linux-kernel - Re: [PATCH] dma-buf: document fd flags and O

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Message-ID: <20120319154433.GP4917@intel.com>
Date:	Mon, 19 Mar 2012 17:44:33 +0200
From:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:	Daniel Vetter <daniel.vetter@...ll.ch>
Cc:	linaro-mm-sig@...ts.linaro.org,
	LKML <linux-kernel@...r.kernel.org>,
	DRI Development <dri-devel@...ts.freedesktop.org>,
	linux-media@...r.kernel.org
Subject: Re: [PATCH] dma-buf: document fd flags and O_CLOEXEC requirement

On Mon, Mar 19, 2012 at 04:41:55PM +0100, Daniel Vetter wrote:
> Otherwise subsystems will get this wrong and end up with a second
> export ioctl with the flag and O_CLOEXEC support added.
> 
> v2: Fixup the function name and caution exporters to limit the flags
> to only O_CLOEXEC. Noted by Dave Airlie.
> 
> Cc: Dave Airlie <airlied@...il.com>
> Signed-Off-by: Daniel Vetter <daniel.vetter@...ll.ch>
> ---
>  Documentation/dma-buf-sharing.txt |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt
> index 9f3aeef..a6d4c37 100644
> --- a/Documentation/dma-buf-sharing.txt
> +++ b/Documentation/dma-buf-sharing.txt
> @@ -319,6 +319,12 @@ Miscellaneous notes
>  - Any exporters or users of the dma-buf buffer sharing framework must have
>    a 'select DMA_SHARED_BUFFER' in their respective Kconfigs.
>  
> +- To avoid the wrath of userspace library writers exporting subsystems must have
> +  a flag parameter in the ioctl that creates the dma-buf fd which needs to
> +  support at least the O_CLOEXEC fd flag. This needs to be passed in the flag
> +  parameter of dma_buf_fd. Without any other reasons applying it is recommended
> +  that exporters limit the flags passed to dma_buf_fd to only O_CLOEXEC.

Difficult to parse. Needs more punctuation.

-- 
Ville Syrjälä
Intel OTC
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