libcamera: v4l2_videodevice: Signal buffer completion at streamoff time

When stopping the stream buffers have been queued, in which case their
completion is never be notified to the user. This can lead to memory
leaks. Fix it by notifying completion of all queued buffers with the
status set to error.

As a result the base PipelineHandler implementation can be simplified,
as all requests complete as the result of stopping the stream. The
stop() method that manually completes all queued requests isn't needed
anymore.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

10 files changed, 34 insertions, 40 deletions

diff --git a/include/libcamera/request.h b/include/libcamera/request.h
index f69b4e7a..9edf1ced 100644
--- a/include/libcamera/request.h
+++ b/include/libcamera/request.h
@@ -51,7 +51,7 @@ private:
 	friend class PipelineHandler;
 
 	int prepare();
-	void complete(Status status);
+	void complete();
 
 	bool completeBuffer(Buffer *buffer);
 
@@ -62,6 +62,7 @@ private:
 
 	const uint64_t cookie_;
 	Status status_;
+	bool cancelled_;
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
index f836d5d1..1fdef9ce 100644
--- a/src/libcamera/include/pipeline_handler.h
+++ b/src/libcamera/include/pipeline_handler.h
@@ -74,7 +74,7 @@ public:
 				const std::set<Stream *> &streams) = 0;
 
 	virtual int start(Camera *camera) = 0;
-	virtual void stop(Camera *camera);
+	virtual void stop(Camera *camera) = 0;
 
 	virtual int queueRequest(Camera *camera, Request *request);
 
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 5a14edb6..7a54c1fd 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -711,8 +711,6 @@ void PipelineHandlerIPU3::stop(Camera *camera)
 	if (ret)
 		LOG(IPU3, Warning) << "Failed to stop camera "
 				   << camera->name();
-
-	PipelineHandler::stop(camera);
 }
 
 int PipelineHandlerIPU3::queueRequest(Camera *camera, Request *request)
diff --git a/src/libcamera/pipeline/rkisp1/rkisp1.cpp b/src/libcamera/pipeline/rkisp1/rkisp1.cpp
index 38323643..cc33a2cb 100644
--- a/src/libcamera/pipeline/rkisp1/rkisp1.cpp
+++ b/src/libcamera/pipeline/rkisp1/rkisp1.cpp
@@ -354,8 +354,6 @@ void PipelineHandlerRkISP1::stop(Camera *camera)
 		LOG(RkISP1, Warning)
 			<< "Failed to stop camera " << camera->name();
 
-	PipelineHandler::stop(camera);
-
 	activeCamera_ = nullptr;
 }
 
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index 387d71ef..b299c5da 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -220,7 +220,6 @@ void PipelineHandlerUVC::stop(Camera *camera)
 {
 	UVCCameraData *data = cameraData(camera);
 	data->video_->streamOff();
-	PipelineHandler::stop(camera);
 }
 
 int PipelineHandlerUVC::processControls(UVCCameraData *data, Request *request)
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index ff2529c9..7d96c364 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -222,7 +222,6 @@ void PipelineHandlerVimc::stop(Camera *camera)
 {
 	VimcCameraData *data = cameraData(camera);
 	data->video_->streamOff();
-	PipelineHandler::stop(camera);
 }
 
 int PipelineHandlerVimc::processControls(VimcCameraData *data, Request *request)
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index c6092002..83938a71 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -328,31 +328,7 @@ const ControlInfoMap &PipelineHandler::controls(Camera *camera)
  *
  * This method stops capturing and processing requests immediately. All pending
  * requests are cancelled and complete immediately in an error state.
- *
- * Pipeline handlers shall override this method to stop the pipeline, ensure
- * that all pending request completion signaled through completeRequest() have
- * returned, and call the base implementation of the stop() method as the last
- * step of their implementation. The base implementation cancels all requests
- * queued but not yet complete.
  */
-void PipelineHandler::stop(Camera *camera)
-{
-	CameraData *data = cameraData(camera);
-
-	while (!data->queuedRequests_.empty()) {
-		Request *request = data->queuedRequests_.front();
-		data->queuedRequests_.pop_front();
-
-		while (!request->pending_.empty()) {
-			Buffer *buffer = *request->pending_.begin();
-			buffer->cancel();
-			completeBuffer(camera, request, buffer);
-		}
-
-		request->complete(Request::RequestCancelled);
-		camera->requestComplete(request);
-	}
-}
 
 /**
  * \fn PipelineHandler::queueRequest()
@@ -420,15 +396,16 @@ bool PipelineHandler::completeBuffer(Camera *camera, Request *request,
  */
 void PipelineHandler::completeRequest(Camera *camera, Request *request)
 {
-	request->complete(Request::RequestComplete);
+	request->complete();
 
 	CameraData *data = cameraData(camera);
 
 	while (!data->queuedRequests_.empty()) {
 		request = data->queuedRequests_.front();
-		if (request->hasPendingBuffers())
+		if (request->status() == Request::RequestPending)
 			break;
 
+		ASSERT(!request->hasPendingBuffers());
 		data->queuedRequests_.pop_front();
 		camera->requestComplete(request);
 	}
diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
index 45e7133f..19131472 100644
--- a/src/libcamera/request.cpp
+++ b/src/libcamera/request.cpp
@@ -56,7 +56,7 @@ LOG_DEFINE_CATEGORY(Request)
  */
 Request::Request(Camera *camera, uint64_t cookie)
 	: camera_(camera), controls_(camera), cookie_(cookie),
-	  status_(RequestPending)
+	  status_(RequestPending), cancelled_(false)
 {
 }
 
@@ -199,14 +199,15 @@ int Request::prepare()
 
 /**
  * \brief Complete a queued request
- * \param[in] status The request completion status
  *
- * Mark the request as complete by updating its status to \a status.
+ * Mark the request as complete by updating its status to RequestComplete,
+ * unless buffers have been cancelled in which case the status is set to
+ * RequestCancelled.
  */
-void Request::complete(Status status)
+void Request::complete()
 {
 	ASSERT(!hasPendingBuffers());
-	status_ = status;
+	status_ = cancelled_ ? RequestCancelled : RequestComplete;
 }
 
 /**
@@ -229,6 +230,9 @@ bool Request::completeBuffer(Buffer *buffer)
 
 	buffer->setRequest(nullptr);
 
+	if (buffer->status() == Buffer::BufferCancelled)
+		cancelled_ = true;
+
 	return !hasPendingBuffers();
 }
 
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 86e299c0..c43d7cc5 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -1089,7 +1089,9 @@ int V4L2VideoDevice::streamOn()
  * \brief Stop the video stream
  *
  * Buffers that are still queued when the video stream is stopped are
- * implicitly dequeued, but no bufferReady signal is emitted for them.
+ * immediately dequeued with their status set to Buffer::BufferError,
+ * and the bufferReady signal is emitted for them. The order in which those
+ * buffers are dequeued is not specified.
  *
  * \return 0 on success or a negative error code otherwise
  */
@@ -1104,6 +1106,16 @@ int V4L2VideoDevice::streamOff()
 		return ret;
 	}
 
+	/* Send back all queued buffers. */
+	for (auto it : queuedBuffers_) {
+		unsigned int index = it.first;
+		Buffer *buffer = it.second;
+
+		buffer->index_ = index;
+		buffer->cancel();
+		bufferReady.emit(buffer);
+	}
+
 	queuedBuffers_.clear();
 	fdEvent_->setEnabled(false);
 
diff --git a/test/v4l2_videodevice/buffer_sharing.cpp b/test/v4l2_videodevice/buffer_sharing.cpp
index da052f34..12ec88f2 100644
--- a/test/v4l2_videodevice/buffer_sharing.cpp
+++ b/test/v4l2_videodevice/buffer_sharing.cpp
@@ -95,6 +95,9 @@ protected:
 		std::cout << "Received capture buffer: " << buffer->index()
 			  << " sequence " << buffer->sequence() << std::endl;
 
+		if (buffer->status() != Buffer::BufferSuccess)
+			return;
+
 		output_->queueBuffer(buffer);
 		framesCaptured_++;
 	}
@@ -104,6 +107,9 @@ protected:
 		std::cout << "Received output buffer: " << buffer->index()
 			  << " sequence " << buffer->sequence() << std::endl;
 
+		if (buffer->status() != Buffer::BufferSuccess)
+			return;
+
 		capture_->queueBuffer(buffer);
 		framesOutput_++;
 	}