diff options
| author | viresh kumar <viresh.kumar@linaro.org> | 2013-10-18 19:10:15 +0530 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-10-25 23:54:12 +0200 |
| commit | ad7722dab7292dbc1c4586d701ac226b68122d39 (patch) | |
| tree | 9d66845a9e2f1fbb6c2641d30f89f164724a5f76 /include/linux/cpufreq.h | |
| parent | 19e77c28dbf1972305da0dfeb92a62f83df3a91d (diff) | |
cpufreq: create per policy rwsem instead of per CPU cpu_policy_rwsem
We have per-CPU cpu_policy_rwsem for cpufreq core, but we never use
all of them. We always use rwsem of policy->cpu and so we can
actually make this rwsem per policy instead.
This patch does this change. With this change other tricky situations
are also avoided now, like which lock to take while we are changing
policy->cpu, etc.
Suggested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'include/linux/cpufreq.h')
| -rw-r--r-- | include/linux/cpufreq.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index e8c77d33047..93a8c34d6c7 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -85,6 +85,20 @@ struct cpufreq_policy { struct list_head policy_list; struct kobject kobj; struct completion kobj_unregister; + + /* + * The rules for this semaphore: + * - Any routine that wants to read from the policy structure will + * do a down_read on this semaphore. + * - Any routine that will write to the policy structure and/or may take away + * the policy altogether (eg. CPU hotplug), will hold this lock in write + * mode before doing so. + * + * Additional rules: + * - Lock should not be held across + * __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT); + */ + struct rw_semaphore rwsem; }; /* Only for ACPI */ |