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From: Grazvydas Ignotas <notasas@gmail.com>
To: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org
Subject: [PATCH] drm/amdgpu: fix fence slab teardown
Date: Sun, 23 Oct 2016 21:31:43 +0300	[thread overview]
Message-ID: <1477247507-11378-1-git-send-email-notasas@gmail.com> (raw)

To free fences, call_rcu() is used, which calls amdgpu_fence_free()
after a grace period. During teardown, there is no guarantee all
callbacks have finished, so amdgpu_fence_slab may be destroyed before
all fences have been freed. If we are lucky, this results in some slab
warnings, if not, we get a crash in one of rcu threads because callback
is called after amdgpu has already been unloaded.

Fix it with a rcu_barrier().

Fixes: b44135351a3a ("drm/amdgpu: RCU protected amdgpu_fence_release")
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index 3a2e42f..77b34ec 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -68,6 +68,7 @@ int amdgpu_fence_slab_init(void)
 
 void amdgpu_fence_slab_fini(void)
 {
+	rcu_barrier();
 	kmem_cache_destroy(amdgpu_fence_slab);
 }
 /*
-- 
2.7.4

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             reply	other threads:[~2016-10-23 18:31 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-23 18:31 Grazvydas Ignotas [this message]
2016-10-24  2:34 ` [PATCH] drm/amdgpu: fix fence slab teardown zhoucm1
     [not found]   ` <580D731B.5050304-5C7GfCeVMHo@public.gmane.org>
2016-10-24  3:35     ` 答复: " Qu, Jim
2016-10-24  9:32       ` Grazvydas Ignotas
2016-10-24  9:05     ` Christian König
     [not found] ` <1477247507-11378-1-git-send-email-notasas-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-10-24 16:31   ` Alex Deucher

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