Messages in this thread | | | Date | Sat, 12 May 2007 09:51:45 -0700 | From | Andrew Morton <> | Subject | Re: [patch 3/3] clockevents: Fix resume logic - updated version |
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On Sat, 12 May 2007 13:44:13 +0200 Thomas Gleixner <tglx@linutronix.de> wrote:
> lockdep complains about the lock nesting of clocksource and watchdog > lock in the resume path. Move watchdog resume out of the clocksource > lock. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > > Index: linux-2.6.21/kernel/time/clocksource.c > =================================================================== > --- linux-2.6.21.orig/kernel/time/clocksource.c > +++ linux-2.6.21/kernel/time/clocksource.c > @@ -151,9 +151,11 @@ static void clocksource_watchdog(unsigne > } > static void clocksource_resume_watchdog(void) > { > - spin_lock(&watchdog_lock); > + unsigned long flags; > + > + spin_lock_irqsave(&watchdog_lock, flags); > watchdog_resumed = 1; > - spin_unlock(&watchdog_lock); > + spin_unlock_irqrestore(&watchdog_lock, flags); > } > > static void clocksource_check_watchdog(struct clocksource *cs) > @@ -224,9 +226,9 @@ void clocksource_resume(void) > cs->resume(); > } > > - clocksource_resume_watchdog(); > - > spin_unlock_irqrestore(&clocksource_lock, flags); > + > + clocksource_resume_watchdog(); > } >
The locking in clocksource_resume_watchdog looks pretty pointless anyway. Can't we just delete it?
The only thing it can race against is, conceivably,
resumed = watchdog_resumed; if (unlikely(resumed)) watchdog_resumed = 0;
which could be solved by using test_and_clear_bit().
Does anyone have any theories about my lockdep warning? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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