diff options
| author | Henry Willard <henry.willard@oracle.com> | 2018-08-14 17:01:02 -0700 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2018-08-16 23:03:29 +0200 |
| commit | 2a3eb51e30b9ac66fe1b75877627a7e4aaeca24a (patch) | |
| tree | 82ebe04aa0d83961db2354dd77e6d9c56a589849 /drivers/cpufreq/cpufreq_governor.c | |
| parent | b018fc9800557bd14a40d69501e19c340eb2c521 (diff) | |
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: e788892ba3cc (cpufreq: governor: Get rid of governor events)
Signed-off-by: Henry Willard <henry.willard@oracle.com>
[ rjw: Subject, minor white space adjustment ]
Cc: 4.8+ <stable@vger.kernel.org> # 4.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/cpufreq_governor.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq_governor.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 1d50e97d49f1..6d53f7d9fc7a 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -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); |