe0495732008-10-13 10:36:58 +0100366 if (likely(space)) {
Ilya Zykov64325a32013-01-19 18:16:20 +0400367 struct tty_buffer *tb = port->buf.tail;
Peter Hurley1fc359f2013-06-15 09:36:01 -0400368 *chars = char_buf_ptr(tb, tb->used);
369 memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
Alan Coxe0495732008-10-13 10:36:58 +0100370 tb->used += space;
371 }
372 return space;
373}
374EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
375
376/**
377 * tty_prepare_flip_string_flags - make room for characters
Jiri Slaby2f693352013-01-03 15:53:02 +0100378 * @port: tty port
Alan Coxe0495732008-10-13 10:36:58 +0100379 * @chars: return pointer for character write area
380 * @flags: return pointer for status flag write area
381 * @size: desired size
382 *
383 * Prepare a block of space in the buffer for data. Returns the length
384 * available and buffer pointer to the space which is now allocated and
385 * accounted for as ready for characters. This is used for drivers
386 * that need their own block copy routines into the buffer. There is no
387 * guarantee the buffer is a DMA target!
Alan Coxe0495732008-10-13 10:36:58 +0100388 */
389
Jiri Slaby2f693352013-01-03 15:53:02 +0100390int tty_prepare_flip_string_flags(struct tty_port *port,
Alan Coxe0495732008-10-13 10:36:58 +0100391 unsigned char **chars, char **flags, size_t size)
392{
Ilya Zykov64325a32013-01-19 18:16:20 +0400393 int space = tty_buffer_request_room(port, size);
Alan Coxe0495732008-10-13 10:36:58 +0100394 if (likely(space)) {
Ilya Zykov64325a32013-01-19 18:16:20 +0400395 struct tty_buffer *tb = port->buf.tail;
Peter Hurley1fc359f2013-06-15 09:36:01 -0400396 *chars = char_buf_ptr(tb, tb->used);
397 *flags = flag_buf_ptr(tb, tb->used);
Alan Coxe0495732008-10-13 10:36:58 +0100398 tb->used += space;
399 }
400 return space;
401}
402EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
403
404
Peter Hurleyda261e72013-06-15 09:14:14 -0400405static int
406receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
407{
408 struct tty_ldisc *disc = tty->ldisc;
Peter Hurley1fc359f2013-06-15 09:36:01 -0400409 unsigned char *p = char_buf_ptr(head, head->read);
410 char *f = flag_buf_ptr(head, head->read);
Peter Hurleyda261e72013-06-15 09:14:14 -0400411
Peter Hurley24a89d12013-06-15 09:14:15 -0400412 if (disc->ops->receive_buf2)
413 count = disc->ops->receive_buf2(tty, p, f, count);
414 else {
415 count = min_t(int, count, tty->receive_room);
416 if (count)
417 disc->ops->receive_buf(tty, p, f, count);
418 }
Peter Hurleyda261e72013-06-15 09:14:14 -0400419 head->read += count;
420 return count;
421}
Alan Coxe0495732008-10-13 10:36:58 +0100422
423/**
424 * flush_to_ldisc
425 * @work: tty structure passed from work queue.
426 *
427 * This routine is called out of the software interrupt to flush data
428 * from the buffer chain to the line discipline.
429 *
Peter Hurleye9975fd2013-06-15 09:36:10 -0400430 * The receive_buf method is single threaded for each tty instance.
431 *
Peter Hurleya7c8d582013-06-15 09:36:15 -0400432 * Locking: takes buffer lock to ensure single-threaded flip buffer
Peter Hurleye9975fd2013-06-15 09:36:10 -0400433 * 'consumer'
Alan Coxe0495732008-10-13 10:36:58 +0100434 */
435
436static void flush_to_ldisc(struct work_struct *work)
437{
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200438 struct tty_port *port = container_of(work, struct tty_port, buf.work);
439 struct tty_bufhead *buf = &port->buf;
440 struct tty_struct *tty;
Alan Coxe0495732008-10-13 10:36:58 +0100441 struct tty_ldisc *disc;
Alan Coxe0495732008-10-13 10:36:58 +0100442
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200443 tty = port->itty;
Jiri Slaby34dcfb82013-02-27 22:30:24 +0100444 if (tty == NULL)
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200445 return;
446
Alan Coxe0495732008-10-13 10:36:58 +0100447 disc = tty_ldisc_ref(tty);
Peter Hurley36697522013-06-15 07:04:48 -0400448 if (disc == NULL)
Alan Coxe0495732008-10-13 10:36:58 +0100449 return;
450
Peter Hurleya7c8d582013-06-15 09:36:15 -0400451 mutex_lock(&buf->lock);
Linus Torvalds45242002009-10-14 08:59:49 -0700452
Peter Hurleyd7a68be2013-06-15 09:36:11 -0400453 while (1) {
454 struct tty_buffer *head = buf->head;
455 int count;
Linus Torvalds45242002009-10-14 08:59:49 -0700456
Peter Hurleya7c8d582013-06-15 09:36:15 -0400457 /* Ldisc or user is trying to gain exclusive access */
458 if (atomic_read(&buf->priority))
Peter Hurleyd7a68be2013-06-15 09:36:11 -0400459 break;
Peter Hurleye9975fd2013-06-15 09:36:10 -0400460
Peter Hurleyd7a68be2013-06-15 09:36:11 -0400461 count = head->commit - head->read;
462 if (!count) {
463 if (head->next == NULL)
Peter Hurley39f610e2013-03-20 13:20:43 -0400464 break;
Peter Hurleyd7a68be2013-06-15 09:36:11 -0400465 buf->head = head->next;
466 tty_buffer_free(port, head);
467 continue;
Alan Coxe0495732008-10-13 10:36:58 +0100468 }
Peter Hurleyd7a68be2013-06-15 09:36:11 -0400469
470 count = receive_buf(tty, head, count);
471 if (!count)
472 break;
Alan Coxe0495732008-10-13 10:36:58 +0100473 }
Linus Torvalds45242002009-10-14 08:59:49 -0700474
Peter Hurleya7c8d582013-06-15 09:36:15 -0400475 mutex_unlock(&buf->lock);
Alan Coxe0495732008-10-13 10:36:58 +0100476
477 tty_ldisc_deref(disc);
478}
479
480/**
OGAWA Hirofumie043e422009-07-29 12:15:56 -0700481 * tty_flush_to_ldisc
482 * @tty: tty to push
483 *
484 * Push the terminal flip buffers to the line discipline.
485 *
486 * Must not be called from IRQ context.
487 */
488void tty_flush_to_ldisc(struct tty_struct *tty)
489{
Jiri Slabyd6c53c02013-01-03 15:53:05 +0100490 if (!tty->port->low_latency)
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200491 flush_work(&tty->port->buf.work);
OGAWA Hirofumie043e422009-07-29 12:15:56 -0700492}
493
494/**
Alan Coxe0495732008-10-13 10:36:58 +0100495 * tty_flip_buffer_push - terminal
Jiri Slaby2e124b42013-01-03 15:53:06 +0100496 * @port: tty port to push
Alan Coxe0495732008-10-13 10:36:58 +0100497 *
498 * Queue a push of the terminal flip buffers to the line discipline. This
Jiri Slabyd6c53c02013-01-03 15:53:05 +0100499 * function must not be called from IRQ context if port->low_latency is
500 * set.
Alan Coxe0495732008-10-13 10:36:58 +0100501 *
502 * In the event of the queue being busy for flipping the work will be
503 * held off and retried later.
Alan Coxe0495732008-10-13 10:36:58 +0100504 */
505
Jiri Slaby2e124b42013-01-03 15:53:06 +0100506void tty_flip_buffer_push(struct tty_port *port)
Alan Coxe0495732008-10-13 10:36:58 +0100507{
Jiri Slaby2e124b42013-01-03 15:53:06 +0100508 struct tty_bufhead *buf = &port->buf;
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200509
Peter Hurley7391ee12013-06-15 09:36:07 -0400510 buf->tail->commit = buf->tail->used;
Alan Coxe0495732008-10-13 10:36:58 +0100511
Jiri Slaby2e124b42013-01-03 15:53:06 +0100512 if (port->low_latency)
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200513 flush_to_ldisc(&buf->work);
Alan Coxe0495732008-10-13 10:36:58 +0100514 else
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200515 schedule_work(&buf->work);
Alan Coxe0495732008-10-13 10:36:58 +0100516}
517EXPORT_SYMBOL(tty_flip_buffer_push);
518
519/**
520 * tty_buffer_init - prepare a tty buffer structure
521 * @tty: tty to initialise
522 *
523 * Set up the initial state of the buffer management for a tty device.
524 * Must be called before the other tty buffer functions are used.
Alan Coxe0495732008-10-13 10:36:58 +0100525 */
526
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200527void tty_buffer_init(struct tty_port *port)
Alan Coxe0495732008-10-13 10:36:58 +0100528{
Jiri Slabyecbbfd42012-10-18 22:26:47 +0200529 struct tty_bufhead *buf = &port->buf;
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200530
Peter Hurleya7c8d582013-06-15 09:36:15 -0400531 mutex_init(&buf->lock);
Peter Hurley7391ee12013-06-15 09:36:07 -0400532 tty_buffer_reset(&buf->sentinel, 0);
533 buf->head = &buf->sentinel;
534 buf->tail = &buf->sentinel;
Peter Hurley809850b2013-06-15 09:36:06 -0400535 init_llist_head(&buf->free);
Peter Hurley7bfe0b72013-06-15 09:36:08 -0400536 atomic_set(&buf->memory_used, 0);
Peter Hurleya7c8d582013-06-15 09:36:15 -0400537 atomic_set(&buf->priority, 0);
Jiri Slaby5cff39c2012-10-18 22:26:45 +0200538 INIT_WORK(&buf->work, flush_to_ldisc);
Alan Coxe0495732008-10-13 10:36:58 +0100539}