cpufreq: Clear policy->cpus bits in __cpufreq_remove_dev_finish()

This broke after a recent change "cedb70a cpufreq: Split __cpufreq_remove_dev()
into two parts" from Srivatsa.

Consider a scenario where we have two CPUs in a policy (0 & 1) and we are
removing CPU 1. On the call to __cpufreq_remove_dev_prepare() we have cleared 1
from policy->cpus and now on a call to __cpufreq_remove_dev_finish() we read
cpumask_weight of policy->cpus, which will come as 1 and this code will behave
as if we are removing the last CPU from policy :)

Fix it by clearing the CPU mask in __cpufreq_remove_dev_finish() instead of
__cpufreq_remove_dev_prepare().

Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 43c24aa..dbfe219 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1125,7 +1125,7 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy,
        int ret;
 
        /* first sibling now owns the new sysfs dir */
-       cpu_dev = get_cpu_device(cpumask_first(policy->cpus));
+       cpu_dev = get_cpu_device(cpumask_any_but(policy->cpus, old_cpu));
 
        /* Don't touch sysfs files during light-weight tear-down */
        if (frozen)
@@ -1189,12 +1189,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
                        policy->governor->name, CPUFREQ_NAME_LEN);
 #endif
 
-       WARN_ON(lock_policy_rwsem_write(cpu));
+       lock_policy_rwsem_read(cpu);
        cpus = cpumask_weight(policy->cpus);
-
-       if (cpus > 1)
-               cpumask_clear_cpu(cpu, policy->cpus);
-       unlock_policy_rwsem_write(cpu);
+       unlock_policy_rwsem_read(cpu);
 
        if (cpu != policy->cpu) {
                if (!frozen)
@@ -1237,9 +1234,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
                return -EINVAL;
        }
 
-       lock_policy_rwsem_read(cpu);
+       WARN_ON(lock_policy_rwsem_write(cpu));
        cpus = cpumask_weight(policy->cpus);
-       unlock_policy_rwsem_read(cpu);
+
+       if (cpus > 1)
+               cpumask_clear_cpu(cpu, policy->cpus);
+       unlock_policy_rwsem_write(cpu);
 
        /* If cpu is last user of policy, free policy */
        if (cpus == 1) {