3.16-stable review patch. If anyone has any objections, please let me know.
------------------ From: Laurent Pinchart <[email protected]> commit bd994ddb2a12a3ff48cd549ec82cdceaea9614df upstream. videobuf2 stores the driver streaming state internally in the queue in the start_streaming_called variable. The state is set right after the driver start_stream operation returns, and checked in the vb2_buffer_done() function, typically called from the frame completion interrupt handler. A race condition exists if the hardware finishes processing the first frame before the start_stream operation returns. Fix this by setting start_streaming_called to 1 before calling the start_stream operation, and resetting it to 0 if the operation fails. Signed-off-by: Laurent Pinchart <[email protected]> Reviewed-by: Hans Verkuil <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/media/v4l2-core/videobuf2-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -1750,12 +1750,14 @@ static int vb2_start_streaming(struct vb __enqueue_in_driver(vb); /* Tell the driver to start streaming */ + q->start_streaming_called = 1; ret = call_qop(q, start_streaming, q, atomic_read(&q->owned_by_drv_count)); - q->start_streaming_called = ret == 0; if (!ret) return 0; + q->start_streaming_called = 0; + dprintk(1, "driver refused to start streaming\n"); if (WARN_ON(atomic_read(&q->owned_by_drv_count))) { unsigned i; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
