linux-kernel - Re: [PATCH v2 3/4] dma-buf/sync_file: add sync_file_get

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Date:	Fri, 1 Jul 2016 14:21:33 +0100
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Gustavo Padovan <gustavo@...ovan.org>
Cc:	dri-devel@...ts.freedesktop.org, marcheu@...gle.com,
	Daniel Stone <daniels@...labora.com>, seanpaul@...gle.com,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	linux-kernel@...r.kernel.org, laurent.pinchart@...asonboard.com,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	John Harrison <John.C.Harrison@...el.com>, m.chehab@...sung.com
Subject: Re: [PATCH v2 3/4] dma-buf/sync_file: add sync_file_get_fence()

On Fri, Jul 01, 2016 at 10:05:06AM -0300, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> 
> Creates a function that given an sync file descriptor returns a
> fence containing all fences in the sync_file.
> 
> v2: Comments by Daniel Vetter
> 	- Adapt to new version of fence_collection_init()
> 	- Hold a reference for the fence we return
> 
> v3:
> 	- Adapt to use fput() directly
> 	- rename to sync_file_get_fence() as we always return one fence
> 
> v4: Adapt to use fence_array
> 
> Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> ---
>  drivers/dma-buf/sync_file.c | 24 ++++++++++++++++++++++++
>  include/linux/sync_file.h   |  1 +
>  2 files changed, 25 insertions(+)
> 
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 12dbf17..3ffaea8 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -116,6 +116,30 @@ err:
>  	return NULL;
>  }
>  
> +/**
> + * sync_file_get_fence - get the fence related to the sync_file fd
> + * @fd:		sync_file fd to get the fence from
> + *
> + * Ensures @fd references a valid sync_file and returns a fence that
> + * represents all fence in the sync_file. On error NULL is returned.
> + */
> +struct fence *sync_file_get_fence(int fd)
> +{
> +	struct sync_file *sync_file;
> +	struct fence *fence;
> +
> +	sync_file = sync_file_fdget(fd);
> +	if (!sync_file)
> +		return NULL;
> +
> +	fence = sync_file->fence;
> +	fence_get(fence);

Or just fence = get_fence(sync_file->fence);

> +	fput(sync_file->file);

Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>

Using fence-array for this works very nicely, as we can then inspect the
fences returned and handle native fences for fd passed around.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre