linux-kernel - Re: [PATCH] kernel/sched/cputime: Fix unused value in cputime

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Date:   Wed, 20 Jul 2022 13:33:28 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     zengjx95@...il.com
Cc:     mingo@...hat.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com,
        linux-kernel@...r.kernel.org,
        Zeng Jingxiang <linuszeng@...cent.com>
Subject: Re: [PATCH] kernel/sched/cputime: Fix unused value in
 cputime_adjust()

On Wed, Jul 20, 2022 at 06:29:56PM +0800, zengjx95@...il.com wrote:
> From: Zeng Jingxiang <linuszeng@...cent.com>
> 
> Coverity warns uf an unused value:
> 
> assigned_value: Assign the value of the variable rtime to utime here,
> but that stored value is overwritten before it can be used.
> 568	if (stime == 0) {
> 569		utime = rtime;
> 570		goto update;
> 571	}
> 
> value_overwrite: Overwriting previous write to utime with
> the value of expression rtime - stime.
> 592	utime = rtime - stime;

Coverity is being daft, the compiler has a dead-store-elimination pass.

This way the code is more consistent / easier to ready.