Re: [PATCH v3 6/6] dma-buf: Check status of enable-signaling bit on debug

From: Christian König
Date: Mon Sep 12 2022 - 04:49:17 EST

Am 09.09.22 um 19:08 schrieb Arvind Yadav:
Fence signaling must be enabled to make sure that
the dma_fence_is_signaled() function ever returns true.
Since drivers and implementations sometimes mess this up,
this ensures correct behaviour when DEBUG_WW_MUTEX_SLOWPATH
is used during debugging.
This should make any implementation bugs resulting in not
signaled fences much more obvious.

Signed-off-by: Arvind Yadav <Arvind.Yadav@xxxxxxx>

Changes in v1,v2 :
1- Addressing Christian's comment to replace
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)

As by review comment from Tvrtko Ursulin let's add a separate config option for this into drivers/dma-buf/Kconfig


+ if (!test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))
+ return false;
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return true;