Re: cpufreq_stats NULL deref on second system suspend

Srivatsa S. Bhat
2013-09-11T11:18:38Z

On 09/11/2013 04:15 PM, Viresh Kumar wrote:
> On 11 September 2013 16:14, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>> But I would have solved it differently :)
>>
>> We don't really need to call update_policy_cpu() again and again
>> as we don't really need to update policy->cpu...
>>
>> Rather it would be better to just move following inside
>> cpufreq_policy_alloc():
>
> Half written mail sent :(
>
> What about moving following to cpufreq_policy_alloc():
>
> policy->cpu = cpu;
>
> ??
>

Hmm? The problem is not about merely updating the policy->cpu field; the
main issue is that the existing code was not letting the cpufreq-stats
code know that we updated the policy->cpu under the hood. It is important
for cpufreq-stats to know this because it maintains the reference to its
stats structure by associating it with the policy->cpu. So if policy->cpu
changes under the hood, it loses track of its reference. So we need to
keep that code informed about changes to policy->cpu. Thus, we need to call
update_policy_cpu() in the CPU online path (during resume). I don't see
how we can skip that.

Regards,
Srivatsa S. Bhat