From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Tue, 17 Sep 2013 04:52:11 +0000 (+0530)
Subject: cpufreq: unlock correct rwsem while updating policy->cpu
X-Git-Tag: v3.12-rc2~7^2^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8efd57657d8ef666810b55e609da72de92314dc4;p=pandora-kernel.git

cpufreq: unlock correct rwsem while updating policy->cpu

Current code looks like this:

        WARN_ON(lock_policy_rwsem_write(cpu));
        update_policy_cpu(policy, new_cpu);
        unlock_policy_rwsem_write(cpu);

{lock|unlock}_policy_rwsem_write(cpu) takes/releases policy->cpu's rwsem.
Because cpu is changing with the call to update_policy_cpu(), the
unlock_policy_rwsem_write() will release the incorrect lock.

The right solution would be to release the same lock as was taken earlier. Also
update_policy_cpu() was also called from cpufreq_add_dev() without any locks and
so its better if we move this locking to inside update_policy_cpu().

This patch fixes a regression introduced in 3.12 by commit f9ba680d23
(cpufreq: Extract the handover of policy cpu to a helper function).

Reported-and-tested-by: Jon Medhurst<tixy@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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