[PATCH] drm/amd/display: Fix -Wuninitialized in dm_helpers_dp_mst_send_payload_allocation()

[Hamza Mahfooz]

On 9/13/23 16:03, Alex Deucher wrote:
> On Wed, Sep 13, 2023 at 3:57 PM Hamza Mahfooz <hamza.mahfooz at amd.com> wrote:
>>
>>
>> On 9/13/23 15:54, Alex Deucher wrote:
>>> On Wed, Sep 13, 2023 at 12:17 PM Hamza Mahfooz <hamza.mahfooz at amd.com> wrote:
>>>>
>>>>
>>>> On 9/13/23 12:10, Nathan Chancellor wrote:
>>>>> When building with clang, there is a warning (or error when
>>>>> CONFIG_WERROR is set):
>>>>>
>>>>>      drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_helpers.c:368:21: error: variable 'old_payload' is uninitialized when used here [-Werror,-Wuninitialized]
>>>>>        368 |                                                  new_payload, old_payload);
>>>>>            |                                                               ^~~~~~~~~~~
>>>>>      drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_helpers.c:344:61: note: initialize the variable 'old_payload' to silence this warning
>>>>>        344 |         struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
>>>>>            |                                                                    ^
>>>>>            |                                                                     = NULL
>>>>>      1 error generated.
>>>>>
>>>>> This variable is not required outside of this function so allocate
>>>>> old_payload on the stack and pass it by reference to
>>>>> dm_helpers_construct_old_payload(), resolving the warning.
>>>>>
>>>>> Closes: https://github.com/ClangBuiltLinux/linux/issues/1931
>>>>> Fixes: 5aa1dfcdf0a4 ("drm/mst: Refactor the flow for payload allocation/removement")
>>>>> Signed-off-by: Nathan Chancellor <nathan at kernel.org>
>>>>
>>>> Reviewed-by: Hamza Mahfooz <hamza.mahfooz at amd.com>
>>>>
>>>> Hm, seems like this was pushed through drm-misc-next and as such our CI
>>>> didn't get a chance to test it.
>>>
>>> Can you push this to drm-misc?  That is where Wayne's patches landed.
>>> If not, I can push it.
>>
>> No need, I cherry-picked Wayne's patches to amd-staging-drm-next and
>> applied Nathan's fix.
> 
> Yes, but we can only have patches go upstream via one tree.  Wayne's
> patches are in drm-misc, so that is where the fix should be.  It's
> fine to have them in amd-staging-drm-next for testing purposes, but I
> won't be upstreaming them via the amdgpu -next tree since they are
> already in drm-misc.

In that case can you push it to drm-misc?

> 
> Alex
> 
>>
>>>
>>> Alex
>>>
>>>
>>>>
>>>>
>>>>> ---
>>>>>     drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 6 +++---
>>>>>     1 file changed, 3 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
>>>>> index 9ad509279b0a..c4c35f6844f4 100644
>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
>>>>> @@ -341,7 +341,7 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>>>>>         struct amdgpu_dm_connector *aconnector;
>>>>>         struct drm_dp_mst_topology_state *mst_state;
>>>>>         struct drm_dp_mst_topology_mgr *mst_mgr;
>>>>> -     struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
>>>>> +     struct drm_dp_mst_atomic_payload *new_payload, old_payload;
>>>>>         enum mst_progress_status set_flag = MST_ALLOCATE_NEW_PAYLOAD;
>>>>>         enum mst_progress_status clr_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
>>>>>         int ret = 0;
>>>>> @@ -365,8 +365,8 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>>>>>                 ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, new_payload);
>>>>>         } else {
>>>>>                 dm_helpers_construct_old_payload(stream->link, mst_state->pbn_div,
>>>>> -                                              new_payload, old_payload);
>>>>> -             drm_dp_remove_payload_part2(mst_mgr, mst_state, old_payload, new_payload);
>>>>> +                                              new_payload, &old_payload);
>>>>> +             drm_dp_remove_payload_part2(mst_mgr, mst_state, &old_payload, new_payload);
>>>>>         }
>>>>>
>>>>>         if (ret) {
>>>>>
>>>>> ---
>>>>> base-commit: 8569c31545385195bdb0c021124e68336e91c693
>>>>> change-id: 20230913-fix-wuninitialized-dm_helpers_dp_mst_send_payload_allocation-c37b33aaad18
>>>>>
>>>>> Best regards,
>>>> --
>>>> Hamza
>>>>
>> --
>> Hamza
>>
-- 
Hamza