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path: root/drivers/base/power/opp.c
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Diffstat (limited to 'drivers/base/power/opp.c')
-rw-r--r--drivers/base/power/opp.c78
1 files changed, 44 insertions, 34 deletions
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 2d195f3a1998..d24dd614a0bd 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -84,7 +84,11 @@ struct dev_pm_opp {
*
* This is an internal data structure maintaining the link to opps attached to
* a device. This structure is not meant to be shared to users as it is
- * meant for book keeping and private to OPP library
+ * meant for book keeping and private to OPP library.
+ *
+ * Because the opp structures can be used from both rcu and srcu readers, we
+ * need to wait for the grace period of both of them before freeing any
+ * resources. And so we have used kfree_rcu() from within call_srcu() handlers.
*/
struct device_opp {
struct list_head node;
@@ -382,12 +386,34 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
}
EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
+static struct device_opp *add_device_opp(struct device *dev)
+{
+ struct device_opp *dev_opp;
+
+ /*
+ * Allocate a new device OPP table. In the infrequent case where a new
+ * device is needed to be added, we pay this penalty.
+ */
+ dev_opp = kzalloc(sizeof(*dev_opp), GFP_KERNEL);
+ if (!dev_opp)
+ return NULL;
+
+ dev_opp->dev = dev;
+ srcu_init_notifier_head(&dev_opp->srcu_head);
+ INIT_LIST_HEAD(&dev_opp->opp_list);
+
+ /* Secure the device list modification */
+ list_add_rcu(&dev_opp->node, &dev_opp_list);
+ return dev_opp;
+}
+
static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
unsigned long u_volt, bool dynamic)
{
struct device_opp *dev_opp = NULL;
struct dev_pm_opp *opp, *new_opp;
struct list_head *head;
+ int ret;
/* allocate new OPP node */
new_opp = kzalloc(sizeof(*new_opp), GFP_KERNEL);
@@ -400,7 +426,6 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
mutex_lock(&dev_opp_list_lock);
/* populate the opp table */
- new_opp->dev_opp = dev_opp;
new_opp->rate = freq;
new_opp->u_volt = u_volt;
new_opp->available = true;
@@ -409,27 +434,12 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
/* Check for existing list for 'dev' */
dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp)) {
- /*
- * Allocate a new device OPP table. In the infrequent case
- * where a new device is needed to be added, we pay this
- * penalty.
- */
- dev_opp = kzalloc(sizeof(struct device_opp), GFP_KERNEL);
+ dev_opp = add_device_opp(dev);
if (!dev_opp) {
- mutex_unlock(&dev_opp_list_lock);
- kfree(new_opp);
- dev_warn(dev,
- "%s: Unable to create device OPP structure\n",
- __func__);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto free_opp;
}
- dev_opp->dev = dev;
- srcu_init_notifier_head(&dev_opp->srcu_head);
- INIT_LIST_HEAD(&dev_opp->opp_list);
-
- /* Secure the device list modification */
- list_add_rcu(&dev_opp->node, &dev_opp_list);
head = &dev_opp->opp_list;
goto list_add;
}
@@ -448,18 +458,17 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
/* Duplicate OPPs ? */
if (new_opp->rate == opp->rate) {
- int ret = opp->available && new_opp->u_volt == opp->u_volt ?
+ ret = opp->available && new_opp->u_volt == opp->u_volt ?
0 : -EEXIST;
dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
__func__, opp->rate, opp->u_volt, opp->available,
new_opp->rate, new_opp->u_volt, new_opp->available);
- mutex_unlock(&dev_opp_list_lock);
- kfree(new_opp);
- return ret;
+ goto free_opp;
}
list_add:
+ new_opp->dev_opp = dev_opp;
list_add_rcu(&new_opp->node, head);
mutex_unlock(&dev_opp_list_lock);
@@ -469,6 +478,11 @@ list_add:
*/
srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADD, new_opp);
return 0;
+
+free_opp:
+ mutex_unlock(&dev_opp_list_lock);
+ kfree(new_opp);
+ return ret;
}
/**
@@ -511,10 +525,11 @@ static void kfree_device_rcu(struct rcu_head *head)
{
struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head);
- kfree(device_opp);
+ kfree_rcu(device_opp, rcu_head);
}
-void __dev_pm_opp_remove(struct device_opp *dev_opp, struct dev_pm_opp *opp)
+static void __dev_pm_opp_remove(struct device_opp *dev_opp,
+ struct dev_pm_opp *opp)
{
/*
* Notify the changes in the availability of the operable
@@ -592,7 +607,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
static int opp_set_availability(struct device *dev, unsigned long freq,
bool availability_req)
{
- struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
+ struct device_opp *dev_opp;
struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
int r = 0;
@@ -606,12 +621,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
mutex_lock(&dev_opp_list_lock);
/* Find the device_opp */
- list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) {
- if (dev == tmp_dev_opp->dev) {
- dev_opp = tmp_dev_opp;
- break;
- }
- }
+ dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp)) {
r = PTR_ERR(dev_opp);
dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
@@ -768,7 +778,7 @@ EXPORT_SYMBOL_GPL(of_init_opp_table);
*/
void of_free_opp_table(struct device *dev)
{
- struct device_opp *dev_opp = find_device_opp(dev);
+ struct device_opp *dev_opp;
struct dev_pm_opp *opp, *tmp;
/* Check for existing list for 'dev' */