V4L/DVB (6276): V4L: videobuf-core.c lock before streaming check

The reading/streaming fields are used for mutual exclusion of the queue and
should be protected by the queue lock.

Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
http://thread.gmane.org/gmane.comp.video.video4linux/34978/focus=34981
Reviewed-by: Ricardo Cerqueira <v4l@cerqueira.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index a27e114cacef..ca67f80184bd 100644
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -289,16 +289,18 @@ int videobuf_reqbufs(struct videobuf_queue *q,
                 return -EINVAL;
         }
 
+        mutex_lock(&q->lock);
         if (q->streaming) {
                 dprintk(1,"reqbufs: streaming already exists\n");
-                return -EBUSY;
+                retval = -EBUSY;
+                goto done;
         }
         if (!list_empty(&q->stream)) {
                 dprintk(1,"reqbufs: stream running\n");
-                return -EBUSY;
+                retval = -EBUSY;
+                goto done;
         }
 
-        mutex_lock(&q->lock);
         count = req->count;
         if (count > VIDEO_MAX_FRAME)
                 count = VIDEO_MAX_FRAME;