From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:58896 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751197Ab2HOSYS (ORCPT ); Wed, 15 Aug 2012 14:24:18 -0400 From: Laurent Pinchart To: Tomasz Stanislawski Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, airlied@redhat.com, m.szyprowski@samsung.com, kyungmin.park@samsung.com, sumit.semwal@ti.com, daeinki@gmail.com, daniel.vetter@ffwll.ch, robdclark@gmail.com, pawel@osciak.com, linaro-mm-sig@lists.linaro.org, hverkuil@xs4all.nl, remi@remlab.net, subashrp@gmail.com, mchehab@redhat.com, g.liakhovetski@gmx.de, dmitriyz@google.com, s.nawrocki@samsung.com, k.debski@samsung.com Subject: Re: [PATCHv8 06/26] v4l: vb2-dma-contig: remove reference of alloc_ctx from a buffer Date: Wed, 15 Aug 2012 20:24:32 +0200 Message-ID: <2417829.O1YMMu0gWf@avalon> In-Reply-To: <1344958496-9373-7-git-send-email-t.stanislaws@samsung.com> References: <1344958496-9373-1-git-send-email-t.stanislaws@samsung.com> <1344958496-9373-7-git-send-email-t.stanislaws@samsung.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 Tomasz, Thanks for the patch. On Tuesday 14 August 2012 17:34:36 Tomasz Stanislawski wrote: > This patch removes a reference to alloc_ctx from an instance of a DMA > contiguous buffer. It helps to avoid a risk of a dangling pointer if the > context is released while the buffer is still valid. Moreover it removes one > dereference step while accessing a device structure. > > Signed-off-by: Tomasz Stanislawski > Signed-off-by: Kyungmin Park Acked-by: Laurent Pinchart > --- > drivers/media/video/videobuf2-dma-contig.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/drivers/media/video/videobuf2-dma-contig.c > b/drivers/media/video/videobuf2-dma-contig.c index a05784f..20c95da 100644 > --- a/drivers/media/video/videobuf2-dma-contig.c > +++ b/drivers/media/video/videobuf2-dma-contig.c > @@ -23,7 +23,7 @@ struct vb2_dc_conf { > }; > > struct vb2_dc_buf { > - struct vb2_dc_conf *conf; > + struct device *dev; > void *vaddr; > dma_addr_t dma_addr; > unsigned long size; > @@ -37,22 +37,21 @@ static void vb2_dc_put(void *buf_priv); > static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size) > { > struct vb2_dc_conf *conf = alloc_ctx; > + struct device *dev = conf->dev; > struct vb2_dc_buf *buf; > > buf = kzalloc(sizeof *buf, GFP_KERNEL); > if (!buf) > return ERR_PTR(-ENOMEM); > > - buf->vaddr = dma_alloc_coherent(conf->dev, size, &buf->dma_addr, > - GFP_KERNEL); > + buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr, GFP_KERNEL); > if (!buf->vaddr) { > - dev_err(conf->dev, "dma_alloc_coherent of size %ld failed\n", > - size); > + dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size); > kfree(buf); > return ERR_PTR(-ENOMEM); > } > > - buf->conf = conf; > + buf->dev = dev; > buf->size = size; > > buf->handler.refcount = &buf->refcount; > @@ -69,7 +68,7 @@ static void vb2_dc_put(void *buf_priv) > struct vb2_dc_buf *buf = buf_priv; > > if (atomic_dec_and_test(&buf->refcount)) { > - dma_free_coherent(buf->conf->dev, buf->size, buf->vaddr, > + dma_free_coherent(buf->dev, buf->size, buf->vaddr, > buf->dma_addr); > kfree(buf); > } -- Regards, Laurent Pinchart