linux-kernel - Re: [PATCH v7 02/15] sched/core: uclamp: Enforce last task UCLAMP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190313161646.fp2gswuqgzi7z7ow@e110439-lin>
Date:   Wed, 13 Mar 2019 16:16:46 +0000
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-api@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Paul Turner <pjt@...gle.com>,
        Quentin Perret <quentin.perret@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Steve Muckle <smuckle@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>
Subject: Re: [PATCH v7 02/15] sched/core: uclamp: Enforce last task UCLAMP_MAX

On 13-Mar 15:12, Peter Zijlstra wrote:
> On Fri, Feb 08, 2019 at 10:05:41AM +0000, Patrick Bellasi wrote:
> > +static inline void uclamp_idle_reset(struct rq *rq, unsigned int clamp_id,
> > +				     unsigned int clamp_value)
> > +{
> > +	/* Reset max-clamp retention only on idle exit */
> > +	if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE))
> > +		return;
> > +
> > +	WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value);
> > +
> > +	/*
> > +	 * This function is called for both UCLAMP_MIN (before) and UCLAMP_MAX
> > +	 * (after). The idle flag is reset only the second time, when we know
> > +	 * that UCLAMP_MIN has been already updated.
> 
> Why do we care? That is, what is this comment trying to tell us.

Right, the code is clear enough, I'll remove this comment.

> 
> > +	 */
> > +	if (clamp_id == UCLAMP_MAX)
> > +		rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
> > +}

-- 
#include <best/regards.h>

Patrick Bellasi