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 --- 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; }
+Nishanth Menon
Quoting Vincent Guittot (2012-09-12 21:13:33)
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
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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