NAK, we already merged a patch to avoid the fence_put() in general when the ring test fails.

Regards,
Christian.

Am 16.08.2016 um 08:33 schrieb Matthew Macy:
Clang identified this when I was merging up 4.8-rc1/rc2. I usually just disable 
warnings as they pop up as I treat the drivers as vendor code and FreeBSD's 
default clang settings are a bit on the anal side. However, this appears to be 
a legitimate bug. I pointed the problem out on #dri-devel and was asked to send 
a patch here.

I haven't submitted patches before, but this is a trivial fix so bear with me.

 From 89ea7621c52ff9d3b6e48fa315609a042f2f5e0d Mon Sep 17 00:00:00 2001
From: Matt Macy <[email protected]>
Date: Mon, 15 Aug 2016 23:22:49 -0700
Subject: [PATCH] drm/amdgpu: fix possible kref_put on random stack value

If amdgpu_uvd_get_create_msg fails fence_put(fence) will be called with
fence uninitialized - possibly leading to kref_put being called on whatever
value happens to be on the stack. Initializing fence to NULL precludes this.

Signed-off-by: Matt Macy [email protected]
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
index b11f4e8..59931d4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
@@ -1161,7 +1161,7 @@ void amdgpu_uvd_ring_end_use(struct amdgpu_ring *ring)
   */
  int amdgpu_uvd_ring_test_ib(struct amdgpu_ring *ring, long timeout)
  {
-       struct fence *fence;
+       struct fence *fence = NULL;
        long r;
r = amdgpu_uvd_get_create_msg(ring, 1, NULL);


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