linux-kernel - Re: [PATCH] dma-buf: Make mmap callback actually optional

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Message-ID: <20190401071346.GR2665@phenom.ffwll.local>
Date:   Mon, 1 Apr 2019 09:13:46 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     "Andrew F. Davis" <afd@...com>
Cc:     Sumit Semwal <sumit.semwal@...aro.org>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] dma-buf: Make mmap callback actually optional

On Fri, Mar 29, 2019 at 11:52:01AM -0500, Andrew F. Davis wrote:
> The docs state the callback is optional but it is not, make it optional.
> 
> Signed-off-by: Andrew F. Davis <afd@...com>

There's a bunch of dummy mmap implementations we could remove with this,
would be nice to follow up.

Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>

> ---
>  drivers/dma-buf/dma-buf.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 7c858020d14b..4d4ae9fe9ac8 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -90,6 +90,10 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
>  
>  	dmabuf = file->private_data;
>  
> +	/* check if buffer supports mmap */
> +	if (!dmabuf->ops->mmap)
> +		return -EINVAL;
> +
>  	/* check for overflowing the buffer's size */
>  	if (vma->vm_pgoff + vma_pages(vma) >
>  	    dmabuf->size >> PAGE_SHIFT)
> @@ -404,8 +408,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>  			  || !exp_info->ops
>  			  || !exp_info->ops->map_dma_buf
>  			  || !exp_info->ops->unmap_dma_buf
> -			  || !exp_info->ops->release
> -			  || !exp_info->ops->mmap)) {
> +			  || !exp_info->ops->release)) {
>  		return ERR_PTR(-EINVAL);
>  	}
>  
> @@ -906,6 +909,10 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
>  	if (WARN_ON(!dmabuf || !vma))
>  		return -EINVAL;
>  
> +	/* check if buffer supports mmap */
> +	if (!dmabuf->ops->mmap)
> +		return -EINVAL;
> +
>  	/* check for offset overflow */
>  	if (pgoff + vma_pages(vma) < pgoff)
>  		return -EOVERFLOW;
> -- 
> 2.21.0
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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