On 2 February 2015 at 09:08, ethan zhao <ethan.z...@oracle.com> wrote: >> We take cpufreq_driver_lock() here, and so this will >> block thread B. > > No, there is no cpufreq_driver_lock acquired between > > cpufreq_cpu_get() and cpufreq_cpu_put()
I am not saying that the lock is taken between them. But within cpufreq_cpu_get() to make sure policy doesn't get freed while we are doing kobject_get(). >>> beginning the deference of policy Thread B: >>> ... ... __cpufreq_remove_dev_finish() >>> cpufreq_policy_free(policy); >>> >>> >>> Perhaps move policy->rwsem out side the policy structure is a way to >>> avoid >>> it completely. >>> and you could stopping the PPC thread stepping forward as my patch as >>> temporary workaround. >> >> I couldn't understand your problem completely. Apart from giving a >> detailed >> look of what's going on both threads, always specify where the BUG >> actually >> is.. > > The problem is you are using a rwsem inside policy structure to protect its > assessment, that is bad design. What is the current bug you are facing right now, I haven't understood it well. Also a lock within the structure isn't new. Its all over the kernel. I don't understand why you say its a bad design. -- viresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
