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Date: Sun, 22 Apr 2018 15:53:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.9 63/95] ALSA: pcm: Fix mutex unbalance in OSS emulation ioctls
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Takashi Iwai <tiwai@...e.de>
commit f6d297df4dd47ef949540e4a201230d0c5308325 upstream.
The previous fix 40cab6e88cb0 ("ALSA: pcm: Return -EBUSY for OSS
ioctls changing busy streams") introduced some mutex unbalance; the
check of runtime->oss.rw_ref was inserted in a wrong place after the
mutex lock.
This patch fixes the inconsistency by rewriting with the helper
functions to lock/unlock parameters with the stream check.
Fixes: 40cab6e88cb0 ("ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams")
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
sound/core/oss/pcm_oss.c | 67 +++++++++++++++++++++++++++++------------------
1 file changed, 42 insertions(+), 25 deletions(-)
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -834,6 +834,23 @@ static int choose_rate(struct snd_pcm_su
return snd_pcm_hw_param_near(substream, params, SNDRV_PCM_HW_PARAM_RATE, best_rate, NULL);
}
+/* parameter locking: returns immediately if tried during streaming */
+static int lock_params(struct snd_pcm_runtime *runtime)
+{
+ if (mutex_lock_interruptible(&runtime->oss.params_lock))
+ return -ERESTARTSYS;
+ if (atomic_read(&runtime->oss.rw_ref)) {
+ mutex_unlock(&runtime->oss.params_lock);
+ return -EBUSY;
+ }
+ return 0;
+}
+
+static void unlock_params(struct snd_pcm_runtime *runtime)
+{
+ mutex_unlock(&runtime->oss.params_lock);
+}
+
/* call with params_lock held */
static int snd_pcm_oss_change_params_locked(struct snd_pcm_substream *substream)
{
@@ -1773,6 +1790,8 @@ static int snd_pcm_oss_set_rate(struct s
for (idx = 1; idx >= 0; --idx) {
struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
struct snd_pcm_runtime *runtime;
+ int err;
+
if (substream == NULL)
continue;
runtime = substream->runtime;
@@ -1780,15 +1799,14 @@ static int snd_pcm_oss_set_rate(struct s
rate = 1000;
else if (rate > 192000)
rate = 192000;
- if (mutex_lock_interruptible(&runtime->oss.params_lock))
- return -ERESTARTSYS;
- if (atomic_read(&runtime->oss.rw_ref))
- return -EBUSY;
+ err = lock_params(runtime);
+ if (err < 0)
+ return err;
if (runtime->oss.rate != rate) {
runtime->oss.params = 1;
runtime->oss.rate = rate;
}
- mutex_unlock(&runtime->oss.params_lock);
+ unlock_params(runtime);
}
return snd_pcm_oss_get_rate(pcm_oss_file);
}
@@ -1813,18 +1831,19 @@ static int snd_pcm_oss_set_channels(stru
for (idx = 1; idx >= 0; --idx) {
struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
struct snd_pcm_runtime *runtime;
+ int err;
+
if (substream == NULL)
continue;
runtime = substream->runtime;
- if (mutex_lock_interruptible(&runtime->oss.params_lock))
- return -ERESTARTSYS;
- if (atomic_read(&runtime->oss.rw_ref))
- return -EBUSY;
+ err = lock_params(runtime);
+ if (err < 0)
+ return err;
if (runtime->oss.channels != channels) {
runtime->oss.params = 1;
runtime->oss.channels = channels;
}
- mutex_unlock(&runtime->oss.params_lock);
+ unlock_params(runtime);
}
return snd_pcm_oss_get_channels(pcm_oss_file);
}
@@ -1897,6 +1916,7 @@ static int snd_pcm_oss_get_formats(struc
static int snd_pcm_oss_set_format(struct snd_pcm_oss_file *pcm_oss_file, int format)
{
int formats, idx;
+ int err;
if (format != AFMT_QUERY) {
formats = snd_pcm_oss_get_formats(pcm_oss_file);
@@ -1910,15 +1930,14 @@ static int snd_pcm_oss_set_format(struct
if (substream == NULL)
continue;
runtime = substream->runtime;
- if (atomic_read(&runtime->oss.rw_ref))
- return -EBUSY;
- if (mutex_lock_interruptible(&runtime->oss.params_lock))
- return -ERESTARTSYS;
+ err = lock_params(runtime);
+ if (err < 0)
+ return err;
if (runtime->oss.format != format) {
runtime->oss.params = 1;
runtime->oss.format = format;
}
- mutex_unlock(&runtime->oss.params_lock);
+ unlock_params(runtime);
}
}
return snd_pcm_oss_get_format(pcm_oss_file);
@@ -1966,12 +1985,11 @@ static int snd_pcm_oss_set_subdivide(str
if (substream == NULL)
continue;
runtime = substream->runtime;
- if (atomic_read(&runtime->oss.rw_ref))
- return -EBUSY;
- if (mutex_lock_interruptible(&runtime->oss.params_lock))
- return -ERESTARTSYS;
+ err = lock_params(runtime);
+ if (err < 0)
+ return err;
err = snd_pcm_oss_set_subdivide1(substream, subdivide);
- mutex_unlock(&runtime->oss.params_lock);
+ unlock_params(runtime);
if (err < 0)
return err;
}
@@ -2006,12 +2024,11 @@ static int snd_pcm_oss_set_fragment(stru
if (substream == NULL)
continue;
runtime = substream->runtime;
- if (atomic_read(&runtime->oss.rw_ref))
- return -EBUSY;
- if (mutex_lock_interruptible(&runtime->oss.params_lock))
- return -ERESTARTSYS;
+ err = lock_params(runtime);
+ if (err < 0)
+ return err;
err = snd_pcm_oss_set_fragment1(substream, val);
- mutex_unlock(&runtime->oss.params_lock);
+ unlock_params(runtime);
if (err < 0)
return err;
}
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