[PATCH] drm/amdgpu: fix uninitialized variable in amdgpu_fill_buffer()

[PATCH] drm/amdgpu: fix uninitialized variable in amdgpu_fill_buffer()

[Samasth Norway Ananda]

Initialize 'r' to 0 so the function does not return an uninitialized
value when the while loop body is never entered. Current callers always
supply non-zero sized BOs so the loop always executes, but the function
itself does not enforce this and static analysis tools flag the
potential use.

Fixes: 22f7cc752408 ("drm/amdgpu: restructure amdgpu_fill_buffer v2")
Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 15d561e3d87f..44524eb2f74f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -2564,7 +2564,7 @@ int amdgpu_fill_buffer(struct amdgpu_ttm_buffer_entity *entity,
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
 	struct dma_fence *fence = NULL;
 	struct amdgpu_res_cursor dst;
-	int r;
+	int r = 0;
 
 	if (!adev->mman.buffer_funcs_enabled) {
 		dev_err(adev->dev,
-- 
2.50.1

Re: [PATCH] drm/amdgpu: fix uninitialized variable in amdgpu_fill_buffer()

[Christian König]

On 2/5/26 03:16, Samasth Norway Ananda wrote:
> Initialize 'r' to 0 so the function does not return an uninitialized
> value when the while loop body is never entered. Current callers always
> supply non-zero sized BOs so the loop always executes, but the function
> itself does not enforce this and static analysis tools flag the
> potential use.
> 
> Fixes: 22f7cc752408 ("drm/amdgpu: restructure amdgpu_fill_buffer v2")
> Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 15d561e3d87f..44524eb2f74f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -2564,7 +2564,7 @@ int amdgpu_fill_buffer(struct amdgpu_ttm_buffer_entity *entity,
>  	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
>  	struct dma_fence *fence = NULL;
>  	struct amdgpu_res_cursor dst;
> -	int r;
> +	int r = 0;

We usually avoid initializing return variables exactly for the reason that the compiler then can point out code paths missing to set it. So please just initialize it directly before the loop.

This is also not a real issue because the loop is always taken, e.g. zero dst.remaining is not possible, but the compiler or analyzing tool can't know that. So maybe drop the Fixes tag, no real reason to backport this except for cleanup and silencing the warning.

Regards,
Christian.

>  
>  	if (!adev->mman.buffer_funcs_enabled) {
>  		dev_err(adev->dev,