On 10/17/2012 12:04 AM, Paul E. McKenney wrote:
> 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>
>
Great! Thank you :)
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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