Re: [PATCH v8 5/8] x86/resctrl: Unwind the errors inside rdt_enable_ctx()

[Reinette Chatre]

Hi Babu,

On 8/21/2023 4:30 PM, Babu Moger wrote:
>  static int rdt_enable_ctx(struct rdt_fs_context *ctx)
>  {
>  	int ret = 0;
>  
> -	if (ctx->enable_cdpl2)
> +	if (ctx->enable_cdpl2) {
>  		ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, true);
> +		if (ret)
> +			goto out_done;
> +	}
>  
> -	if (!ret && ctx->enable_cdpl3)
> +	if (ctx->enable_cdpl3) {
>  		ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, true);
> +		if (ret)
> +			goto out_cdpl2;
> +	}
>  
> -	if (!ret && ctx->enable_mba_mbps)
> +	if (ctx->enable_mba_mbps) {
>  		ret = set_mba_sc(true);
> +		if (ret)
> +			goto out_cdpl3;

An error may be encountered here without CDP ever enabled or just
enabled for L2 or L3. I think that the error unwinding should
take care to not unwind an action that was not done. Considering
the information available I think checking either ctx->enable_...
or the checks used in rdt_disable_ctx() would be ok but for consistency
the resctrl_arch_get_cdp_enabled() checks may be most appropriate.

> +	}
> +
> +	return 0;
>  
> +out_cdpl3:

So here I think there should be a check. 
	if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3))

> +	resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
> +out_cdpl2:

... and here a check:
	if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))

> +	resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
> +out_done:
>  	return ret;
>  }
>  

Reinette