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 */
snd_seq_fifo_new(int poolsize)18 struct 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(f);
29 return NULL;
30 }
31 if (snd_seq_pool_init(f->pool) < 0) {
32 snd_seq_pool_delete(&f->pool);
33 kfree(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(&f->overflow, 0);
41
42 f->head = NULL;
43 f->tail = NULL;
44 f->cells = 0;
45
46 return f;
47 }
48
snd_seq_fifo_delete(struct snd_seq_fifo ** fifo)49 void 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(f->pool);
62
63 snd_seq_fifo_clear(f);
64
65 /* wake up clients if any */
66 if (waitqueue_active(&f->input_sleep))
67 wake_up(&f->input_sleep);
68
69 /* release resources...*/
70 /*....................*/
71
72 if (f->pool) {
73 snd_seq_pool_done(f->pool);
74 snd_seq_pool_delete(&f->pool);
75 }
76
77 kfree(f);
78 }
79
80 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
81
82 /* clear queue */
snd_seq_fifo_clear(struct snd_seq_fifo * f)83 void 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(&f->overflow, 0);
89
90 snd_use_lock_sync(&f->use_lock);
91 spin_lock_irq(&f->lock);
92 /* drain the fifo */
93 while ((cell = fifo_cell_out(f)) != NULL) {
94 snd_seq_cell_free(cell);
95 }
96 spin_unlock_irq(&f->lock);
97 }
98
99
100 /* enqueue event to fifo */
snd_seq_fifo_event_in(struct snd_seq_fifo * f,struct snd_seq_event * event)101 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
102 struct snd_seq_event *event)
103 {
104 struct snd_seq_event_cell *cell;
105 unsigned long flags;
106 int err;
107
108 if (snd_BUG_ON(!f))
109 return -EINVAL;
110
111 snd_use_lock_use(&f->use_lock);
112 err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL, NULL); /* always non-blocking */
113 if (err < 0) {
114 if ((err == -ENOMEM) || (err == -EAGAIN))
115 atomic_inc(&f->overflow);
116 snd_use_lock_free(&f->use_lock);
117 return err;
118 }
119
120 /* append new cells to fifo */
121 spin_lock_irqsave(&f->lock, flags);
122 if (f->tail != NULL)
123 f->tail->next = cell;
124 f->tail = cell;
125 if (f->head == NULL)
126 f->head = cell;
127 cell->next = NULL;
128 f->cells++;
129 spin_unlock_irqrestore(&f->lock, flags);
130
131 /* wakeup client */
132 if (waitqueue_active(&f->input_sleep))
133 wake_up(&f->input_sleep);
134
135 snd_use_lock_free(&f->use_lock);
136
137 return 0; /* success */
138
139 }
140
141 /* dequeue cell from fifo */
fifo_cell_out(struct snd_seq_fifo * f)142 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
143 {
144 struct snd_seq_event_cell *cell;
145
146 if ((cell = f->head) != NULL) {
147 f->head = cell->next;
148
149 /* reset tail if this was the last element */
150 if (f->tail == cell)
151 f->tail = NULL;
152
153 cell->next = NULL;
154 f->cells--;
155 }
156
157 return cell;
158 }
159
160 /* dequeue cell from fifo and copy on user space */
snd_seq_fifo_cell_out(struct snd_seq_fifo * f,struct snd_seq_event_cell ** cellp,int nonblock)161 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
162 struct snd_seq_event_cell **cellp, int nonblock)
163 {
164 struct snd_seq_event_cell *cell;
165 unsigned long flags;
166 wait_queue_entry_t wait;
167
168 if (snd_BUG_ON(!f))
169 return -EINVAL;
170
171 *cellp = NULL;
172 init_waitqueue_entry(&wait, current);
173 spin_lock_irqsave(&f->lock, flags);
174 while ((cell = fifo_cell_out(f)) == NULL) {
175 if (nonblock) {
176 /* non-blocking - return immediately */
177 spin_unlock_irqrestore(&f->lock, flags);
178 return -EAGAIN;
179 }
180 set_current_state(TASK_INTERRUPTIBLE);
181 add_wait_queue(&f->input_sleep, &wait);
182 spin_unlock_irqrestore(&f->lock, flags);
183 schedule();
184 spin_lock_irqsave(&f->lock, flags);
185 remove_wait_queue(&f->input_sleep, &wait);
186 if (signal_pending(current)) {
187 spin_unlock_irqrestore(&f->lock, flags);
188 return -ERESTARTSYS;
189 }
190 }
191 spin_unlock_irqrestore(&f->lock, flags);
192 *cellp = cell;
193
194 return 0;
195 }
196
197
snd_seq_fifo_cell_putback(struct snd_seq_fifo * f,struct snd_seq_event_cell * cell)198 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
199 struct snd_seq_event_cell *cell)
200 {
201 unsigned long flags;
202
203 if (cell) {
204 spin_lock_irqsave(&f->lock, flags);
205 cell->next = f->head;
206 f->head = cell;
207 if (!f->tail)
208 f->tail = cell;
209 f->cells++;
210 spin_unlock_irqrestore(&f->lock, flags);
211 }
212 }
213
214
215 /* polling; return non-zero if queue is available */
snd_seq_fifo_poll_wait(struct snd_seq_fifo * f,struct file * file,poll_table * wait)216 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
217 poll_table *wait)
218 {
219 poll_wait(file, &f->input_sleep, wait);
220 return (f->cells > 0);
221 }
222
223 /* change the size of pool; all old events are removed */
snd_seq_fifo_resize(struct snd_seq_fifo * f,int poolsize)224 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
225 {
226 struct snd_seq_pool *newpool, *oldpool;
227 struct snd_seq_event_cell *cell, *next, *oldhead;
228
229 if (snd_BUG_ON(!f || !f->pool))
230 return -EINVAL;
231
232 /* allocate new pool */
233 newpool = snd_seq_pool_new(poolsize);
234 if (newpool == NULL)
235 return -ENOMEM;
236 if (snd_seq_pool_init(newpool) < 0) {
237 snd_seq_pool_delete(&newpool);
238 return -ENOMEM;
239 }
240
241 spin_lock_irq(&f->lock);
242 /* remember old pool */
243 oldpool = f->pool;
244 oldhead = f->head;
245 /* exchange pools */
246 f->pool = newpool;
247 f->head = NULL;
248 f->tail = NULL;
249 f->cells = 0;
250 /* NOTE: overflow flag is not cleared */
251 spin_unlock_irq(&f->lock);
252
253 /* close the old pool and wait until all users are gone */
254 snd_seq_pool_mark_closing(oldpool);
255 snd_use_lock_sync(&f->use_lock);
256
257 /* release cells in old pool */
258 for (cell = oldhead; cell; cell = next) {
259 next = cell->next;
260 snd_seq_cell_free(cell);
261 }
262 snd_seq_pool_delete(&oldpool);
263
264 return 0;
265 }
266
267 /* get the number of unused cells safely */
snd_seq_fifo_unused_cells(struct snd_seq_fifo * f)268 int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f)
269 {
270 unsigned long flags;
271 int cells;
272
273 if (!f)
274 return 0;
275
276 snd_use_lock_use(&f->use_lock);
277 spin_lock_irqsave(&f->lock, flags);
278 cells = snd_seq_unused_cells(f->pool);
279 spin_unlock_irqrestore(&f->lock, flags);
280 snd_use_lock_free(&f->use_lock);
281 return cells;
282 }
283