Hi Christian,
I'm sorry for digging this one out so late.
On 06.05.2022 16:10, Christian König wrote:
dma_fence_chain containers cleanup signaled fences automatically, so
filter those out from arrays as well.
v2: fix missing walk over the array
v3: massively simplify the patch and actually update the description.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
include/linux/dma-fence-unwrap.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index e7c219da4ed7..a4d342fef8e0 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
* Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
* potential fences in them. If @head is just a normal fence only that one is
* returned.
+ *
+ * Note that signalled fences are opportunistically filtered out, which
+ * means the iteration is potentially over no fence at all.
*/
#define dma_fence_unwrap_for_each(fence, cursor, head) \
for (fence = dma_fence_unwrap_first(head, cursor); fence; \
- fence = dma_fence_unwrap_next(cursor))
+ fence = dma_fence_unwrap_next(cursor)) \
+ if (!dma_fence_is_signaled(fence))
#endif
It looks like this particular patch affects merging Sync Fences, which
is reflected by failing IGT test (igt@sw_sync)[1]. The failing subtests are:
- sync_merge - merging different fences on the same timeline, neither
single nor merged fences are signaled
- sync_merge_same - merging the fence with itself on the same
timeline, the fence didn't signal at all
- sync_multi_timeline_wait - merging different fences on different
timelines; the subtest checks if counting fences of
various states works. Currently, it can only see 2
active fences, 0 signaling (should be 2 active,
1 signaling)
Reverting this commit on the top of drm-tip fixes the issue, but I'm not
sure if it wouldn't impact other places in the code. Please let me know
if I can be of any help.
All the best,
Karolina
---------------------
[1] - reproducible locally, but can be also seen in the CI:
https://intel-gfx-ci.01.org/tree/drm-tip/index.html?testfilter=igt@sw_sync
