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Date: Mon, 9 Apr 2007 22:31:08 -0400 From: Dave Jones <davej@...hat.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: "Jeff V. Merkey" <jmerkey@...fmountaingroup.com>, Linux kernel <linux-kernel@...r.kernel.org>, Venki Pallipadi <venkatesh.pallipadi@...el.com> Subject: Re: Preemption Broken: centrino_target busted under SMP on 2.6.20.4 On Mon, Apr 09, 2007 at 05:26:51PM -0700, Andrew Morton wrote: > On Thu, 5 Apr 2007 16:50:34 -0400 > Dave Jones <davej@...hat.com> wrote: > > > diff --git a/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c b/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c > > index f43b987..824d0a2 100644 > > --- a/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c > > +++ b/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c > > @@ -708,6 +708,7 @@ static int centrino_target (struct cpufreq_policy *policy, > > saved_mask = current->cpus_allowed; > > first_cpu = 1; > > cpus_clear(covered_cpus); > > + preempt_disable(); > > for_each_cpu_mask(j, online_policy_cpus) { > > /* > > * Support for SMP systems. > > @@ -798,6 +799,7 @@ static int centrino_target (struct cpufreq_policy *policy, > > } > > > > migrate_end: > > + preempt_enable(); > > set_cpus_allowed(current, saved_mask); > > return 0; > > } > > This means we'll call set_cpus_allowed() while in atomic state, but > set_cpus_allowed() does sleepy stuff. Puzzled. This diff shouldn't change anything about the context we're in when we call set_cpus_allowed, and as we're not seeing warnings now, I'm not sure what I'm missing? [which may be 'the obvious', you wouldn't believe the evening I've had involving gas leaks and noxious fumes. Wheee, floaty head.] Dave -- http://www.codemonkey.org.uk - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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