redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

PM / OPP: take RCU lock in dev_pm_opp_get_opp_count 

A lot of callers are missing the fact that dev_pm_opp_get_opp_count
needs to be called under RCU lock. Given that RCU locks can safely be
nested, instead of providing *_locked() API, let's take RCU lock inside
dev_pm_opp_get_opp_count() and leave callers as is.

Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
hifive-unleashed-5.1
Dmitry Torokhov 2014-12-16 15:09:38 -08:00 committed by Rafael J. Wysocki
parent 0fe30da2cb
commit b4718c02f4
1 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/base/power/opp.c
View File

@ -216,9 +216,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
* This function returns the number of available opps if there are any,
* else returns 0 if none or the corresponding error value.
*
* Locking: This function must be called under rcu_read_lock(). This function
* internally references two RCU protected structures: device_opp and opp which
* are safe as long as we are under a common RCU locked section.
* Locking: This function takes rcu_read_lock().
*/
int dev_pm_opp_get_opp_count(struct device *dev)
{
@ -226,13 +224,14 @@ int dev_pm_opp_get_opp_count(struct device *dev)
struct dev_pm_opp *temp_opp;
int count = 0;
opp_rcu_lockdep_assert();
rcu_read_lock();
dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp)) {
int r = PTR_ERR(dev_opp);
dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
return r;
count = PTR_ERR(dev_opp);
dev_err(dev, "%s: device OPP not found (%d)\n",
__func__, count);
goto out_unlock;
}
list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
@ -240,6 +239,8 @@ int dev_pm_opp_get_opp_count(struct device *dev)
count++;
}
out_unlock:
rcu_read_unlock();
return count;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);