Messages in this thread | | | Date | Wed, 26 Feb 2014 12:20:26 -0800 | From | Saravana Kannan <> | Subject | Re: [PATCH] cpufreq: Set policy to non-NULL only after all hotplug online work is done |
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On 02/25/2014 10:02 PM, Viresh Kumar wrote: > On 26 February 2014 07:18, Saravana Kannan <skannan@codeaurora.org> wrote: >> On 02/25/2014 02:41 PM, Rafael J. Wysocki wrote: > >>> And is "fully initialized" actually well defined? >> >> The point in add dev/hot plug path after which we will no longer change >> policy fields without sending further CPUFREQ_UPDATE_POLICY_CPU / >> CPUFRE_NOTIFY notifiers. > > Okay.. > >> Pretty much the end of __cpufreq_add_dev() so that it's after: >> - cpufreq_init_policy() >> - And the update of userpolicy fields that after thie init call > > No. In that case it can be considered initialized before cpufreq_init_policy(). > As we do send CPUFREQ_NOTIFY after that from cpufreq_init_policy()-> > cpufreq_set_policy().
Ok, valid hole in my definition of "fully initialized". > > There are two types of fields within policy, some are very basic: cpu/min/max/ > affected_cpus/related_cpus > > some are advanced: sysfs/governors/.. > > And as a rule you have to get policy->rwsem lock before accessing policy > members. We might not have followed it very well for small things like cpu. > > And so if you are doing anything over that, please use a lock and that is > already present in cpufreq_update_policy(). > > With my latest patchset that I sent yesterday, locking is improved and now > a policy will be usable only after the rwsem is released. And that should be > fine. And so making it available in the per-cpu variable after all the necessary > fields are filled looks fine to me. And so I don't think we need to move it > after call to cpufreq_init_policy(maybe a better name to this function is > required)..
I'll take a closer look. Internal tree cpufreq code is in 3.12, so back-porting all the cpufreq changes and testing it can take a bit of time. Will get back on this.
-Saravana
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