On 3 April 2013 04:27, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > On Tuesday, April 02, 2013 08:29:12 PM Viresh Kumar wrote: >> On 2 April 2013 20:25, Nathan Zimmer <nzimmer@xxxxxxx> 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. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html