| Message ID | 1403567669-18539-6-git-send-email-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/24/14 01:54, Laurent Pinchart wrote: > 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 <laurent.pinchart+renesas@ideasonboard.com> Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com> Good catch! This needs a: Cc: stable@vger.kernel.org # for v3.15 and up Regards, Hans > --- > drivers/media/v4l2-core/videobuf2-core.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 7c4489c..1d67e95 100644 > --- 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 vb2_queue *q) > __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-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 7c4489c..1d67e95 100644 --- 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 vb2_queue *q) __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;
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 <laurent.pinchart+renesas@ideasonboard.com> --- drivers/media/v4l2-core/videobuf2-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)