From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from galahad.ideasonboard.com ([185.26.127.97]:49785 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752353AbcLOWFo (ORCPT ); Thu, 15 Dec 2016 17:05:44 -0500 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org, pawel@osciak.com, m.szyprowski@samsung.com, kyungmin.park@samsung.com, hverkuil@xs4all.nl, sumit.semwal@linaro.org, robdclark@gmail.com, daniel.vetter@ffwll.ch, labbott@redhat.com Subject: Re: [RFC RESEND 11/11] vb2: dma-contig: Add WARN_ON_ONCE() to check for potential bugs Date: Thu, 15 Dec 2016 23:57:54 +0200 Message-ID: <1547868.pze7WEjWy0@avalon> In-Reply-To: <1441972234-8643-12-git-send-email-sakari.ailus@linux.intel.com> References: <1441972234-8643-1-git-send-email-sakari.ailus@linux.intel.com> <1441972234-8643-12-git-send-email-sakari.ailus@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, Thank you for the patch. On Friday 11 Sep 2015 14:50:34 Sakari Ailus wrote: > The scatterlist should always be present when the cache would need to be > flushed. Each buffer type has its own means to provide that. Add > WARN_ON_ONCE() to check the scatterist exists. Do you think such a check is really needed ? Have you run into this before ? > Signed-off-by: Sakari Ailus > --- > drivers/media/v4l2-core/videobuf2-dma-contig.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c > b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 65ee122..58c35c5 > 100644 > --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c > +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c > @@ -145,6 +145,9 @@ static void vb2_dc_prepare(void *buf_priv) > !dma_get_attr(DMA_ATTR_NON_CONSISTENT, buf->attrs)) > return; > > + if (WARN_ON_ONCE(!sgt)) > + return; > + > dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); > } > > @@ -161,6 +164,9 @@ static void vb2_dc_finish(void *buf_priv) > !dma_get_attr(DMA_ATTR_NON_CONSISTENT, buf->attrs)) > return; > > + if (WARN_ON_ONCE(!sgt)) > + return; > + > dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); > } -- Regards, Laurent Pinchart