[libcamera-devel] [PATCH v3 10/12] android: camera_device: Fix variables access without protection

[Laurent Pinchart]

Hi Hiro,

Thank you for the patch.

On Wed, Dec 01, 2021 at 12:55:58AM +0900, Hirokazu Honda wrote:
> This fixes the code accessing descriptors and
> Camera3RequestDescriptor::pendingStreamsToProcess_ without holding
> descriptorsMutex_ and Camera3RequestDescriptor::streamProcessMutex_
> in CameraDevice.
> 
> Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> ---
>  src/android/camera_device.cpp | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> index d74307a2..e513cd84 100644
> --- a/src/android/camera_device.cpp
> +++ b/src/android/camera_device.cpp
> @@ -421,7 +421,11 @@ void CameraDevice::stop()
>  	worker_.stop();
>  	camera_->stop();
>  
> -	descriptors_ = {};
> +	{
> +		MutexLocker descriptorsLock(descriptorsMutex_);
> +		descriptors_ = {};
> +	}
> +
>  	streams_.clear();
>  
>  	state_ = State::Stopped;
> @@ -918,6 +922,8 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
>  		 */
>  		FrameBuffer *frameBuffer = nullptr;
>  		int acquireFence = -1;
> +
> +		MutexLocker lock(descriptor->streamsProcessMutex_);

Blank line here ?

We could lower the amount of code covered by the lock, but that wouldn't
help as there can be lock contention here. I just hope locking and
unlocking an std::mutex that isn't contended is a fast operation.

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

>  		switch (cameraStream->type()) {
>  		case CameraStream::Type::Mapped:
>  			/*

-- 
Regards,

Laurent Pinchart