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https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
[ALSA] Fix races in PCM OSS emulation
Fixed the race among multiple threads accessing the OSS PCM instance concurrently by simply introducing a mutex for protecting a setup of the PCM. Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Jaroslav Kysela <perex@suse.cz>
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@ -56,6 +56,7 @@ struct snd_pcm_oss_runtime {
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size_t mmap_bytes;
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char *buffer; /* vmallocated period */
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size_t buffer_used; /* used length from period buffer */
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struct mutex params_lock;
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#ifdef CONFIG_SND_PCM_OSS_PLUGINS
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struct snd_pcm_plugin *plugin_first;
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struct snd_pcm_plugin *plugin_last;
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@ -810,6 +810,8 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream)
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struct snd_mask sformat_mask;
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struct snd_mask mask;
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if (mutex_lock_interruptible(&runtime->oss.params_lock))
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return -EINTR;
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sw_params = kmalloc(sizeof(*sw_params), GFP_KERNEL);
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params = kmalloc(sizeof(*params), GFP_KERNEL);
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sparams = kmalloc(sizeof(*sparams), GFP_KERNEL);
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@ -1020,6 +1022,7 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream)
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kfree(sw_params);
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kfree(params);
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kfree(sparams);
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mutex_unlock(&runtime->oss.params_lock);
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return err;
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}
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@ -1307,14 +1310,17 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha
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if ((tmp = snd_pcm_oss_make_ready(substream)) < 0)
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return tmp;
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mutex_lock(&runtime->oss.params_lock);
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while (bytes > 0) {
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if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) {
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tmp = bytes;
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if (tmp + runtime->oss.buffer_used > runtime->oss.period_bytes)
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tmp = runtime->oss.period_bytes - runtime->oss.buffer_used;
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if (tmp > 0) {
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if (copy_from_user(runtime->oss.buffer + runtime->oss.buffer_used, buf, tmp))
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : -EFAULT;
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if (copy_from_user(runtime->oss.buffer + runtime->oss.buffer_used, buf, tmp)) {
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tmp = -EFAULT;
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goto err;
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}
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}
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runtime->oss.buffer_used += tmp;
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buf += tmp;
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@ -1325,22 +1331,24 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha
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tmp = snd_pcm_oss_write2(substream, runtime->oss.buffer + runtime->oss.period_ptr,
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runtime->oss.buffer_used - runtime->oss.period_ptr, 1);
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if (tmp <= 0)
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
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goto err;
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runtime->oss.bytes += tmp;
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runtime->oss.period_ptr += tmp;
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runtime->oss.period_ptr %= runtime->oss.period_bytes;
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if (runtime->oss.period_ptr == 0 ||
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runtime->oss.period_ptr == runtime->oss.buffer_used)
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runtime->oss.buffer_used = 0;
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else if ((substream->f_flags & O_NONBLOCK) != 0)
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return xfer > 0 ? xfer : -EAGAIN;
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else if ((substream->f_flags & O_NONBLOCK) != 0) {
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tmp = -EAGAIN;
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goto err;
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}
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}
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} else {
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tmp = snd_pcm_oss_write2(substream,
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(const char __force *)buf,
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runtime->oss.period_bytes, 0);
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if (tmp <= 0)
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
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goto err;
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runtime->oss.bytes += tmp;
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buf += tmp;
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bytes -= tmp;
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@ -1350,7 +1358,12 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha
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break;
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}
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}
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mutex_unlock(&runtime->oss.params_lock);
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return xfer;
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err:
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mutex_unlock(&runtime->oss.params_lock);
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
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}
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static ssize_t snd_pcm_oss_read2(struct snd_pcm_substream *substream, char *buf, size_t bytes, int in_kernel)
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@ -1397,12 +1410,13 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
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if ((tmp = snd_pcm_oss_make_ready(substream)) < 0)
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return tmp;
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mutex_lock(&runtime->oss.params_lock);
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while (bytes > 0) {
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if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) {
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if (runtime->oss.buffer_used == 0) {
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tmp = snd_pcm_oss_read2(substream, runtime->oss.buffer, runtime->oss.period_bytes, 1);
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if (tmp <= 0)
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
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goto err;
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runtime->oss.bytes += tmp;
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runtime->oss.period_ptr = tmp;
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runtime->oss.buffer_used = tmp;
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@ -1410,8 +1424,10 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
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tmp = bytes;
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if ((size_t) tmp > runtime->oss.buffer_used)
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tmp = runtime->oss.buffer_used;
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if (copy_to_user(buf, runtime->oss.buffer + (runtime->oss.period_ptr - runtime->oss.buffer_used), tmp))
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : -EFAULT;
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if (copy_to_user(buf, runtime->oss.buffer + (runtime->oss.period_ptr - runtime->oss.buffer_used), tmp)) {
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tmp = -EFAULT;
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goto err;
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}
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buf += tmp;
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bytes -= tmp;
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xfer += tmp;
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@ -1420,14 +1436,19 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
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tmp = snd_pcm_oss_read2(substream, (char __force *)buf,
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runtime->oss.period_bytes, 0);
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if (tmp <= 0)
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
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goto err;
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runtime->oss.bytes += tmp;
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buf += tmp;
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bytes -= tmp;
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xfer += tmp;
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}
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}
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mutex_unlock(&runtime->oss.params_lock);
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return xfer;
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err:
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mutex_unlock(&runtime->oss.params_lock);
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return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
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}
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static int snd_pcm_oss_reset(struct snd_pcm_oss_file *pcm_oss_file)
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@ -1528,6 +1549,7 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
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return err;
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format = snd_pcm_oss_format_from(runtime->oss.format);
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width = snd_pcm_format_physical_width(format);
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mutex_lock(&runtime->oss.params_lock);
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if (runtime->oss.buffer_used > 0) {
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#ifdef OSS_DEBUG
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printk("sync: buffer_used\n");
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@ -1537,8 +1559,10 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
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runtime->oss.buffer + runtime->oss.buffer_used,
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size);
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err = snd_pcm_oss_sync1(substream, runtime->oss.period_bytes);
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if (err < 0)
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if (err < 0) {
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mutex_unlock(&runtime->oss.params_lock);
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return err;
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}
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} else if (runtime->oss.period_ptr > 0) {
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#ifdef OSS_DEBUG
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printk("sync: period_ptr\n");
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@ -1548,8 +1572,10 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
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runtime->oss.buffer,
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size * 8 / width);
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err = snd_pcm_oss_sync1(substream, size);
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if (err < 0)
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if (err < 0) {
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mutex_unlock(&runtime->oss.params_lock);
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return err;
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}
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}
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/*
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* The ALSA's period might be a bit large than OSS one.
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@ -1579,6 +1605,7 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
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snd_pcm_lib_writev(substream, buffers, size);
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}
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}
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mutex_unlock(&runtime->oss.params_lock);
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/*
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* finish sync: drain the buffer
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*/
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@ -2172,6 +2199,7 @@ static void snd_pcm_oss_init_substream(struct snd_pcm_substream *substream,
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runtime->oss.params = 1;
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runtime->oss.trigger = 1;
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runtime->oss.rate = 8000;
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mutex_init(&runtime->oss.params_lock);
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switch (SNDRV_MINOR_OSS_DEVICE(minor)) {
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case SNDRV_MINOR_OSS_PCM_8:
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runtime->oss.format = AFMT_U8;
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