Am 05.09.22 um 18:35 schrieb Arvind Yadav:
The core DMA-buf framework needs to enable signaling before the fence is signaled. The core DMA-buf framework can forget to enable signaling before the fence is signaled.
This sentence is a bit confusing. I'm not a native speaker of English either, but I suggest something like:
"Fence signaling must be enable to make sure that the dma_fence_is_signaled() function ever returns true."
To avoid this scenario on the debug kernel, check the DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT status bit before checking the signaling bit status to confirm that enable_signaling is enabled.
This describes the implementation, but we should rather describe the background of the change. The implementation should be obvious. Something like this maybe:
" Since drivers and implementations sometimes mess this up enforce correct behavior when DEBUG_WW_MUTEX_SLOWPATH is used during debugging.
This should make any implementations bugs resulting in not signaled fences much more obvious. "
Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com
With the improved commit message this patch is Reviewed-by: Christian König christian.koenig@amd.com
Regards, Christian.
Changes in v1 : 1- Addressing Christian's comment to replace CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS. 2- As per Christian's comment moving this patch at last so The version of this patch is also changed and previously it was [PATCH 1/4]
include/linux/dma-fence.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 775cdc0b4f24..ba1ddc14c5d4 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -428,6 +428,11 @@ dma_fence_is_signaled_locked(struct dma_fence *fence) static inline bool dma_fence_is_signaled(struct dma_fence *fence) { +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
- if (!test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))
return false;+#endif
- if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) return true;