1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ALSA sequencer FIFO
4 * Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
5 */
6
7#include <sound/core.h>
8#include <linux/slab.h>
9#include <linux/sched/signal.h>
10
11#include "seq_fifo.h"
12#include "seq_lock.h"
13
14
15/* FIFO */
16
17/* create new fifo */
18struct snd_seq_fifo *snd_seq_fifo_new(int poolsize)
19{
20 struct snd_seq_fifo *f;
21
22 f = kzalloc(sizeof(*f), GFP_KERNEL);
23 if (!f)
24 return NULL;
25
26 f->pool = snd_seq_pool_new(poolsize);
27 if (f->pool == NULL) {
28 kfree(objp: f);
29 return NULL;
30 }
31 if (snd_seq_pool_init(pool: f->pool) < 0) {
32 snd_seq_pool_delete(pool: &f->pool);
33 kfree(objp: f);
34 return NULL;
35 }
36
37 spin_lock_init(&f->lock);
38 snd_use_lock_init(&f->use_lock);
39 init_waitqueue_head(&f->input_sleep);
40 atomic_set(v: &f->overflow, i: 0);
41
42 f->head = NULL;
43 f->tail = NULL;
44 f->cells = 0;
45
46 return f;
47}
48
49void snd_seq_fifo_delete(struct snd_seq_fifo **fifo)
50{
51 struct snd_seq_fifo *f;
52
53 if (snd_BUG_ON(!fifo))
54 return;
55 f = *fifo;
56 if (snd_BUG_ON(!f))
57 return;
58 *fifo = NULL;
59
60 if (f->pool)
61 snd_seq_pool_mark_closing(pool: f->pool);
62
63 snd_seq_fifo_clear(f);
64
65 /* wake up clients if any */
66 if (waitqueue_active(wq_head: &f->input_sleep))
67 wake_up(&f->input_sleep);
68
69 /* release resources...*/
70 /*....................*/
71
72 if (f->pool) {
73 snd_seq_pool_done(pool: f->pool);
74 snd_seq_pool_delete(pool: &f->pool);
75 }
76
77 kfree(objp: f);
78}
79
80static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
81
82/* clear queue */
83void snd_seq_fifo_clear(struct snd_seq_fifo *f)
84{
85 struct snd_seq_event_cell *cell;
86
87 /* clear overflow flag */
88 atomic_set(v: &f->overflow, i: 0);
89
90 snd_use_lock_sync(&f->use_lock);
91 guard(spinlock_irq)(l: &f->lock);
92 /* drain the fifo */
93 while ((cell = fifo_cell_out(f)) != NULL) {
94 snd_seq_cell_free(cell);
95 }
96}
97
98
99/* enqueue event to fifo */
100int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
101 struct snd_seq_event *event)
102{
103 struct snd_seq_event_cell *cell;
104 int err;
105
106 if (snd_BUG_ON(!f))
107 return -EINVAL;
108
109 guard(snd_seq_fifo)(T: f);
110 err = snd_seq_event_dup(pool: f->pool, event, cellp: &cell, nonblock: 1, NULL, NULL); /* always non-blocking */
111 if (err < 0) {
112 if ((err == -ENOMEM) || (err == -EAGAIN))
113 atomic_inc(v: &f->overflow);
114 return err;
115 }
116
117 /* append new cells to fifo */
118 scoped_guard(spinlock_irqsave, &f->lock) {
119 if (f->tail != NULL)
120 f->tail->next = cell;
121 f->tail = cell;
122 if (f->head == NULL)
123 f->head = cell;
124 cell->next = NULL;
125 f->cells++;
126 }
127
128 /* wakeup client */
129 if (waitqueue_active(wq_head: &f->input_sleep))
130 wake_up(&f->input_sleep);
131
132 return 0; /* success */
133
134}
135
136/* dequeue cell from fifo */
137static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
138{
139 struct snd_seq_event_cell *cell;
140
141 cell = f->head;
142 if (cell) {
143 f->head = cell->next;
144
145 /* reset tail if this was the last element */
146 if (f->tail == cell)
147 f->tail = NULL;
148
149 cell->next = NULL;
150 f->cells--;
151 }
152
153 return cell;
154}
155
156/* dequeue cell from fifo and copy on user space */
157int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
158 struct snd_seq_event_cell **cellp, int nonblock)
159{
160 struct snd_seq_event_cell *cell;
161 unsigned long flags;
162 wait_queue_entry_t wait;
163
164 if (snd_BUG_ON(!f))
165 return -EINVAL;
166
167 *cellp = NULL;
168 init_waitqueue_entry(wq_entry: &wait, current);
169 spin_lock_irqsave(&f->lock, flags);
170 while ((cell = fifo_cell_out(f)) == NULL) {
171 if (nonblock) {
172 /* non-blocking - return immediately */
173 spin_unlock_irqrestore(lock: &f->lock, flags);
174 return -EAGAIN;
175 }
176 set_current_state(TASK_INTERRUPTIBLE);
177 add_wait_queue(wq_head: &f->input_sleep, wq_entry: &wait);
178 spin_unlock_irqrestore(lock: &f->lock, flags);
179 schedule();
180 spin_lock_irqsave(&f->lock, flags);
181 remove_wait_queue(wq_head: &f->input_sleep, wq_entry: &wait);
182 if (signal_pending(current)) {
183 spin_unlock_irqrestore(lock: &f->lock, flags);
184 return -ERESTARTSYS;
185 }
186 }
187 spin_unlock_irqrestore(lock: &f->lock, flags);
188 *cellp = cell;
189
190 return 0;
191}
192
193
194void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
195 struct snd_seq_event_cell *cell)
196{
197 if (cell) {
198 guard(spinlock_irqsave)(l: &f->lock);
199 cell->next = f->head;
200 f->head = cell;
201 if (!f->tail)
202 f->tail = cell;
203 f->cells++;
204 }
205}
206
207
208/* polling; return non-zero if queue is available */
209int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
210 poll_table *wait)
211{
212 poll_wait(filp: file, wait_address: &f->input_sleep, p: wait);
213 guard(spinlock_irq)(l: &f->lock);
214 return (f->cells > 0);
215}
216
217/* change the size of pool; all old events are removed */
218int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
219{
220 struct snd_seq_pool *newpool, *oldpool;
221 struct snd_seq_event_cell *cell, *next, *oldhead;
222
223 if (snd_BUG_ON(!f || !f->pool))
224 return -EINVAL;
225
226 /* allocate new pool */
227 newpool = snd_seq_pool_new(poolsize);
228 if (newpool == NULL)
229 return -ENOMEM;
230 if (snd_seq_pool_init(pool: newpool) < 0) {
231 snd_seq_pool_delete(pool: &newpool);
232 return -ENOMEM;
233 }
234
235 scoped_guard(spinlock_irq, &f->lock) {
236 /* remember old pool */
237 oldpool = f->pool;
238 oldhead = f->head;
239 /* exchange pools */
240 f->pool = newpool;
241 f->head = NULL;
242 f->tail = NULL;
243 f->cells = 0;
244 /* NOTE: overflow flag is not cleared */
245 }
246
247 /* close the old pool and wait until all users are gone */
248 snd_seq_pool_mark_closing(pool: oldpool);
249 snd_use_lock_sync(&f->use_lock);
250
251 /* release cells in old pool */
252 for (cell = oldhead; cell; cell = next) {
253 next = cell->next;
254 snd_seq_cell_free(cell);
255 }
256 snd_seq_pool_delete(pool: &oldpool);
257
258 return 0;
259}
260
261/* get the number of unused cells safely */
262int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f)
263{
264 if (!f)
265 return 0;
266
267 guard(snd_seq_fifo)(T: f);
268 guard(spinlock_irqsave)(l: &f->lock);
269 return snd_seq_unused_cells(pool: f->pool);
270}
271

source code of linux/sound/core/seq/seq_fifo.c