Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f8e0731d authored by Christian König's avatar Christian König Committed by Alex Deucher
Browse files

dma-fence: fix dma_fence_get_rcu_safe v2 



When dma_fence_get_rcu() fails to acquire a reference it doesn't necessary
mean that there is no fence at all.

It usually mean that the fence was replaced by a new one and in this situation
we certainly want to have the new one as result and *NOT* NULL.

v2: Keep extra check after dma_fence_get_rcu().

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1505469187-3565-1-git-send-email-deathsimple@vodafone.de
parent 39e16ba1

include/linux/dma-fence.h

+4 −1
Original line number Diff line number Diff line
@@ -248,9 +248,12 @@ dma_fence_get_rcu_safe(struct dma_fence * __rcu *fencep) 
		struct dma_fence *fence;



		fence = rcu_dereference(*fencep);

		if (!fence || !dma_fence_get_rcu(fence))

		if (!fence)

			return NULL;



		if (!dma_fence_get_rcu(fence))

			continue;



		/* The atomic_inc_not_zero() inside dma_fence_get_rcu()

		 * provides a full memory barrier upon success (such as now).

		 * This is paired with the write barrier from assigning