Re: [PATCH v2] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend

From: Saravana Kannan
Date: Tue Jul 15 2014 - 01:37:19 EST

On 07/14/2014 09:35 PM, Viresh Kumar wrote:
On 15 July 2014 00:38, Saravana Kannan <skannan@xxxxxxxxxxxxxx> wrote:
Yeah, it definitely crashes if policy->cpu if an offline cpu. Because the
mutex would be uninitialized if it's stopped after boot or it would never
have been initialized (depending on how you fix policy->cpu at boot).

Look at this snippet on the actual tree and it should be pretty evident.

Yeah, I missed it. So the problem is we initialize timer_mutex's for
policy->cpus. So we need to do that just for policy->cpu and also we don't
need a per-cpu timer_mutex anymore.

Btw, I tried to take a stab at removing any assumption in cpufreq code about policy->cpu being ONLINE. There are 160 instances of those of with 23 are in cpufreq.c

So, even if we are sure cpufreq.c is fine, it's 137 other uses spread across all the other files. I definitely don't want to try and fix those as part of this patch. Way too risky and hard to get the test coverage it would need. Even some of the acpi cpufreq drivers seem to be making this assumption.

Btw, I think v3 is done. I did some testing and it was fine. But made some minor changes. Will test tomorrow to make sure I didn't break anything with the minor changes and then send them out.


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