[PATCH RESEND] drm/amd/display: Initialize return value in dm_cache_state()

[PATCH RESEND] drm/amd/display: Initialize return value in dm_cache_state()

[Eslam Khafagy]

Initialize the return variable "r" to 0 in dm_cache_state() to fix
a potential use of uninitialized variable warning.

The return value for this function might not be a PTR_ERR, in casse if
condition fails. In that case we ensure predictable reutrn.

Signed-off-by: Eslam Khafagy <eslam.medhat1993@gmail.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 8e1622bf7a42..6b4f3eb9ce48 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3115,7 +3115,7 @@ static void hpd_rx_irq_work_suspend(struct amdgpu_display_manager *dm)
 
 static int dm_cache_state(struct amdgpu_device *adev)
 {
-	int r;
+	int r = 0;
 
 	adev->dm.cached_state = drm_atomic_helper_suspend(adev_to_drm(adev));
 	if (IS_ERR(adev->dm.cached_state)) {
-- 
2.43.0

Re: [PATCH RESEND] drm/amd/display: Initialize return value in dm_cache_state()

[Mario Limonciello]

On 10/7/2025 5:45 PM, Eslam Khafagy wrote:
> Initialize the return variable "r" to 0 in dm_cache_state() to fix
> a potential use of uninitialized variable warning.
> 
> The return value for this function might not be a PTR_ERR, in casse if
> condition fails. In that case we ensure predictable reutrn.

Can you walk me through your thought process?  I looked at all possible 
returns for drm_atomic_helper_suspend() and they all return ERR_PTR() or 
a state.

So I don't see how the IS_ERR() clause could have a problem.
> 
> Signed-off-by: Eslam Khafagy <eslam.medhat1993@gmail.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 8e1622bf7a42..6b4f3eb9ce48 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3115,7 +3115,7 @@ static void hpd_rx_irq_work_suspend(struct amdgpu_display_manager *dm)
>   
>   static int dm_cache_state(struct amdgpu_device *adev)
>   {
> -	int r;
> +	int r = 0;
>   
>   	adev->dm.cached_state = drm_atomic_helper_suspend(adev_to_drm(adev));
>   	if (IS_ERR(adev->dm.cached_state)) {

Re: [PATCH RESEND] drm/amd/display: Initialize return value in dm_cache_state()

[Eslam Khafagy]

On 10/8/25 05:15, Mario Limonciello wrote:
>
>
> On 10/7/2025 5:45 PM, Eslam Khafagy wrote:
>> Initialize the return variable "r" to 0 in dm_cache_state() to fix
>> a potential use of uninitialized variable warning.
>>
>> The return value for this function might not be a PTR_ERR, in casse if
>> condition fails. In that case we ensure predictable reutrn.
>
> Can you walk me through your thought process?  I looked at all 
> possible returns for drm_atomic_helper_suspend() and they all return 
> ERR_PTR() or a state.
>
> So I don't see how the IS_ERR() clause could have a problem.
Hello ,

Thank you for the response. Initially i was working on warnings via 
coverity scan.
Initially my thinking was just by following the sequence of 
dm_cache_state you can see that there was a potential issue if
drm_atomic_helper_suspend returned a non valid pointer that is not PTR_ERR.

But having a second look after your response, indeed it shouldn't be the 
case. so please feel free to drop this patch.

>>
>> Signed-off-by: Eslam Khafagy <eslam.medhat1993@gmail.com>
>> ---
>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
>> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> index 8e1622bf7a42..6b4f3eb9ce48 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -3115,7 +3115,7 @@ static void hpd_rx_irq_work_suspend(struct 
>> amdgpu_display_manager *dm)
>>     static int dm_cache_state(struct amdgpu_device *adev)
>>   {
>> -    int r;
>> +    int r = 0;
>>         adev->dm.cached_state = 
>> drm_atomic_helper_suspend(adev_to_drm(adev));
>>       if (IS_ERR(adev->dm.cached_state)) {
>