On Tue, Oct 16, 2012 at 10:07:15PM +0530, Srivatsa S. Bhat wrote:
> On 10/16/2012 10:01 PM, Paul E. McKenney wrote:
> > On Tue, Oct 16, 2012 at 01:28:10PM +0530, Srivatsa S. Bhat wrote:
> >> The CPU_STARTING notifiers are supposed to be run with irqs disabled. But
> >> the
> >> perf_cpu_notifier() macro invokes them without doing that. Fix it.
> >
> > Color me confused...
>
> Hehe, I believe the context provided by diff tricked you ;-)
> The function I am referring to is perf_cpu_notifier(), not
> perf_event_task_tick() :-)
It did indeed fool me! And indeed, checking the code did indeed show
that the name of interest if perf_cpu_notifier().
When using the correct name, I do indeed find places where it is
called with interrupts enabled. So...
Reviewed-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> Regards,
> Srivatsa S. Bhat
>
> > Isn't perf_event_task_tick() invoked only
> > from scheduler_tick(), which always has interrupts disabled?
> >
> > Or are you needing to invoke it from somewhere else?
> >
> > Thanx, Paul
> >
> >> Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com>
> >> ---
> >>
> >> include/linux/perf_event.h | 3 +++
> >> 1 file changed, 3 insertions(+)
> >>
> >> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> >> index 2e90235..0647805 100644
> >> --- a/include/linux/perf_event.h
> >> +++ b/include/linux/perf_event.h
> >> @@ -803,10 +803,13 @@ static inline void perf_event_task_tick(void)
> >> { }
> >> do {
> >> \
> >> static struct notifier_block fn##_nb __cpuinitdata = \
> >> { .notifier_call = fn, .priority = CPU_PRI_PERF }; \
> >> + unsigned long flags; \
> >> fn(&fn##_nb, (unsigned long)CPU_UP_PREPARE, \
> >> (void *)(unsigned long)smp_processor_id()); \
> >> + local_irq_save(flags); \
> >> fn(&fn##_nb, (unsigned long)CPU_STARTING, \
> >> (void *)(unsigned long)smp_processor_id()); \
> >> + local_irq_restore(flags); \
> >> fn(&fn##_nb, (unsigned long)CPU_ONLINE, \
> >> (void *)(unsigned long)smp_processor_id()); \
> >> register_cpu_notifier(&fn##_nb); \
> >>
>
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