Commit f339f354 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: Rearrange locking in cpufreq_remove_dev() 



Currently, cpufreq_remove_dev() invokes the ->exit() driver callback
without holding the policy rwsem which is inconsistent with what
happens if ->exit() is invoked directly from cpufreq_offline().

It also manipulates the real_cpus mask and removes the CPU device
symlink without holding the policy rwsem, but cpufreq_offline() holds
the rwsem around the modifications thereof.

For consistency, modify cpufreq_remove_dev() to hold the policy rwsem
until the ->exit() callback has been called (or it has been determined
that it is not necessary to call it).

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
parent fddd8f86

drivers/cpufreq/cpufreq.c

+14 −7
Original line number Diff line number Diff line
@@ -1660,19 +1660,26 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) 
	if (!policy)

		return;



	down_write(&policy->rwsem);



	if (cpu_online(cpu))

		cpufreq_offline(cpu);

		__cpufreq_offline(cpu, policy);



	remove_cpu_dev_symlink(policy, cpu, dev);



	if (cpumask_empty(policy->real_cpus)) {

	if (!cpumask_empty(policy->real_cpus)) {

		up_write(&policy->rwsem);

		return;

	}



	/* We did light-weight exit earlier, do full tear down now */

	if (cpufreq_driver->offline)

		cpufreq_driver->exit(policy);



	up_write(&policy->rwsem);



	cpufreq_policy_free(policy);

}

}



/**

 * cpufreq_out_of_sync - Fix up actual and saved CPU frequency difference.