Re: [PATCH 3/3] clocksource: fix can not set tsc as clocksource bug
From: Alex Shi
Date: Fri Jul 05 2013 - 02:45:51 EST
On 07/05/2013 01:41 PM, Thomas Gleixner wrote:
>
>>>> > >> > Unlikely, but if we have 3 watched clocksources which have the HRES
>
>>>> > >> > bit set, you'd call 3 times clocksource_select().
>
>> > > Also the reselect must be called outside the watchdog_lock region.
>
> >
>
> > Sorry for stupid, the watchdog_lock used protect watchdog related
>
> > resource. but clocksource_select doesn't touch them. So, I know it isn't
>
> > necessary to put reselect under this lock. Just don't know why the
>
> > reselect *must* be called outside of it?
>
clocksource_select()
>
timekeeping_notify()
>
stop_machine()
>
get_online_cpus()
>
might_sleep()
>
mutex_lock()
>
>
So we need to be in preemptible context when we call clocksource_select().
understand! many thanks!
--
Thanks
Alex
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