sound/core/seq/seq_fifo.c

   1 /*
   2  *   ALSA sequencer FIFO
   3  *   Copyright (c) 1998 by Frank van de Pol <[email protected]>
   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); /* 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 }