[PATCH 19/22] drm/amdgpu: Fix the warning division or modulo by zero for the variable num_xcc_per_xcp

[Lazar, Lijo]

On 5/10/2024 8:20 AM, Jesse Zhang wrote:
> Dividing expression num_xcc_per_xcp which may be zero has undefined behavior.
> 
> Signed-off-by: Jesse Zhang <Jesse.Zhang at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c b/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c
> index 414ea3f560a7..5752c6760992 100644
> --- a/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c
> +++ b/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c
> @@ -522,6 +522,9 @@ static int aqua_vanjaram_switch_partition_mode(struct amdgpu_xcp_mgr *xcp_mgr,
>  		goto unlock;
>  
>  	num_xcc_per_xcp = __aqua_vanjaram_get_xcc_per_xcp(xcp_mgr, mode);
> +	if (!num_xcc_per_xcp)
> +		goto unlock;
> +

This won't happen as the mode is validated before and for each valid
mode a non-zero num_xcc_per_xcp is expected. To satisfy the
warning-checker, before going to unlock use a proper 'ret' value also
(otherwise it will look odd).

Thanks,
Lijo

>  	if (adev->gfx.funcs->switch_partition_mode)
>  		adev->gfx.funcs->switch_partition_mode(xcp_mgr->adev,
>  						       num_xcc_per_xcp);