From: Simon Arlott <simon@xxxxxxxxxxx>
dvb_dvr_read may unlock the dmxdev mutex and return -ENODEV, except this
function is a file op and will never be called with the mutex held.
There's existing mutex_lock and mutex_unlock around the actual read but
it's commented out. These should probably be uncommented but the read
blocks and this could block another non-blocking reader on the mutex
instead.
This change comments out the extra mutex_unlock.
[akpm@xxxxxxxxxxxxxxxxxxxx: cleanups, simplification]
Signed-off-by: Simon Arlott <simon@xxxxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/media/dvb/dvb-core/dmxdev.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff -puN drivers/media/dvb/dvb-core/dmxdev.c~dvb-core-fix-potential-mutex_unlock-without-mutex_lock-in-dvb_dvr_read drivers/media/dvb/dvb-core/dmxdev.c
--- a/drivers/media/dvb/dvb-core/dmxdev.c~dvb-core-fix-potential-mutex_unlock-without-mutex_lock-in-dvb_dvr_read
+++ a/drivers/media/dvb/dvb-core/dmxdev.c
@@ -244,19 +244,13 @@ static ssize_t dvb_dvr_read(struct file
{
struct dvb_device *dvbdev = file->private_data;
struct dmxdev *dmxdev = dvbdev->priv;
- int ret;
- if (dmxdev->exit) {
- mutex_unlock(&dmxdev->mutex);
+ if (dmxdev->exit)
return -ENODEV;
- }
- //mutex_lock(&dmxdev->mutex);
- ret = dvb_dmxdev_buffer_read(&dmxdev->dvr_buffer,
- file->f_flags & O_NONBLOCK,
- buf, count, ppos);
- //mutex_unlock(&dmxdev->mutex);
- return ret;
+ return dvb_dmxdev_buffer_read(&dmxdev->dvr_buffer,
+ file->f_flags & O_NONBLOCK,
+ buf, count, ppos);
}
static int dvb_dvr_set_buffer_size(struct dmxdev *dmxdev,
_
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