After commit 
19fb1457990b6b7e15586ec7331541a184233acc the callers in
videobuf-core.c that already hold the lock must call
__videobuf_read_start() instead of videobuf_read_start().
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
        if (q->streaming)
                goto done;
        if (!q->reading) {
-               retval = videobuf_read_start(q);
+               retval = __videobuf_read_start(q);
                if (retval < 0)
                        goto done;
        }
                                         struct videobuf_buffer, stream);
        } else {
                if (!q->reading)
-                       videobuf_read_start(q);
+                       __videobuf_read_start(q);
                if (!q->reading) {
                        rc = POLLERR;
                } else if (NULL == q->read_buf) {