[Linaro-mm-sig] [PATCH 2/2] dma-buf: Fix dma_resv_test_signaled.

[Christian König]

Am 15.10.21 um 14:52 schrieb Maarten Lankhorst:
> Op 15-10-2021 om 14:07 schreef Christian König:
>> Am 15.10.21 um 13:57 schrieb Maarten Lankhorst:
>>> Commit 7fa828cb9265 ("dma-buf: use new iterator in dma_resv_test_signaled")
>>> accidentally forgot to test whether the dma-buf is actually signaled, breaking
>>> pretty much everything depending on it.
>> NAK, the dma_resv_for_each_fence_unlocked() returns only unsignaled fences. So the code is correct as it is.
> That seems like it might cause some unexpected behavior when that function is called with one of the fence locks held, if it calls dma_fence_signal().
>
> Could it be changed to only test the signaled bit, in which case this patch would still be useful?

That's exactly what I suggested as well, but Daniel was against that 
because of concerns around barriers.

> Or at least add some lockdep annotations, that fence->lock might be taken. So any hangs would at least be easy to spot with lockdep.

That should be trivial doable.

Christian.

>
> ~Maarten
>
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