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@xxxxxxxxxxxxxxxxxx>
> ---
> 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@xxxxxxxxx>
Reviewed-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@xxxxxxxxx>
> 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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