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authorHans Verkuil <hverkuil@xs4all.nl>2008-07-26 09:01:24 -0300
committerMauro Carvalho Chehab <mchehab@infradead.org>2008-07-27 11:06:23 -0300
commit1052efe0fc69130d9d6a44bc9ceecd229221d9a1 (patch)
tree7e7f19cbbd3ff023e80eb7da5b68469085bdfe59
parentfeb75f07102a85026d41e2c4e4113c34dd035c30 (diff)
V4L/DVB (8505): saa7134-empress.c: fix deadlock
ts_release() locked a mutex that videobuf_stop() also tried to obtain. But ts_release() shouldn't hold that mutex at all. Make empress_users atomic as well to prevent possible race condition. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
-rw-r--r--drivers/media/video/saa7134/saa7134-empress.c12
-rw-r--r--drivers/media/video/saa7134/saa7134.h2
2 files changed, 5 insertions, 9 deletions
diff --git a/drivers/media/video/saa7134/saa7134-empress.c b/drivers/media/video/saa7134/saa7134-empress.c
index 8b3f9516778..2ecfbd1b41f 100644
--- a/drivers/media/video/saa7134/saa7134-empress.c
+++ b/drivers/media/video/saa7134/saa7134-empress.c
@@ -89,14 +89,14 @@ static int ts_open(struct inode *inode, struct file *file)
err = -EBUSY;
if (!mutex_trylock(&dev->empress_tsq.vb_lock))
goto done;
- if (dev->empress_users)
+ if (atomic_read(&dev->empress_users))
goto done_up;
/* Unmute audio */
saa_writeb(SAA7134_AUDIO_MUTE_CTRL,
saa_readb(SAA7134_AUDIO_MUTE_CTRL) & ~(1 << 6));
- dev->empress_users++;
+ atomic_inc(&dev->empress_users);
file->private_data = dev;
err = 0;
@@ -110,8 +110,6 @@ static int ts_release(struct inode *inode, struct file *file)
{
struct saa7134_dev *dev = file->private_data;
- mutex_lock(&dev->empress_tsq.vb_lock);
-
videobuf_stop(&dev->empress_tsq);
videobuf_mmap_free(&dev->empress_tsq);
@@ -122,9 +120,7 @@ static int ts_release(struct inode *inode, struct file *file)
saa_writeb(SAA7134_AUDIO_MUTE_CTRL,
saa_readb(SAA7134_AUDIO_MUTE_CTRL) | (1 << 6));
- dev->empress_users--;
-
- mutex_unlock(&dev->empress_tsq.vb_lock);
+ atomic_dec(&dev->empress_users);
return 0;
}
@@ -447,7 +443,7 @@ static void empress_signal_update(struct work_struct *work)
ts_reset_encoder(dev);
} else {
dprintk("video signal acquired\n");
- if (dev->empress_users)
+ if (atomic_read(&dev->empress_users))
ts_init_encoder(dev);
}
}
diff --git a/drivers/media/video/saa7134/saa7134.h b/drivers/media/video/saa7134/saa7134.h
index ade4e19799e..ed20dd56379 100644
--- a/drivers/media/video/saa7134/saa7134.h
+++ b/drivers/media/video/saa7134/saa7134.h
@@ -561,7 +561,7 @@ struct saa7134_dev {
/* SAA7134_MPEG_EMPRESS only */
struct video_device *empress_dev;
struct videobuf_queue empress_tsq;
- unsigned int empress_users;
+ atomic_t empress_users;
struct work_struct empress_workqueue;
int empress_started;