[PATCH v4] pm_qos: make update_request non blocking

[florian@mickler.org]

In order to allow drivers to use pm_qos_update_request from interrupt
context we call the notifiers via schedule_work().

Signed-off-by: Florian Mickler <florian@mickler.org>
---

Well, this would be the schedule_work() alternative. 

 kernel/pm_qos_params.c |   47 ++++++++++++++++++++++++++++++-----------------
 1 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index f42d3f7..296343a 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -40,6 +40,7 @@
 #include <linux/string.h>
 #include <linux/platform_device.h>
 #include <linux/init.h>
+#include <linux/workqueue.h>
 
 #include <linux/uaccess.h>
 
@@ -60,11 +61,13 @@ struct pm_qos_request_list {
 
 static s32 max_compare(s32 v1, s32 v2);
 static s32 min_compare(s32 v1, s32 v2);
+static void update_notify(struct work_struct *work);
 
 struct pm_qos_object {
 	struct pm_qos_request_list requests;
 	struct blocking_notifier_head *notifiers;
 	struct miscdevice pm_qos_power_miscdev;
+	struct work_struct notify;
 	char *name;
 	s32 default_value;
 	atomic_t target_value;
@@ -72,10 +75,12 @@ struct pm_qos_object {
 };
 
 static struct pm_qos_object null_pm_qos;
+
 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
 static struct pm_qos_object cpu_dma_pm_qos = {
 	.requests = {LIST_HEAD_INIT(cpu_dma_pm_qos.requests.list)},
 	.notifiers = &cpu_dma_lat_notifier,
+	.notify = __WORK_INITIALIZER(cpu_dma_pm_qos.notify, update_notify),
 	.name = "cpu_dma_latency",
 	.default_value = 2000 * USEC_PER_SEC,
 	.target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
@@ -86,6 +91,7 @@ static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
 static struct pm_qos_object network_lat_pm_qos = {
 	.requests = {LIST_HEAD_INIT(network_lat_pm_qos.requests.list)},
 	.notifiers = &network_lat_notifier,
+	.notify = __WORK_INITIALIZER(network_lat_pm_qos.notify, update_notify),
 	.name = "network_latency",
 	.default_value = 2000 * USEC_PER_SEC,
 	.target_value = ATOMIC_INIT(2000 * USEC_PER_SEC),
@@ -97,13 +103,14 @@ static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
 static struct pm_qos_object network_throughput_pm_qos = {
 	.requests = {LIST_HEAD_INIT(network_throughput_pm_qos.requests.list)},
 	.notifiers = &network_throughput_notifier,
+	.notify = __WORK_INITIALIZER(network_throughput_pm_qos.notify,
+			update_notify),
 	.name = "network_throughput",
 	.default_value = 0,
 	.target_value = ATOMIC_INIT(0),
 	.comparitor = max_compare
 };
 
-
 static struct pm_qos_object *pm_qos_array[] = {
 	&null_pm_qos,
 	&cpu_dma_pm_qos,
@@ -135,35 +142,40 @@ static s32 min_compare(s32 v1, s32 v2)
 	return min(v1, v2);
 }
 
+static void update_notify(struct work_struct *work)
+{
+	struct pm_qos_object *obj =
+		container_of(work, struct pm_qos_object, notify);
+
+	s32 extreme_value = atomic_read(&obj->target_value);
+	blocking_notifier_call_chain(
+		obj->notifiers,
+			(unsigned long) extreme_value, NULL);
+}
 
 static void update_target(int pm_qos_class)
 {
 	s32 extreme_value;
 	struct pm_qos_request_list *node;
+	struct pm_qos_object *obj = pm_qos_array[pm_qos_class];
 	unsigned long flags;
 	int call_notifier = 0;
 
 	spin_lock_irqsave(&pm_qos_lock, flags);
-	extreme_value = pm_qos_array[pm_qos_class]->default_value;
-	list_for_each_entry(node,
-			&pm_qos_array[pm_qos_class]->requests.list, list) {
-		extreme_value = pm_qos_array[pm_qos_class]->comparitor(
-				extreme_value, node->value);
-	}
-	if (atomic_read(&pm_qos_array[pm_qos_class]->target_value) !=
-			extreme_value) {
+	extreme_value = obj->default_value;
+	list_for_each_entry(node, &obj->requests.list, list)
+		extreme_value = obj->comparitor(extreme_value, node->value);
+
+	if (atomic_read(&obj->target_value) != extreme_value) {
 		call_notifier = 1;
-		atomic_set(&pm_qos_array[pm_qos_class]->target_value,
-				extreme_value);
+		atomic_set(&obj->target_value, extreme_value);
 		pr_debug(KERN_ERR "new target for qos %d is %d\n", pm_qos_class,
-			atomic_read(&pm_qos_array[pm_qos_class]->target_value));
+			atomic_read(&obj->target_value));
 	}
 	spin_unlock_irqrestore(&pm_qos_lock, flags);
 
 	if (call_notifier)
-		blocking_notifier_call_chain(
-				pm_qos_array[pm_qos_class]->notifiers,
-					(unsigned long) extreme_value, NULL);
+		schedule_work(&obj->notify);
 }
 
 static int register_pm_qos_misc(struct pm_qos_object *qos)
@@ -301,7 +313,7 @@ EXPORT_SYMBOL_GPL(pm_qos_remove_request);
  * @pm_qos_class: identifies which qos target changes should be notified.
  * @notifier: notifier block managed by caller.
  *
- * will register the notifier into a notification chain that gets called
+ * Will register the notifier into a notification chain that gets called
  * upon changes to the pm_qos_class target value.
  */
 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
@@ -320,7 +332,7 @@ EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
  * @pm_qos_class: identifies which qos target changes are notified.
  * @notifier: notifier block to be removed.
  *
- * will remove the notifier from the notification chain that gets called
+ * Will remove the notifier from the notification chain that gets called
  * upon changes to the pm_qos_class target value.
  */
 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
@@ -392,6 +404,7 @@ static int __init pm_qos_power_init(void)
 {
 	int ret = 0;
 
+
 	ret = register_pm_qos_misc(&cpu_dma_pm_qos);
 	if (ret < 0) {
 		printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
-- 
1.7.1