From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sylwester Nawrocki <snjw23@gmail.com>
Subject: Re: [PATCH 1/3] dma-buf: add vmap interface
Date: Tue, 10 Apr 2012 22:48:17 +0200
Message-ID: <4F849C91.6090504@gmail.com>
References: <1334052691-5145-1-git-send-email-t.stanislaws@samsung.com> <1334052691-5145-2-git-send-email-t.stanislaws@samsung.com>
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To: Tomasz Stanislawski <t.stanislaws@samsung.com>
Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, airlied@redhat.com, m.szyprowski@samsung.com, kyungmin.park@samsung.com, laurent.pinchart@ideasonboard.com, sumit.semwal@ti.com, daeinki@gmail.com, daniel.vetter@ffwll.ch, robdclark@gmail.com, pawel@osciak.com, linaro-mm-sig@lists.linaro.org, subashrp@gmail.com, mchehab@redhat.com
List-Id: dri-devel@lists.freedesktop.org

Hi,

On 04/10/2012 12:11 PM, Tomasz Stanislawski wrote:
> From: Dave Airlie<airlied@redhat.com>
>
> Add vmap to dmabuf interface.
>
> Signed-off-by: Dave Airlie<airlied@redhat.com>
> ---
>   drivers/base/dma-buf.c  |   29 +++++++++++++++++++++++++++++
>   include/linux/dma-buf.h |   16 ++++++++++++++++
>   2 files changed, 45 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index 07cbbc6..3068258 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -406,3 +406,32 @@ void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
>   		dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
>   }
>   EXPORT_SYMBOL_GPL(dma_buf_kunmap);
> +
> +/**
> + * dma_buf_vmap - Create virtual mapping for the buffer object into kernel address space. The same restrictions as for vmap and friends apply.
> + * @dma_buf:	[in]	buffer to vmap
> + *
> + * This call may fail due to lack of virtual mapping address space.
> + */
> +void *dma_buf_vmap(struct dma_buf *dmabuf)
> +{
> +	WARN_ON(!dmabuf);

How about replacing this with:

	if (WARN_ON(!dmabuf))
		return NULL;

to avoid null pointer dereference right below ?

> +	if (dmabuf->ops->vmap)
> +		return dmabuf->ops->vmap(dmabuf);
> +	return NULL;
> +}
> +EXPORT_SYMBOL(dma_buf_vmap);
> +
> +/**
> + * dma_buf_vunmap - Unmap a page obtained by dma_buf_vmap.
> + * @dma_buf:	[in]	buffer to vmap
> + */
> +void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
> +{
> +	WARN_ON(!dmabuf);

and here
	if (WARN_ON(!dmabuf))
		return;
?
> +	if (dmabuf->ops->vunmap)
> +		dmabuf->ops->vunmap(dmabuf, vaddr);
> +}
> +EXPORT_SYMBOL(dma_buf_vunmap);

--

Regards,
Sylwester