* [PATCH] drm/i915: use READ_ONCE() to read vma->iomap in concurrent environment
@ 2024-01-29 4:34 linke li
2024-03-21 9:49 ` linke li
0 siblings, 1 reply; 2+ messages in thread
From: linke li @ 2024-01-29 4:34 UTC (permalink / raw)
To: airlied, daniel; +Cc: intel-gfx, dri-devel, linke li
In function i915_vma_pin_iomap(), vma->iomap is read using READ_ONCE()
in line 562
562 ptr = READ_ONCE(vma->iomap);
while read directly in line 597
592 if (unlikely(cmpxchg(&vma->iomap, NULL, ptr))) {
593 if (page_unmask_bits(ptr))
594 __i915_gem_object_release_map(vma->obj);
595 else
596 io_mapping_unmap(ptr);
597 ptr = vma->iomap;
There is patch similar to this. https://github.com/torvalds/linux/commit/c1c0ce31b2420d5c173228a2132a492ede03d81f
This patch find two read of same variable while one is protected, another
is not. And READ_ONCE() is added to protect.
Signed-off-by: linke li <lilinke99@qq.com>
---
drivers/gpu/drm/i915/i915_vma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index d09aad34ba37..9fcc11db0505 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -594,7 +594,7 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
__i915_gem_object_release_map(vma->obj);
else
io_mapping_unmap(ptr);
- ptr = vma->iomap;
+ ptr = READ_ONCE(vma->iomap);
}
}
--
2.39.3 (Apple Git-145)
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] drm/i915: use READ_ONCE() to read vma->iomap in concurrent environment
2024-01-29 4:34 [PATCH] drm/i915: use READ_ONCE() to read vma->iomap in concurrent environment linke li
@ 2024-03-21 9:49 ` linke li
0 siblings, 0 replies; 2+ messages in thread
From: linke li @ 2024-03-21 9:49 UTC (permalink / raw)
To: lilinke99; +Cc: airlied, daniel, dri-devel, intel-gfx
Hi, I want to confirm the status of this patch and whether need any
additional information.
^ permalink raw reply [flat|nested] 2+ messages in thread
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