[PATCH] cpufreq: governor: Protect cpufreq governor_data
From: Henry Willard <hidden>
Date: 2018-08-15 00:01:45
Also in:
lkml
Subsystem:
cpu frequency scaling framework, the rest · Maintainers:
"Rafael J. Wysocki", Viresh Kumar, Linus Torvalds
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. Signed-off-by: Henry Willard <redacted> --- drivers/cpufreq/cpufreq_governor.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 1d50e97d49f1..43416ee55849 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c@@ -555,12 +555,20 @@ void cpufreq_dbs_governor_stop(struct cpufreq_policy *policy) 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);
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1.8.3.1