[libcamera-devel] [PATCH v5 6/8] libcamera: v4l2_videodevice: Do not allow buffer queueing in stopping state

[Laurent Pinchart]

Hi Naush,

Thank you for the patch.

On Fri, Mar 25, 2022 at 09:09:01AM +0000, Naushir Patuck via libcamera-devel wrote:
> If the device is in the process of being stopped (i.e. Stopping state), any
> call to queueBuffer() must fail. This is to ensure the integrity of the buffer
> queue, as it gets cleared at the end of streamOff.
> 
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> ---
>  src/libcamera/v4l2_videodevice.cpp | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index 9cea6a608660..28f336086b49 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -1491,6 +1491,9 @@ int V4L2VideoDevice::releaseBuffers()
>   * The best available V4L2 buffer is picked for \a buffer using the V4L2 buffer
>   * cache.
>   *
> + * Note that queueBuffer() will fail if the device is in the process of being
> + * stopped from a streaming state through streamOff().
> + *
>   * \return 0 on success or a negative error code otherwise
>   */
>  int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
> @@ -1499,6 +1502,11 @@ int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
>  	struct v4l2_buffer buf = {};
>  	int ret;
>  
> +	if (state_ == State::Stopping) {
> +		LOG(V4L2, Error) << "Device is in a stopping state.";
> +		return -ESHUTDOWN;
> +	}
> +
>  	/*
>  	 * Pipeline handlers should not requeue buffers after releasing the
>  	 * buffers on the device. Any occurence of this error should be fixed

-- 
Regards,

Laurent Pinchart