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Commit 2a3eb51e authored by Henry Willard's avatar Henry Willard Committed by Rafael J. Wysocki
Browse files

cpufreq: governor: Avoid accessing invalid governor_data 



If cppc_cpufreq.ko is deleted at the same time that tuned-adm is
changing profiles, there is a small chance that a race can occur
between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits()
resulting in a system failure when the latter tries to use
policy->governor_data that has been freed by the former.

This patch uses gov_dbs_data_mutex to synchronize access.

Fixes: e788892b (cpufreq: governor: Get rid of governor events)
Signed-off-by: default avatarHenry Willard <henry.willard@oracle.com>
[ rjw: Subject, minor white space adjustment ]
Cc: 4.8+ <stable@vger.kernel.org> # 4.8+
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent b018fc98

drivers/cpufreq/cpufreq_governor.c

+10 −2
Original line number Diff line number Diff line
@@ -555,12 +555,20 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop); 


void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)

{

	struct policy_dbs_info *policy_dbs = policy->governor_data;

	struct policy_dbs_info *policy_dbs;



	/* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */

	mutex_lock(&gov_dbs_data_mutex);

	policy_dbs = policy->governor_data;

	if (!policy_dbs)

		goto out;



	mutex_lock(&policy_dbs->update_mutex);

	cpufreq_policy_apply_limits(policy);

	gov_update_sample_delay(policy_dbs, 0);



	mutex_unlock(&policy_dbs->update_mutex);



out:

	mutex_unlock(&gov_dbs_data_mutex);

}

EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);