V4L/DVB (6601): V4L: videobuf-core locking fixes and comments

- Add comments to functions that require that caller hold q->lock
- Add __videobuf_mmap_free that doesn't hold q->lock for use within videobuf
- Add locking to videobuf_mmap_free
- Fix linux/drivers/media/common/saa7146_video.c which was holding lock around
  videobuf_read_stop
- Add locking to functions that operate on a queue
- Add videobuf_stop to take care of stopping in both the read and stream case

TODO: bttv still has an unsafe call to videobuf_queue_is_busy

Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/media/common/saa7146_video.c b/drivers/media/common/saa7146_video.c
index f245a3b2ef47..7cc4213ba56b 100644
--- a/drivers/media/common/saa7146_video.c
+++ b/drivers/media/common/saa7146_video.c
@@ -1440,10 +1440,7 @@ static void video_close(struct saa7146_dev *dev, struct file *file)
                 err = saa7146_stop_preview(fh);
         }
 
-        // release all capture buffers
-        mutex_lock(&q->lock);
-        videobuf_read_stop(q);
-        mutex_unlock(&q->lock);
+        videobuf_stop(q);
 
         /* hmm, why is this function declared void? */
         /* return err */