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FROMGIT: dma-buf: insert memory barrier before updating num_fences

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smp_store_mb() inserts memory barrier after storing operation.
It is different with what the comment is originally aiming so Null
pointer dereference can be happened if memory update is reordered.

Signed-off-by: Hyejeong Choi <hjeong.choi@samsung.com>

Bug: 417615398
(cherry picked from commit 72c7d62583ebce7baeb61acce6057c361f73be4a
 https://gitlab.freedesktop.org/drm/misc/kernel.git drm-misc-fixes)
Change-Id: I7a984743f929fb8120d0efcf991087e4f8d489ae
Signed-off-by: Hyejeong Choi <hjeong.choi@samsung.com>
This commit is contained in:
Hyejeong Choi
2025-05-12 05:16:37 -05:00
committed by Treehugger Robot
parent 85856ec8b2
commit acc91ef94b
1 changed files with 3 additions and 2 deletions
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5
drivers/dma-buf/dma-resv.c
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@@ -320,8 +320,9 @@ void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
count++;
dma_resv_list_set(fobj, i, fence, usage);
/* pointer update must be visible before we extend the num_fences */
smp_store_mb(fobj->num_fences, count);
/* fence update must be visible before we extend the num_fences */
smp_wmb();
fobj->num_fences = count;
}
EXPORT_SYMBOL(dma_resv_add_fence);