Commit 5de376bb authored Apr 09, 2020 by Chris Wilson

dma-buf: Report signaled links inside dma-fence-chain

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@chris-wilson.co.uk>
Tested-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Reviewed-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200409110101.18400-2-chris@chris-wilson.co.uk

parent 29da47cf

drivers/dma-buf/dma-fence-chain.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}

		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.