Re: [PATCH] drm/i915/gt: fix unsigned integer to signed assignment

[Jani Nikula]

On Wed, 16 Feb 2022, Jiapeng Chong <jiapeng.chong@xxxxxxxxxxxxxxxxx> wrote:
> Eliminate the follow smatch warning:
>
> drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:4640
> guc_create_virtual() warn: assigning (-2) to unsigned variable
> 've->base.instance'.
>
> drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:4641
> guc_create_virtual() warn: assigning (-2) to unsigned variable
> 've->base.uabi_instance'.
>
> Reported-by: Abaci Robot <abaci@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@xxxxxxxxxxxxxxxxx>

The report seems to be valid, but I don't think this is the fix.

Where do we even check for invalid instance/uabi_instance in code?

BR,
Jani.


> ---
>  drivers/gpu/drm/i915/gt/intel_engine_types.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> index 36365bdbe1ee..dc7cc06c68e7 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> @@ -328,10 +328,10 @@ struct intel_engine_cs {
>  	intel_engine_mask_t logical_mask;
>  
>  	u8 class;
> -	u8 instance;
> +	s8 instance;
>  
>  	u16 uabi_class;
> -	u16 uabi_instance;
> +	s16 uabi_instance;
>  
>  	u32 uabi_capabilities;
>  	u32 context_size;

-- 
Jani Nikula, Intel Open Source Graphics Center