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Linux/sound/core/seq/seq_fifo.c

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  1 /*
  2  *   ALSA sequencer FIFO
  3  *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
  4  *
  5  *
  6  *   This program is free software; you can redistribute it and/or modify
  7  *   it under the terms of the GNU General Public License as published by
  8  *   the Free Software Foundation; either version 2 of the License, or
  9  *   (at your option) any later version.
 10  *
 11  *   This program is distributed in the hope that it will be useful,
 12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  *   GNU General Public License for more details.
 15  *
 16  *   You should have received a copy of the GNU General Public License
 17  *   along with this program; if not, write to the Free Software
 18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 19  *
 20  */
 21 
 22 #include <sound/core.h>
 23 #include <linux/slab.h>
 24 #include <linux/sched/signal.h>
 25 
 26 #include "seq_fifo.h"
 27 #include "seq_lock.h"
 28 
 29 
 30 /* FIFO */
 31 
 32 /* create new fifo */
 33 struct snd_seq_fifo *snd_seq_fifo_new(int poolsize)
 34 {
 35         struct snd_seq_fifo *f;
 36 
 37         f = kzalloc(sizeof(*f), GFP_KERNEL);
 38         if (!f)
 39                 return NULL;
 40 
 41         f->pool = snd_seq_pool_new(poolsize);
 42         if (f->pool == NULL) {
 43                 kfree(f);
 44                 return NULL;
 45         }
 46         if (snd_seq_pool_init(f->pool) < 0) {
 47                 snd_seq_pool_delete(&f->pool);
 48                 kfree(f);
 49                 return NULL;
 50         }
 51 
 52         spin_lock_init(&f->lock);
 53         snd_use_lock_init(&f->use_lock);
 54         init_waitqueue_head(&f->input_sleep);
 55         atomic_set(&f->overflow, 0);
 56 
 57         f->head = NULL;
 58         f->tail = NULL;
 59         f->cells = 0;
 60         
 61         return f;
 62 }
 63 
 64 void snd_seq_fifo_delete(struct snd_seq_fifo **fifo)
 65 {
 66         struct snd_seq_fifo *f;
 67 
 68         if (snd_BUG_ON(!fifo))
 69                 return;
 70         f = *fifo;
 71         if (snd_BUG_ON(!f))
 72                 return;
 73         *fifo = NULL;
 74 
 75         if (f->pool)
 76                 snd_seq_pool_mark_closing(f->pool);
 77 
 78         snd_seq_fifo_clear(f);
 79 
 80         /* wake up clients if any */
 81         if (waitqueue_active(&f->input_sleep))
 82                 wake_up(&f->input_sleep);
 83 
 84         /* release resources...*/
 85         /*....................*/
 86 
 87         if (f->pool) {
 88                 snd_seq_pool_done(f->pool);
 89                 snd_seq_pool_delete(&f->pool);
 90         }
 91         
 92         kfree(f);
 93 }
 94 
 95 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
 96 
 97 /* clear queue */
 98 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
 99 {
100         struct snd_seq_event_cell *cell;
101         unsigned long flags;
102 
103         /* clear overflow flag */
104         atomic_set(&f->overflow, 0);
105 
106         snd_use_lock_sync(&f->use_lock);
107         spin_lock_irqsave(&f->lock, flags);
108         /* drain the fifo */
109         while ((cell = fifo_cell_out(f)) != NULL) {
110                 snd_seq_cell_free(cell);
111         }
112         spin_unlock_irqrestore(&f->lock, flags);
113 }
114 
115 
116 /* enqueue event to fifo */
117 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
118                           struct snd_seq_event *event)
119 {
120         struct snd_seq_event_cell *cell;
121         unsigned long flags;
122         int err;
123 
124         if (snd_BUG_ON(!f))
125                 return -EINVAL;
126 
127         snd_use_lock_use(&f->use_lock);
128         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL, NULL); /* always non-blocking */
129         if (err < 0) {
130                 if ((err == -ENOMEM) || (err == -EAGAIN))
131                         atomic_inc(&f->overflow);
132                 snd_use_lock_free(&f->use_lock);
133                 return err;
134         }
135                 
136         /* append new cells to fifo */
137         spin_lock_irqsave(&f->lock, flags);
138         if (f->tail != NULL)
139                 f->tail->next = cell;
140         f->tail = cell;
141         if (f->head == NULL)
142                 f->head = cell;
143         cell->next = NULL;
144         f->cells++;
145         spin_unlock_irqrestore(&f->lock, flags);
146 
147         /* wakeup client */
148         if (waitqueue_active(&f->input_sleep))
149                 wake_up(&f->input_sleep);
150 
151         snd_use_lock_free(&f->use_lock);
152 
153         return 0; /* success */
154 
155 }
156 
157 /* dequeue cell from fifo */
158 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
159 {
160         struct snd_seq_event_cell *cell;
161 
162         if ((cell = f->head) != NULL) {
163                 f->head = cell->next;
164 
165                 /* reset tail if this was the last element */
166                 if (f->tail == cell)
167                         f->tail = NULL;
168 
169                 cell->next = NULL;
170                 f->cells--;
171         }
172 
173         return cell;
174 }
175 
176 /* dequeue cell from fifo and copy on user space */
177 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
178                           struct snd_seq_event_cell **cellp, int nonblock)
179 {
180         struct snd_seq_event_cell *cell;
181         unsigned long flags;
182         wait_queue_entry_t wait;
183 
184         if (snd_BUG_ON(!f))
185                 return -EINVAL;
186 
187         *cellp = NULL;
188         init_waitqueue_entry(&wait, current);
189         spin_lock_irqsave(&f->lock, flags);
190         while ((cell = fifo_cell_out(f)) == NULL) {
191                 if (nonblock) {
192                         /* non-blocking - return immediately */
193                         spin_unlock_irqrestore(&f->lock, flags);
194                         return -EAGAIN;
195                 }
196                 set_current_state(TASK_INTERRUPTIBLE);
197                 add_wait_queue(&f->input_sleep, &wait);
198                 spin_unlock_irq(&f->lock);
199                 schedule();
200                 spin_lock_irq(&f->lock);
201                 remove_wait_queue(&f->input_sleep, &wait);
202                 if (signal_pending(current)) {
203                         spin_unlock_irqrestore(&f->lock, flags);
204                         return -ERESTARTSYS;
205                 }
206         }
207         spin_unlock_irqrestore(&f->lock, flags);
208         *cellp = cell;
209 
210         return 0;
211 }
212 
213 
214 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
215                                struct snd_seq_event_cell *cell)
216 {
217         unsigned long flags;
218 
219         if (cell) {
220                 spin_lock_irqsave(&f->lock, flags);
221                 cell->next = f->head;
222                 f->head = cell;
223                 if (!f->tail)
224                         f->tail = cell;
225                 f->cells++;
226                 spin_unlock_irqrestore(&f->lock, flags);
227         }
228 }
229 
230 
231 /* polling; return non-zero if queue is available */
232 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
233                            poll_table *wait)
234 {
235         poll_wait(file, &f->input_sleep, wait);
236         return (f->cells > 0);
237 }
238 
239 /* change the size of pool; all old events are removed */
240 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
241 {
242         unsigned long flags;
243         struct snd_seq_pool *newpool, *oldpool;
244         struct snd_seq_event_cell *cell, *next, *oldhead;
245 
246         if (snd_BUG_ON(!f || !f->pool))
247                 return -EINVAL;
248 
249         /* allocate new pool */
250         newpool = snd_seq_pool_new(poolsize);
251         if (newpool == NULL)
252                 return -ENOMEM;
253         if (snd_seq_pool_init(newpool) < 0) {
254                 snd_seq_pool_delete(&newpool);
255                 return -ENOMEM;
256         }
257 
258         spin_lock_irqsave(&f->lock, flags);
259         /* remember old pool */
260         oldpool = f->pool;
261         oldhead = f->head;
262         /* exchange pools */
263         f->pool = newpool;
264         f->head = NULL;
265         f->tail = NULL;
266         f->cells = 0;
267         /* NOTE: overflow flag is not cleared */
268         spin_unlock_irqrestore(&f->lock, flags);
269 
270         /* close the old pool and wait until all users are gone */
271         snd_seq_pool_mark_closing(oldpool);
272         snd_use_lock_sync(&f->use_lock);
273 
274         /* release cells in old pool */
275         for (cell = oldhead; cell; cell = next) {
276                 next = cell->next;
277                 snd_seq_cell_free(cell);
278         }
279         snd_seq_pool_delete(&oldpool);
280 
281         return 0;
282 }
283 

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