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

[Moger, Babu]

Hi Reinette,

On 8/29/23 15:10, Reinette Chatre wrote:
> 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))


I know it does not hurt to add these checks.  But, it may be unnecessary
considering  cdp_disable() has the check "if (r_hw->cdp_enabled)" already.
Both are same checks. What do you think?
-- 
Thanks
Babu Moger