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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-11-18 13:40:45 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-11-21 14:35:42 +0100 |
| commit | 182e36af0663a1050c42d234a5bf36f084f8c28b (patch) | |
| tree | 9086484c063bb504ae0c56925ab3ceb192922581 | |
| parent | 001c76f05b01cc8ceb2098c9ff5de2609bec7f76 (diff) | |
| download | linux-182e36af0663a1050c42d234a5bf36f084f8c28b.tar.bz2 | |
cpufreq: Avoid using inactive policies
There are two places in the cpufreq core in which low-level driver
callbacks may be invoked for an inactive cpufreq policy, which isn't
guaranteed to work in general. Both are due to possible races with
CPU offline.
First, in cpufreq_get(), the policy may become inactive after
the check against policy->cpus in cpufreq_cpu_get() and before
policy->rwsem is acquired, in which case using it going forward may
not be correct.
Second, an analogous situation is possible in cpufreq_update_policy().
Avoid using inactive policies by adding policy_is_inactive() checks
to the code in the above places.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 6e6c1fb60fbc..ad3b319486bd 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1526,7 +1526,10 @@ unsigned int cpufreq_get(unsigned int cpu) if (policy) { down_read(&policy->rwsem); - ret_freq = __cpufreq_get(policy); + + if (!policy_is_inactive(policy)) + ret_freq = __cpufreq_get(policy); + up_read(&policy->rwsem); cpufreq_cpu_put(policy); @@ -2265,6 +2268,11 @@ int cpufreq_update_policy(unsigned int cpu) down_write(&policy->rwsem); + if (policy_is_inactive(policy)) { + ret = -ENODEV; + goto unlock; + } + pr_debug("updating policy for CPU %u\n", cpu); memcpy(&new_policy, policy, sizeof(*policy)); new_policy.min = policy->user_policy.min; |