linux-kernel - Re: [PATCH v3 7/9] dma-buf/fence-chain: Add fence deadline support

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Date:   Wed, 8 Sep 2021 19:54:16 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
        Daniel Vetter <daniel@...ll.ch>,
        Christian König 
        <ckoenig.leichtzumerken@...il.com>,
        Michel Dänzer <michel@...nzer.net>,
        Pekka Paalanen <ppaalanen@...il.com>,
        Rob Clark <robdclark@...omium.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Christian König <christian.koenig@....com>,
        "open list:SYNC FILE FRAMEWORK" <linux-media@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 7/9] dma-buf/fence-chain: Add fence deadline support

On Fri, Sep 03, 2021 at 11:47:58AM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>  drivers/dma-buf/dma-fence-chain.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
> index 1b4cb3e5cec9..736a9ad3ea6d 100644
> --- a/drivers/dma-buf/dma-fence-chain.c
> +++ b/drivers/dma-buf/dma-fence-chain.c
> @@ -208,6 +208,18 @@ static void dma_fence_chain_release(struct dma_fence *fence)
>  	dma_fence_free(fence);
>  }
>  
> +
> +static void dma_fence_chain_set_deadline(struct dma_fence *fence,
> +					 ktime_t deadline)
> +{
> +	dma_fence_chain_for_each(fence, fence) {
> +		struct dma_fence_chain *chain = to_dma_fence_chain(fence);
> +		struct dma_fence *f = chain ? chain->fence : fence;

Doesn't this just end up calling set_deadline on a chain, potenetially
resulting in recursion? Also I don't think this should ever happen, why
did you add that?
-Daniel

> +
> +		dma_fence_set_deadline(f, deadline);
> +	}
> +}
> +
>  const struct dma_fence_ops dma_fence_chain_ops = {
>  	.use_64bit_seqno = true,
>  	.get_driver_name = dma_fence_chain_get_driver_name,
> @@ -215,6 +227,7 @@ const struct dma_fence_ops dma_fence_chain_ops = {
>  	.enable_signaling = dma_fence_chain_enable_signaling,
>  	.signaled = dma_fence_chain_signaled,
>  	.release = dma_fence_chain_release,
> +	.set_deadline = dma_fence_chain_set_deadline,
>  };
>  EXPORT_SYMBOL(dma_fence_chain_ops);
>  
> -- 
> 2.31.1
> 

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