sound/core/seq/seq_fifo.c

   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         snd_seq_fifo_clear(f);
  76
  77         /* wake up clients if any */
  78         if (waitqueue_active(&f->input_sleep))
  79                 wake_up(&f->input_sleep);
  80
  81         /* release resources...*/
  82         /*....................*/
  83
  84         if (f->pool) {
  85                 snd_seq_pool_done(f->pool);
  86                 snd_seq_pool_delete(&f->pool);
  87         }
  88
  89         kfree(f);
  90 }
  91
  92 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
  93
  94 /* clear queue */
  95 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
  96 {
  97         struct snd_seq_event_cell *cell;
  98         unsigned long flags;
  99
 100         /* clear overflow flag */
 101         atomic_set(&f->overflow, 0);
 102
 103         snd_use_lock_sync(&f->use_lock);
 104         spin_lock_irqsave(&f->lock, flags);
 105         /* drain the fifo */
 106         while ((cell = fifo_cell_out(f)) != NULL) {
 107                 snd_seq_cell_free(cell);
 108         }
 109         spin_unlock_irqrestore(&f->lock, flags);
 110 }
 111
 112
 113 /* enqueue event to fifo */
 114 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
 115                           struct snd_seq_event *event)
 116 {
 117         struct snd_seq_event_cell *cell;
 118         unsigned long flags;
 119         int err;
 120
 121         if (snd_BUG_ON(!f))
 122                 return -EINVAL;
 123
 124         snd_use_lock_use(&f->use_lock);
 125         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
 126         if (err < 0) {
 127                 if ((err == -ENOMEM) || (err == -EAGAIN))
 128                         atomic_inc(&f->overflow);
 129                 snd_use_lock_free(&f->use_lock);
 130                 return err;
 131         }
 132
 133         /* append new cells to fifo */
 134         spin_lock_irqsave(&f->lock, flags);
 135         if (f->tail != NULL)
 136                 f->tail->next = cell;
 137         f->tail = cell;
 138         if (f->head == NULL)
 139                 f->head = cell;
 140         cell->next = NULL;
 141         f->cells++;
 142         spin_unlock_irqrestore(&f->lock, flags);
 143
 144         /* wakeup client */
 145         if (waitqueue_active(&f->input_sleep))
 146                 wake_up(&f->input_sleep);
 147
 148         snd_use_lock_free(&f->use_lock);
 149
 150         return 0; /* success */
 151
 152 }
 153
 154 /* dequeue cell from fifo */
 155 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
 156 {
 157         struct snd_seq_event_cell *cell;
 158
 159         if ((cell = f->head) != NULL) {
 160                 f->head = cell->next;
 161
 162                 /* reset tail if this was the last element */
 163                 if (f->tail == cell)
 164                         f->tail = NULL;
 165
 166                 cell->next = NULL;
 167                 f->cells--;
 168         }
 169
 170         return cell;
 171 }
 172
 173 /* dequeue cell from fifo and copy on user space */
 174 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
 175                           struct snd_seq_event_cell **cellp, int nonblock)
 176 {
 177         struct snd_seq_event_cell *cell;
 178         unsigned long flags;
 179         wait_queue_t wait;
 180
 181         if (snd_BUG_ON(!f))
 182                 return -EINVAL;
 183
 184         *cellp = NULL;
 185         init_waitqueue_entry(&wait, current);
 186         spin_lock_irqsave(&f->lock, flags);
 187         while ((cell = fifo_cell_out(f)) == NULL) {
 188                 if (nonblock) {
 189                         /* non-blocking - return immediately */
 190                         spin_unlock_irqrestore(&f->lock, flags);
 191                         return -EAGAIN;
 192                 }
 193                 set_current_state(TASK_INTERRUPTIBLE);
 194                 add_wait_queue(&f->input_sleep, &wait);
 195                 spin_unlock_irq(&f->lock);
 196                 schedule();
 197                 spin_lock_irq(&f->lock);
 198                 remove_wait_queue(&f->input_sleep, &wait);
 199                 if (signal_pending(current)) {
 200                         spin_unlock_irqrestore(&f->lock, flags);
 201                         return -ERESTARTSYS;
 202                 }
 203         }
 204         spin_unlock_irqrestore(&f->lock, flags);
 205         *cellp = cell;
 206
 207         return 0;
 208 }
 209
 210
 211 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 212                                struct snd_seq_event_cell *cell)
 213 {
 214         unsigned long flags;
 215
 216         if (cell) {
 217                 spin_lock_irqsave(&f->lock, flags);
 218                 cell->next = f->head;
 219                 f->head = cell;
 220                 if (!f->tail)
 221                         f->tail = cell;
 222                 f->cells++;
 223                 spin_unlock_irqrestore(&f->lock, flags);
 224         }
 225 }
 226
 227
 228 /* polling; return non-zero if queue is available */
 229 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 230                            poll_table *wait)
 231 {
 232         poll_wait(file, &f->input_sleep, wait);
 233         return (f->cells > 0);
 234 }
 235
 236 /* change the size of pool; all old events are removed */
 237 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 238 {
 239         unsigned long flags;
 240         struct snd_seq_pool *newpool, *oldpool;
 241         struct snd_seq_event_cell *cell, *next, *oldhead;
 242
 243         if (snd_BUG_ON(!f || !f->pool))
 244                 return -EINVAL;
 245
 246         /* allocate new pool */
 247         newpool = snd_seq_pool_new(poolsize);
 248         if (newpool == NULL)
 249                 return -ENOMEM;
 250         if (snd_seq_pool_init(newpool) < 0) {
 251                 snd_seq_pool_delete(&newpool);
 252                 return -ENOMEM;
 253         }
 254
 255         spin_lock_irqsave(&f->lock, flags);
 256         /* remember old pool */
 257         oldpool = f->pool;
 258         oldhead = f->head;
 259         /* exchange pools */
 260         f->pool = newpool;
 261         f->head = NULL;
 262         f->tail = NULL;
 263         f->cells = 0;
 264         /* NOTE: overflow flag is not cleared */
 265         spin_unlock_irqrestore(&f->lock, flags);
 266
 267         /* release cells in old pool */
 268         for (cell = oldhead; cell; cell = next) {
 269                 next = cell->next;
 270                 snd_seq_cell_free(cell);
 271         }
 272         snd_seq_pool_delete(&oldpool);
 273
 274         return 0;
 275 }