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.guit...@linaro.org>
---
drivers/base/power/opp.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index ac993ea..49e4626 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -64,6 +64,7 @@ struct opp {
unsigned long u_volt;
struct device_opp *dev_opp;
+ struct rcu_head head;
};
/**
@@ -441,6 +442,17 @@ 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
@@ -511,7 +523,7 @@ 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)
@@ -521,13 +533,10 @@ 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;
}
--
1.7.9.5
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