[Intel-gfx] [PATCH 04/10] dma-buf: Report signaled links inside dma-fence-chain

[Venkata Sandeep Dhanalakota]

On 20/04/03 10:12, Chris Wilson wrote:
> Whenever we walk along the dma-fence-chain, we prune signaled links to
> keep the chain nice and tidy. This leads to situations where we can
> prune a link and report the earlier fence as the target seqno --
> violating our own consistency checks that the seqno is not more advanced
> than the last element in a dma-fence-chain.
> 
> Report a NULL fence and success if the seqno has already been signaled.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/dma-buf/dma-fence-chain.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
> index 3d123502ff12..c435bbba851c 100644
> --- a/drivers/dma-buf/dma-fence-chain.c
> +++ b/drivers/dma-buf/dma-fence-chain.c
> @@ -99,6 +99,12 @@ int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno)
>  		return -EINVAL;
>  
>  	dma_fence_chain_for_each(*pfence, &chain->base) {
> +		if ((*pfence)->seqno < seqno) { /* already signaled */
> +			dma_fence_put(*pfence);
> +			*pfence = NULL;
> +			break;
> +		}
> +
Looks good to me.

Tested-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota at intel.com>
Reviewed-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota at intel.com>

>  		if ((*pfence)->context != chain->base.context ||
>  		    to_dma_fence_chain(*pfence)->prev_seqno < seqno)
>  			break;
> @@ -222,6 +228,7 @@ EXPORT_SYMBOL(dma_fence_chain_ops);
>   * @chain: the chain node to initialize
>   * @prev: the previous fence
>   * @fence: the current fence
> + * @seqno: the sequence number (syncpt) of the fence within the chain
>   *
>   * Initialize a new chain node and either start a new chain or add the node to
>   * the existing chain of the previous fence.
> -- 
> 2.20.1
> 
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