On Mon, 9 Apr 2007 22:31:08 -0400 Dave Jones <[EMAIL PROTECTED]> wrote:
> On Mon, Apr 09, 2007 at 05:26:51PM -0700, Andrew Morton wrote: > > On Thu, 5 Apr 2007 16:50:34 -0400 > > Dave Jones <[EMAIL PROTECTED]> 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? set_cpus_allowed() will only sleep in special circumstances: when we're telling the target task that it is not allwed to run on a CPU upon which it is presently executing. So it needs to be synchronously migrated off that CPU, which requires that the set_cpus_allowed() caller block. You're probably just not hitting that case. Probably we should have a might_sleep() in set_cpus_allowed(), although there might be callers who are guaranteeed to never hit that case and who might legitimately want special treatment to avoid the warning. > [which may be 'the obvious', you wouldn't believe the evening I've had > involving gas leaks and noxious fumes. Wheee, floaty head.] Yeah, I get a lot of patches like that. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/