linux-kernel - Re: [PATCH] x86/resctrl: Fix unneeded variable warning reported by kernel test robot

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Date: Wed, 24 Jan 2024 10:51:49 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Borislav Petkov <bp@...en8.de>
CC: Babu Moger <babu.moger@....com>, <corbet@....net>, <fenghua.yu@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <kim.phillips@....com>, <lukas.bulwahn@...il.com>,
	<seanjc@...gle.com>, <jmattson@...gle.com>, <leitao@...ian.org>,
	<jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
	<kirill.shutemov@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kai.huang@...el.com>, <kan.liang@...ux.intel.com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<sandipan.das@....com>, <ilpo.jarvinen@...ux.intel.com>,
	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>
Subject: Re: [PATCH] x86/resctrl: Fix unneeded variable warning reported by
 kernel test robot

Hi Boris,

On 1/24/2024 10:31 AM, Borislav Petkov wrote:
> On Wed, Jan 24, 2024 at 10:25:17AM -0800, Reinette Chatre wrote:
>> This can be confusing since it implies that the patch you mention
>> introduces the issue but instead the variable has been unneeded since
>> the original:
>> 92bd5a139033 ("x86/resctrl: Add interface to write mbm_total_bytes_config")
> 
> What I said. :)

Right from the start, yes.

> 
>> To help clarify you can mention this order of events and also add an
>> appropriate "Fixes:" tag.
>>
>>> cocci warnings: (new ones prefixed by >>)
>>>>> arch/x86/kernel/cpu/resctrl/rdtgroup.c:1621:5-8: Unneeded variable: "ret". Return "  0" on line 1655
>>>
>>> Fix the warning by removing the variable "ret" and returning 0 directly.
>>
>> cocci warning was spot on*. This fix is not just a change to "make a
>> warning go away" but instead fixing an actual problem.
>> It can just be "Remove the unneeded variable and return 0 directly".
> 
> I'll fix all up before applying.

Thank you very much. For what it is worth, I do agree with the actual fix
and you can add:
Acked-by: Reinette Chatre <reinette.chatre@...el.com>

> 
>> * I'll add a private setup with the goal to catch these earlier.
> 
> Except that it doesn't fire with the patch that added the code. It looks
> like the cocci script needs adjustment...

Reinette