Re: [PATCH] drm/xe: Fix warning on impossible condition

[Nathan Chancellor <nathan@kernel.org>]

On Mon, Dec 18, 2023 at 08:33:01AM -0800, Lucas De Marchi wrote:
> Having a different value for op is not possible: this is already kept
> out of user-visible warning by the check in xe_wait_user_fence_ioctl()
> if op > MAX_OP. The warning is useful as if this switch() is not update
> when a new op is added, it should be triggered.
> 
> Fix warning as reported by 0-DAY CI Kernel:
> 
> 	drivers/gpu/drm/xe/xe_wait_user_fence.c:46:2: warning: variable 'passed' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
> 
> Closes: https://lore.kernel.org/oe-kbuild-all/202312170357.KPSinwPs-lkp@intel.com/
> Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

I am now seeing this warning in -next, can this be applied as a fix so
that our builds are not broken?

> ---
>  drivers/gpu/drm/xe/xe_wait_user_fence.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_wait_user_fence.c b/drivers/gpu/drm/xe/xe_wait_user_fence.c
> index b0a7896f7fcb..a75eeba7bfe5 100644
> --- a/drivers/gpu/drm/xe/xe_wait_user_fence.c
> +++ b/drivers/gpu/drm/xe/xe_wait_user_fence.c
> @@ -46,6 +46,7 @@ static int do_compare(u64 addr, u64 value, u64 mask, u16 op)
>  		break;
>  	default:
>  		XE_WARN_ON("Not possible");
> +		return -EINVAL;
>  	}
>  
>  	return passed ? 0 : 1;
> -- 
> 2.40.1
>