opp: Replace list_kref with a local counter

A kref or refcount isn't the right tool to be used here for counting
number of devices that are sharing the static OPPs created for the OPP
table. For example, we are reinitializing the kref again, after it
reaches a value of 0 and frees the resources, if the static OPPs get
added for the same OPP table structure (as the OPP table structure was
never freed). That is messy and very unclear.

This patch makes parsed_static_opps an unsigned integer and uses it to
count the number of users of the static OPPs. The increment and
decrement to parsed_static_opps is done under opp_table->lock now to
make sure no races are possible if the OPP table is getting added and
removed in parallel (which doesn't happen in practice, but can in
theory).

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 19 insertions, 29 deletions

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index be7a7d332332..ba43e6a3dc0a 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -988,7 +988,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
 	BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head);
 	INIT_LIST_HEAD(&opp_table->opp_list);
 	kref_init(&opp_table->kref);
-	kref_init(&opp_table->list_kref);
 
 	/* Secure the device table modification */
 	list_add(&opp_table->node, &opp_tables);
@@ -1072,33 +1071,6 @@ static void _opp_table_kref_release(struct kref *kref)
 	mutex_unlock(&opp_table_lock);
 }
 
-void _opp_remove_all_static(struct opp_table *opp_table)
-{
-	struct dev_pm_opp *opp, *tmp;
-
-	list_for_each_entry_safe(opp, tmp, &opp_table->opp_list, node) {
-		if (!opp->dynamic)
-			dev_pm_opp_put(opp);
-	}
-
-	opp_table->parsed_static_opps = false;
-}
-
-static void _opp_table_list_kref_release(struct kref *kref)
-{
-	struct opp_table *opp_table = container_of(kref, struct opp_table,
-						   list_kref);
-
-	_opp_remove_all_static(opp_table);
-	mutex_unlock(&opp_table_lock);
-}
-
-void _put_opp_list_kref(struct opp_table *opp_table)
-{
-	kref_put_mutex(&opp_table->list_kref, _opp_table_list_kref_release,
-		       &opp_table_lock);
-}
-
 void dev_pm_opp_put_opp_table(struct opp_table *opp_table)
 {
 	kref_put_mutex(&opp_table->kref, _opp_table_kref_release,
@@ -1202,6 +1174,24 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
 
+void _opp_remove_all_static(struct opp_table *opp_table)
+{
+	struct dev_pm_opp *opp, *tmp;
+
+	mutex_lock(&opp_table->lock);
+
+	if (!opp_table->parsed_static_opps || --opp_table->parsed_static_opps)
+		goto unlock;
+
+	list_for_each_entry_safe(opp, tmp, &opp_table->opp_list, node) {
+		if (!opp->dynamic)
+			dev_pm_opp_put_unlocked(opp);
+	}
+
+unlock:
+	mutex_unlock(&opp_table->lock);
+}
+
 /**
  * dev_pm_opp_remove_all_dynamic() - Remove all dynamically created OPPs
  * @dev:	device for which we do this operation
@@ -2276,7 +2266,7 @@ void _dev_pm_opp_find_and_remove_table(struct device *dev)
 		return;
 	}
 
-	_put_opp_list_kref(opp_table);
+	_opp_remove_all_static(opp_table);
 
 	/* Drop reference taken by _find_opp_table() */
 	dev_pm_opp_put_opp_table(opp_table);