From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kernel.org ([198.145.29.136]:55022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941266AbcLMSEJ (ORCPT ); Tue, 13 Dec 2016 13:04:09 -0500 From: Kieran Bingham To: laurent.pinchart@ideasonboard.com Cc: linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org, Kieran Bingham Subject: [PATCHv3 RFC 4/4] media: Catch null pipes on pipeline stop Date: Tue, 13 Dec 2016 17:59:44 +0000 Message-Id: <1481651984-7687-5-git-send-email-kieran.bingham+renesas@ideasonboard.com> In-Reply-To: <1481651984-7687-1-git-send-email-kieran.bingham+renesas@ideasonboard.com> References: <1481651984-7687-1-git-send-email-kieran.bingham+renesas@ideasonboard.com> Sender: linux-media-owner@vger.kernel.org List-ID: media_entity_pipeline_stop() can be called through error paths with a NULL entity pipe object. In this instance, stopping is a no-op, so simply return without any action Signed-off-by: Kieran Bingham --- I've marked this patch as RFC, although if deemed suitable, by all means integrate it as is. When testing suspend/resume operations on VSP1, I encountered a segfault on the WARN_ON(!pipe->streaming_count) line, where 'pipe == NULL'. The simple protection fix is to return early in this instance, as this patch does however: A) Does this early return path warrant a WARN() statement itself, to identify drivers which are incorrectly calling media_entity_pipeline_stop() with an invalid entity, or would this just be noise ... and therefore.. B) I also partly assume this patch could simply get NAK'd with a request to go and dig out the root cause of calling media_entity_pipeline_stop() with an invalid entity. My brief investigation so far here so far shows that it's almost a second order fault - where the first suspend resume cycle completes but leaves the entity in an invalid state having followed an error path - and then on a second suspend/resume - the stop fails with the affected segfault. If statement A) or B) apply here, please drop this patch from the series, and don't consider it a blocking issue for the other 3 patches. Kieran drivers/media/media-entity.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c index c68239e60487..93c9cbf4bf46 100644 --- a/drivers/media/media-entity.c +++ b/drivers/media/media-entity.c @@ -508,6 +508,8 @@ void __media_entity_pipeline_stop(struct media_entity *entity) struct media_entity_graph *graph = &entity->pipe->graph; struct media_pipeline *pipe = entity->pipe; + if (!pipe) + return; WARN_ON(!pipe->streaming_count); media_entity_graph_walk_start(graph, entity); -- 2.7.4