Messages in this thread |  | | Date | Tue, 23 Jun 2009 07:50:48 -0700 | From | Arjan van de Ven <> | Subject | Re: kerneloops.org report for the week of June 14 2009 |
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On Tue, 23 Jun 2009 13:55:10 +0200 Ingo Molnar <mingo@elte.hu> wrote:
> > * Thomas Gleixner <tglx@linutronix.de> wrote: > > > On Sun, 14 Jun 2009, Arjan van de Ven wrote: > > > Rank 3: getnstimeofday (warning) > > > Reported 309 times (2446 total reports) > > > [suspend resume] getnstimeofday() is called before > > > timekeeping is > > resumed > > > > > Rank 6: hres_timers_resume (warning) > > > Reported 188 times (1024 total reports) > > > [suspend resume] hres_timers_resume() is incorrectly > > > called with interrupts on > > > > Both have the same root cause. Something enables interrupts in the > > early resume path. IIRC, there was a culprit identified recently. > > Rafael ? > > This can be debugged automatically today, using lockdep, by using a > 'helper lock': > > static DEFINE_PER_CPU(struct lockdep_map, helper_lock); > > Then mark the lock irq-safe by doing something like: > > static void mark_lock_irqsafe(void) > { > unsigned long flags; > int cpu; > > local_irq_save(flags); > irq_enter(0); > > for_each_online_cpu(cpu) { > lock_acquire(&per_cpu(helper_lock, cpu), 0, 0, 0, 0, > NULL, 0); lock_release(&per_cpu(helper_lock, cpu), 0, 0, 0, 0, NULL, > 0); } > > irq_exit(0); > local_irq_restore(flags); > } > > Then, the resume path, when it disables irqs, you can disallow > irq-enable via: > > local_irq_disable(); > lock_acquire(&__get_cpu_var(helper_lock), 0, 0, 0, 0, NULL, > 0); ... > <extensive suspend or resume codepaths, callbacks> > ... > lock_release(&__get_cpu_var(helper_lock), 0, 0, 0, 0, NULL, > 0); local_irq_enable(); > > And lockdep will warn if any function inbetween enables IRQs, by > emitting a splat about incorrectly enabled hardirqs. It will warn > about the specific place and will emit a relevant backtrace, - not > just the handler in general.
looks like an interesting approach; it'll pinpoint the bad guy exactly where he's enabling interrupts.. (assuming he's using kernel facilities of course)
-- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org
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