On Wednesday, August 15, 2018 2:01:02 AM CEST Henry Willard wrote:
> 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 <henry.will...@oracle.com>
> ---
> 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);
>
Applied, thanks!
