linux-kernel - Re: [PATCH] cpufreq: schedutil: Don't ignore limit changes when util is unchanged

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Message-ID: <CAB8ipk-EAALE1bhihF3k8i=uk_cPtDom+dD0KP-U3k=vgVj9ZA@mail.gmail.com>
Date: Fri, 11 Apr 2025 16:21:48 +0800
From: Xuewen Yan <xuewen.yan94@...il.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Sultan Alsawaf <sultan@...neltoast.com>, Stephan Gerhold <stephan.gerhold@...aro.org>, 
	Viresh Kumar <viresh.kumar@...aro.org>, Ingo Molnar <mingo@...hat.com>, 
	Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>, 
	Vincent Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Valentin Schneider <vschneid@...hat.com>, Christian Loehle <christian.loehle@....com>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: schedutil: Don't ignore limit changes when util
 is unchanged

...
>
> AFAICS, after this code modification, a limit change may be missed due
> to a possible race with sugov_limits() which cannot happen if
> sg_policy->limits_changed is only cleared when it is set before
> updating sg_policy->need_freq_update.
>
could the following patch prevent the race?

https://lore.kernel.org/all/CAB8ipk_Ayqmh=Ch2aH2c+i-q+qdiQ317VBH1kOHYN=R9dt6LOw@mail.gmail.com/

Thanks!
Regards