On Monday, July 15, 2013 03:35:04 PM Srivatsa S. Bhat wrote:
> On 07/15/2013 03:25 PM, Viresh Kumar wrote:
> > Hi Srivatsa,
> >
> > I may be wrong but it looks something is wrong in this patch.
> >
> > On 12 July 2013 03:47, Srivatsa S. Bhat
> > <srivatsa.b...@linux.vnet.ibm.com> wrote:
> >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> >
> >> @@ -1239,29 +1263,40 @@ static int __cpufreq_remove_dev(struct device *dev,
> >> if ((cpus == 1) && (cpufreq_driver->target))
> >> __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT);
> >>
> >> - pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
> >> - cpufreq_cpu_put(data);
> >> + if (!frozen) {
> >> + pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
> >> + cpufreq_cpu_put(data);
> >
> > So, we don't decrement usage count here. But we are still increasing
> > counts on cpufreq_add_dev after resume, isn't it?
> >
> > So, we wouldn't be able to free policy struct once all the cpus of a
> > policy are removed after suspend/resume has happened once.
> >
>
> Actually even I was wondering about this while writing the patch and
> I even tested shutdown after multiple suspend/resume cycles, to verify that
> the refcount is messed up. But surprisingly, things worked just fine.
>
> Logically there should've been a refcount mismatch and things should have
> failed, but everything worked fine during my tests. Apart from suspend/resume
> and shutdown tests, I even tried mixing a few regular CPU hotplug operations
> (echo 0/1 to sysfs online files), but nothing stood out.
>
> Sorry, I forgot to document this in the patch. Either the patch is wrong
> or something else is silently fixing this up. Not sure what is the exact
> situation.
OK, so I'm not going to queue [2-8/8] up until we find out what's going on
here (and until Toralf tells me that it doesn't break his system any more).
I've queued up [1/8] for 3.11 already.
Thanks,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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