From: Lionel Landwerlin lionel.g.landwerlin@intel.com
[ Upstream commit 4cca2e641641767593583749dec26bfebd8f6f2d ]
There was probably a misunderstand on how the dma-fence-chain is supposed to work or what dma_fence_chain_find_seqno() is supposed to return.
dma_fence_chain_find_seqno() is here to give us the fence to wait upon for a particular point in the timeline. The timeline progresses only when all the points prior to a given number have completed.
Signed-off-by: Lionel Landwerlin lionel.g.landwerlin@intel.com Fixes: dc2f7e67a28a5c ("dma-buf: Exercise dma-fence-chain under selftests") Link: https://patchwork.freedesktop.org/patch/372960/ Signed-off-by: Christian König christian.koenig@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma-buf/st-dma-fence-chain.c | 43 ++++++++++++++-------------- 1 file changed, 21 insertions(+), 22 deletions(-)
diff --git a/drivers/dma-buf/st-dma-fence-chain.c b/drivers/dma-buf/st-dma-fence-chain.c index 5d45ba7ba3cd3..9525f7f561194 100644 --- a/drivers/dma-buf/st-dma-fence-chain.c +++ b/drivers/dma-buf/st-dma-fence-chain.c @@ -318,15 +318,16 @@ static int find_out_of_order(void *arg) goto err; }
- if (fence && fence != fc.chains[1]) { + /* + * We signaled the middle fence (2) of the 1-2-3 chain. The behavior + * of the dma-fence-chain is to make us wait for all the fences up to + * the point we want. Since fence 1 is still not signaled, this what + * we should get as fence to wait upon (fence 2 being garbage + * collected during the traversal of the chain). + */ + if (fence != fc.chains[0]) { pr_err("Incorrect chain-fence.seqno:%lld reported for completed seqno:2\n", - fence->seqno); - - dma_fence_get(fence); - err = dma_fence_chain_find_seqno(&fence, 2); - dma_fence_put(fence); - if (err) - pr_err("Reported %d for finding self!\n", err); + fence ? fence->seqno : 0);
err = -EINVAL; } @@ -415,20 +416,18 @@ static int __find_race(void *arg) if (!fence) goto signal;
- err = dma_fence_chain_find_seqno(&fence, seqno); - if (err) { - pr_err("Reported an invalid fence for find-self:%d\n", - seqno); - dma_fence_put(fence); - break; - } - - if (fence->seqno < seqno) { - pr_err("Reported an earlier fence.seqno:%lld for seqno:%d\n", - fence->seqno, seqno); - err = -EINVAL; - dma_fence_put(fence); - break; + /* + * We can only find ourselves if we are on fence we were + * looking for. + */ + if (fence->seqno == seqno) { + err = dma_fence_chain_find_seqno(&fence, seqno); + if (err) { + pr_err("Reported an invalid fence for find-self:%d\n", + seqno); + dma_fence_put(fence); + break; + } }
dma_fence_put(fence);