Messages in this thread | | | Date | Wed, 3 Apr 2013 10:55:54 +0530 | Subject | Re: [PATCH v6 1/2] cpufreq: split the cpufreq_driver_lock and use the rcu | From | Viresh Kumar <> |
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On 3 April 2013 04:27, Rafael J. Wysocki <rjw@sisk.pl> wrote: > On Tuesday, April 02, 2013 08:29:12 PM Viresh Kumar wrote: >> On 2 April 2013 20:25, Nathan Zimmer <nzimmer@sgi.com> wrote: >> > The lock is unneeded if we expect register and unregister driver to not be >> > called from muliple threads at once. I didn't make that assumption. >> >> Hmm.. But doesn't rcu part take care of that too?? Two writers >> updating stuff simultaneously? > > RCU doesn't cover that in general. Additional locking is needed to provide > synchronization between writers.
Hmm.. I read the same from rcu documentation now...
Nathan, What about using a single spinlock (instead of two) that will take care of all locking requirements of cpufreq.c ... i.e. both cpufreq_cpu_data and cpufreq_driver_{register|unregister}... We don't need two locks actually.
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