opp: Reduce the size of critical section in _opp_kref_release()

There is a lot of stuff here which can be done outside of the
opp_table->lock, do that. This helps avoiding a circular dependency
lockdeps around debugfs.

Reported-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 9915e84..27a0e49 100644 (file)
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1252,9 +1252,14 @@ void _opp_free(struct dev_pm_opp *opp)
        kfree(opp);
 }
 
-static void _opp_kref_release(struct dev_pm_opp *opp,
-                             struct opp_table *opp_table)
+static void _opp_kref_release(struct kref *kref)
 {
+       struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
+       struct opp_table *opp_table = opp->opp_table;
+
+       list_del(&opp->node);
+       mutex_unlock(&opp_table->lock);
+
        /*
         * Notify the changes in the availability of the operable
         * frequency/voltage list.
@@ -1262,27 +1267,9 @@ static void _opp_kref_release(struct dev_pm_opp *opp,
        blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_REMOVE, opp);
        _of_opp_free_required_opps(opp_table, opp);
        opp_debug_remove_one(opp);
-       list_del(&opp->node);
        kfree(opp);
 }
 
-static void _opp_kref_release_unlocked(struct kref *kref)
-{
-       struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
-       struct opp_table *opp_table = opp->opp_table;
-
-       _opp_kref_release(opp, opp_table);
-}
-
-static void _opp_kref_release_locked(struct kref *kref)
-{
-       struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
-       struct opp_table *opp_table = opp->opp_table;
-
-       _opp_kref_release(opp, opp_table);
-       mutex_unlock(&opp_table->lock);
-}
-
 void dev_pm_opp_get(struct dev_pm_opp *opp)
 {
        kref_get(&opp->kref);
@@ -1290,16 +1277,10 @@ void dev_pm_opp_get(struct dev_pm_opp *opp)
 
 void dev_pm_opp_put(struct dev_pm_opp *opp)
 {
-       kref_put_mutex(&opp->kref, _opp_kref_release_locked,
-                      &opp->opp_table->lock);
+       kref_put_mutex(&opp->kref, _opp_kref_release, &opp->opp_table->lock);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_put);
 
-static void dev_pm_opp_put_unlocked(struct dev_pm_opp *opp)
-{
-       kref_put(&opp->kref, _opp_kref_release_unlocked);
-}
-
 /**
  * dev_pm_opp_remove()  - Remove an OPP from OPP table
  * @dev:       device for which we do this operation
@@ -1343,30 +1324,49 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
 
+static struct dev_pm_opp *_opp_get_next(struct opp_table *opp_table,
+                                       bool dynamic)
+{
+       struct dev_pm_opp *opp = NULL, *temp;
+
+       mutex_lock(&opp_table->lock);
+       list_for_each_entry(temp, &opp_table->opp_list, node) {
+               if (dynamic == temp->dynamic) {
+                       opp = temp;
+                       break;
+               }
+       }
+
+       mutex_unlock(&opp_table->lock);
+       return opp;
+}
+
 bool _opp_remove_all_static(struct opp_table *opp_table)
 {
-       struct dev_pm_opp *opp, *tmp;
-       bool ret = true;
+       struct dev_pm_opp *opp;
 
        mutex_lock(&opp_table->lock);
 
        if (!opp_table->parsed_static_opps) {
-               ret = false;
-               goto unlock;
+               mutex_unlock(&opp_table->lock);
+               return false;
        }
 
-       if (--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);
+       if (--opp_table->parsed_static_opps) {
+               mutex_unlock(&opp_table->lock);
+               return true;
        }
 
-unlock:
        mutex_unlock(&opp_table->lock);
 
-       return ret;
+       /*
+        * Can't remove the OPP from under the lock, debugfs removal needs to
+        * happen lock less to avoid circular dependency issues.
+        */
+       while ((opp = _opp_get_next(opp_table, false)))
+               dev_pm_opp_put(opp);
+
+       return true;
 }
 
 /**
@@ -1378,21 +1378,21 @@ unlock:
 void dev_pm_opp_remove_all_dynamic(struct device *dev)
 {
        struct opp_table *opp_table;
-       struct dev_pm_opp *opp, *temp;
+       struct dev_pm_opp *opp;
        int count = 0;
 
        opp_table = _find_opp_table(dev);
        if (IS_ERR(opp_table))
                return;
 
-       mutex_lock(&opp_table->lock);
-       list_for_each_entry_safe(opp, temp, &opp_table->opp_list, node) {
-               if (opp->dynamic) {
-                       dev_pm_opp_put_unlocked(opp);
-                       count++;
-               }
+       /*
+        * Can't remove the OPP from under the lock, debugfs removal needs to
+        * happen lock less to avoid circular dependency issues.
+        */
+       while ((opp = _opp_get_next(opp_table, true))) {
+               dev_pm_opp_put(opp);
+               count++;
        }
-       mutex_unlock(&opp_table->lock);
 
        /* Drop the references taken by dev_pm_opp_add() */
        while (count--)