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>

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();
 }