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authorVincent Guittot <vincent.guittot@linaro.org>2012-10-23 03:21:49 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2012-11-15 03:36:09 +0400
commitdde8437d06560366d8988c92b5774039ec703864 (patch)
tree80ee897c0964a325be3c2d8a626ff82dd89013b3 /drivers/base
parent77b67063bb6bce6d475e910d3b886a606d0d91f7 (diff)
downloadlinux-dde8437d06560366d8988c92b5774039ec703864.tar.xz
PM / OPP: RCU reclaim
synchronize_rcu() blocks the caller of opp_enable/disbale for a complete grace period. This blocking duration prevents any intensive use of the functions. Replace synchronize_rcu() by call_rcu() which will call our function for freeing the old opp element. The duration of opp_enable() and opp_disable() will be no more dependant of the grace period. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/power/opp.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index d9468642fc41..1211210b15b0 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -65,6 +65,7 @@ struct opp {
unsigned long u_volt;
struct device_opp *dev_opp;
+ struct rcu_head head;
};
/**
@@ -442,6 +443,17 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
}
/**
+ * opp_free_rcu() - helper to clear the struct opp when grace period has
+ * elapsed without blocking the the caller of opp_set_availability
+ */
+static void opp_free_rcu(struct rcu_head *head)
+{
+ struct opp *opp = container_of(head, struct opp, head);
+
+ kfree(opp);
+}
+
+/**
* opp_set_availability() - helper to set the availability of an opp
* @dev: device for which we do this operation
* @freq: OPP frequency to modify availability
@@ -512,7 +524,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
list_replace_rcu(&opp->node, &new_opp->node);
mutex_unlock(&dev_opp_list_lock);
- synchronize_rcu();
+ call_rcu(&opp->head, opp_free_rcu);
/* Notify the change of the OPP availability */
if (availability_req)
@@ -522,13 +534,10 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE,
new_opp);
- /* clean up old opp */
- new_opp = opp;
- goto out;
+ return 0;
unlock:
mutex_unlock(&dev_opp_list_lock);
-out:
kfree(new_opp);
return r;
}