linux-kernel - Re: [PATCH v3 1/3] cpufreq: mediatek: using global lock avoid race condition

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Message-ID: <20250321060148.adhxjexpnm4dkpnt@vireshk-i7>
Date: Fri, 21 Mar 2025 11:31:48 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Chun-Jen Tseng (曾俊仁) <Chun-Jen.Tseng@...iatek.com>
Cc: "cw00.choi@...sung.com" <cw00.choi@...sung.com>,
	"rafael@...nel.org" <rafael@...nel.org>,
	Project_Global_Chrome_Upstream_Group <Project_Global_Chrome_Upstream_Group@...iatek.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v3 1/3] cpufreq: mediatek: using global lock avoid race
 condition

On 21-03-25, 05:32, Chun-Jen Tseng (曾俊仁) wrote:
> I add a global lock related to the CCI driver.
> 
> This is because the CCI needs to obtain the frequencies of policy-0 and
> policy-6 to determine its own frequency.
> 
> If policy-0 and policy-6 are set simultaneously, it may cause the CCI
> to select the wrong frequency.
> 
> Therefore, I hope to change the setting flow to the following:
>    policy-0 or policy-6 -> set frequency -> CCI receives notification -
> set CCI frequency

Can you please point to the code where this race exists ? I am not
sure I fully understand it as of now. If the race is present in
another driver, CCI ?, then shouldn't it be fixed there instead ?

-- 
viresh