linux-kernel - Re: [PATCH 78/89] sched/core: Remove the tsk_cpus

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Message-ID: <20170207080647.GS6500@twins.programming.kicks-ass.net>
Date:   Tue, 7 Feb 2017 09:06:47 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>,
        Oleg Nesterov <oleg@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 78/89] sched/core: Remove the tsk_cpus_allowed() wrapper

On Mon, Feb 06, 2017 at 11:03:08PM +0100, Ingo Molnar wrote:
> 
> * Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > > +++ b/arch/powerpc/kernel/smp.c
> > > +++ b/arch/sparc/kernel/sysfs.c
> > > +++ b/drivers/cpufreq/sparc-us2e-cpufreq.c
> > > +++ b/drivers/cpufreq/sparc-us3-cpufreq.c
> 
> > > -	cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
> > > +	cpumask_copy(&cpus_allowed, &current->cpus_allowed);
> > 
> > Note that all those, and this is where I stopped looking, appear broken vs 
> > userspace changing the mask right after.
> 
> But these are pre-existing bugs in code twidding ->cpus_allowed, not caused by my 
> patch, right?

Yes..

> I.e. my changes made you notice pre-existing bugs.

I think I spotted them when I made the tsk_cpus_allowed() thing as well.
Just wanted to call them out again.