Messages in this thread | | | Date | Tue, 29 Apr 2014 13:34:31 +0530 | Subject | Re: [PATCH v2 5/5] cpufreq: Catch double invocations of cpufreq_freq_transition_begin/end | From | Viresh Kumar <> |
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On 29 April 2014 13:05, Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> wrote: > On 04/29/2014 12:19 PM, Viresh Kumar wrote: >> + WARN_ON(!(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION) >> && (current == policy->transition_task)); >> >> which you already mentioned. > > Yeah, I think we should just go with this. I thought we needed lots of > if-conditions to do exclude these drivers (which would have made it ugly), > but as you pointed above, just this one would suffice.
Okay, I think we can do one more modification here:
>> + WARN_ON(unlikely(!(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION) >> && (current == policy->transition_task)));
> Besides, the cpufreq core doesn't automatically invoke _begin() and > _end() for ASYNC_NOTIFICATION drivers. So that means the probability > that such drivers will hit this problem is extremely low, since the > driver alone is responsible for invoking _begin/_end and hence there > shouldn't be much of a conflict. So I think we should really just > skip ASYNC_NOTIFICATION drivers in this debug infrastructure.
The only way it can happen (I don't hope somebody would be so stupid to call begin twice from target() :)), is via transition notifiers, which in some case starting a new transition..
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