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cpufreq: Rearrange locking in cpufreq_remove_dev()

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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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
This commit is contained in:
Rafael J. Wysocki 2022-05-11 17:51:39 +02:00
parent fddd8f86df
commit f339f35417
1 changed files with 14 additions and 7 deletions
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21
drivers/cpufreq/cpufreq.c
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@ -1660,18 +1660,25 @@ 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)) {
/* We did light-weight exit earlier, do full tear down now */
if (cpufreq_driver->offline)
cpufreq_driver->exit(policy);
cpufreq_policy_free(policy);
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);
}
/**