On 04/18/2013 08:29 PM, Sasha Levin wrote:
> Hi Liu,
>
> On 04/18/2013 08:10 PM, Liu, Chuansheng wrote:
>>> It seems that with commit "smp: Give WARN()ing when calling
>>>> smp_call_function_many()/single() in serving irq" I'm getting a bunch of
>>>> these:
>> This patch gives the warning even when the smp_call_function_many() is
>> called in softirq context,
>> because it will bring the possible deadlock cases, the example is below:
>> CPUA CPUB
>> spin_lock(&spinlock)
>> Any irq coming, call the irq handler
>> irq_exit()
>> spin_lock_irq(&spinlock)
>> <== Blocking here due to
>> CPUB hold it
>> __do_softirq()
>> run_timer_softirq()
>> timer_cb()
>> call smp_call_function_many()
>> send IPI interrupt to CPUA
>> wait_csd()
>>
>> Then both CPUA and CPUB will be deadlocked here.
>
> Right.
>
> So commit f55a6faa3 ("hrtimer: Provide clock_was_set_delayed()") followed by
> one
> of the commits that used clock_was_set_delayed() may trigger the deadlock
> you've
> described. (cc John Stultz...)
Ping?
Thanks,
Sasha
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