[PATCH v5 3/3] libcamera: software_isp: Clean up pending requests on stop

[Laurent Pinchart]

Hi Milan,

Thank you for the patch.

On Mon, Oct 21, 2024 at 03:37:18PM +0200, Milan Zamazal wrote:
> PipelineHandler::stop() calls stopDevice() method to perform pipeline
> specific cleanup and then completes waiting requests.  If any queued
> requests remain, an assertion error is raised.
> 
> Software ISP stores request buffers in
> SimpleCameraData::conversionQueue_ and queues them as V4L2 signals
> bufferReady.  stopDevice() cleanup forgets to clean up the buffers and
> their requests from conversionQueue_, possibly resulting in the
> assertion error.  This patch fixes the omission.
> 
> The problem wasn't very visible when
> SimplePipelineHandler::kNumInternalBuffers (the number of buffers
> allocated in V4L2) was equal to the number of buffers exported from
> software ISP.  But when the number of the exported buffers was increased
> by one in commit abe2ec64f9e4e97bbdfe3a50372611bd7b5315c2, the assertion
> error started pop up in some environments.  Increasing the number of the
> buffers much more, e.g. to 9, makes the problem very reproducible.
> 
> Each pipeline uses its own mechanism to track the requests to clean up
> and it can't be excluded that similar omissions are present in other
> places.  But there is no obvious way to make a common cleanup for all
> the pipelines (except for doing it instead of raising the assertion
> error, which is probably undesirable, in order not to hide incomplete
> pipeline specific cleanups).
> 
> Bug: https://bugs.libcamera.org/show_bug.cgi?id=234
> Signed-off-by: Milan Zamazal <mzamazal at redhat.com>
> ---
>  src/libcamera/pipeline/simple/simple.cpp | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
> index f3a6b1635..6b1121c34 100644
> --- a/src/libcamera/pipeline/simple/simple.cpp
> +++ b/src/libcamera/pipeline/simple/simple.cpp
> @@ -288,6 +288,7 @@ public:
>  	};
>  	std::queue<RequestOutputs> conversionQueue_;
>  	bool useConversion_;
> +	void clearIncompleteRequests();

Member functions go before member variables. Functions covered by the
same access specifier (public, protected or private) should also be
ordered the same way in the class definition and in the rest of the
file.

With that fixed,

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

>  
>  	std::unique_ptr<Converter> converter_;
>  	std::unique_ptr<SoftwareIsp> swIsp_;
> @@ -897,6 +898,14 @@ void SimpleCameraData::conversionOutputDone(FrameBuffer *buffer)
>  		pipe->completeRequest(request);
>  }
>  
> +void SimpleCameraData::clearIncompleteRequests()
> +{
> +	while (!conversionQueue_.empty()) {
> +		pipe()->cancelRequest(conversionQueue_.front().request);
> +		conversionQueue_.pop();
> +	}
> +}
> +
>  void SimpleCameraData::ispStatsReady(uint32_t frame, uint32_t bufferId)
>  {
>  	swIsp_->processStats(frame, bufferId,
> @@ -1406,6 +1415,7 @@ void SimplePipelineHandler::stopDevice(Camera *camera)
>  
>  	video->bufferReady.disconnect(data, &SimpleCameraData::bufferReady);
>  
> +	data->clearIncompleteRequests();
>  	data->conversionBuffers_.clear();
>  
>  	releasePipeline(data);

-- 
Regards,

Laurent Pinchart