Re: [PATCH 6.1.y] drm/amd/display: fix NULL checks for adev->dm.dc in amdgpu_dm_fini()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 2a3cfb9a24a28da9cc13d2c525a76548865e182c

WARNING: Author mismatch between patch and upstream commit:
Backport author: <jianqi.ren.cn@windriver.com>
Commit author: Nikita Zhandarovich <n.zhandarovich@fintech.ru>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: e040f1fbe9ab)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  2a3cfb9a24a28 ! 1:  d2c2f56b0642e drm/amd/display: fix NULL checks for adev->dm.dc in amdgpu_dm_fini()
    @@ Metadata
      ## Commit message ##
         drm/amd/display: fix NULL checks for adev->dm.dc in amdgpu_dm_fini()
     
    +    [ Upstream commit 2a3cfb9a24a28da9cc13d2c525a76548865e182c ]
    +
         Since 'adev->dm.dc' in amdgpu_dm_fini() might turn out to be NULL
         before the call to dc_enable_dmub_notifications(), check
         beforehand to ensure there will not be a possible NULL-ptr-deref
    @@ Commit message
         Fixes: 81927e2808be ("drm/amd/display: Support for DMUB AUX")
         Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
         Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    +    Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
     
      ## drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c ##
     @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c: static void amdgpu_dm_fini(struct amdgpu_device *adev)
    - 		adev->dm.hdcp_workqueue = NULL;
    - 	}
    + 		dc_deinit_callbacks(adev->dm.dc);
    + #endif
      
     -	if (adev->dm.dc)
     +	if (adev->dm.dc) {
    - 		dc_deinit_callbacks(adev->dm.dc);
    --
    --	if (adev->dm.dc)
      		dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
     -
     -	if (dc_enable_dmub_notifications(adev->dm.dc)) {
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |