Input: serio - convert to common workqueue instead of a thread
Instead of creating an exclusive thread to handle serio events (which
happen rarely), let's switch to using common workqueue. With the arrival
of concurrency-managed workqueue infrastructure we are not concerned
that our callers or callees also using workqueue (no deadlocks anymore)
and it should reduce total number of threads in the system.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index 405bf21..db5b0bc 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -32,10 +32,9 @@
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/errno.h>
-#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/slab.h>
-#include <linux/kthread.h>
+#include <linux/workqueue.h>
#include <linux/mutex.h>
MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
@@ -44,7 +43,7 @@
/*
* serio_mutex protects entire serio subsystem and is taken every time
- * serio port or driver registrered or unregistered.
+ * serio port or driver registered or unregistered.
*/
static DEFINE_MUTEX(serio_mutex);
@@ -165,8 +164,95 @@
static DEFINE_SPINLOCK(serio_event_lock); /* protects serio_event_list */
static LIST_HEAD(serio_event_list);
-static DECLARE_WAIT_QUEUE_HEAD(serio_wait);
-static struct task_struct *serio_task;
+
+static struct serio_event *serio_get_event(void)
+{
+ struct serio_event *event = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&serio_event_lock, flags);
+
+ if (!list_empty(&serio_event_list)) {
+ event = list_first_entry(&serio_event_list,
+ struct serio_event, node);
+ list_del_init(&event->node);
+ }
+
+ spin_unlock_irqrestore(&serio_event_lock, flags);
+ return event;
+}
+
+static void serio_free_event(struct serio_event *event)
+{
+ module_put(event->owner);
+ kfree(event);
+}
+
+static void serio_remove_duplicate_events(struct serio_event *event)
+{
+ struct serio_event *e, *next;
+ unsigned long flags;
+
+ spin_lock_irqsave(&serio_event_lock, flags);
+
+ list_for_each_entry_safe(e, next, &serio_event_list, node) {
+ if (event->object == e->object) {
+ /*
+ * If this event is of different type we should not
+ * look further - we only suppress duplicate events
+ * that were sent back-to-back.
+ */
+ if (event->type != e->type)
+ break;
+
+ list_del_init(&e->node);
+ serio_free_event(e);
+ }
+ }
+
+ spin_unlock_irqrestore(&serio_event_lock, flags);
+}
+
+static void serio_handle_event(struct work_struct *work)
+{
+ struct serio_event *event;
+
+ mutex_lock(&serio_mutex);
+
+ while ((event = serio_get_event())) {
+
+ switch (event->type) {
+
+ case SERIO_REGISTER_PORT:
+ serio_add_port(event->object);
+ break;
+
+ case SERIO_RECONNECT_PORT:
+ serio_reconnect_port(event->object);
+ break;
+
+ case SERIO_RESCAN_PORT:
+ serio_disconnect_port(event->object);
+ serio_find_driver(event->object);
+ break;
+
+ case SERIO_RECONNECT_SUBTREE:
+ serio_reconnect_subtree(event->object);
+ break;
+
+ case SERIO_ATTACH_DRIVER:
+ serio_attach_driver(event->object);
+ break;
+ }
+
+ serio_remove_duplicate_events(event);
+ serio_free_event(event);
+ }
+
+ mutex_unlock(&serio_mutex);
+}
+
+static DECLARE_WORK(serio_event_work, serio_handle_event);
static int serio_queue_event(void *object, struct module *owner,
enum serio_event_type event_type)
@@ -212,101 +298,13 @@
event->owner = owner;
list_add_tail(&event->node, &serio_event_list);
- wake_up(&serio_wait);
+ schedule_work(&serio_event_work);
out:
spin_unlock_irqrestore(&serio_event_lock, flags);
return retval;
}
-static void serio_free_event(struct serio_event *event)
-{
- module_put(event->owner);
- kfree(event);
-}
-
-static void serio_remove_duplicate_events(struct serio_event *event)
-{
- struct serio_event *e, *next;
- unsigned long flags;
-
- spin_lock_irqsave(&serio_event_lock, flags);
-
- list_for_each_entry_safe(e, next, &serio_event_list, node) {
- if (event->object == e->object) {
- /*
- * If this event is of different type we should not
- * look further - we only suppress duplicate events
- * that were sent back-to-back.
- */
- if (event->type != e->type)
- break;
-
- list_del_init(&e->node);
- serio_free_event(e);
- }
- }
-
- spin_unlock_irqrestore(&serio_event_lock, flags);
-}
-
-
-static struct serio_event *serio_get_event(void)
-{
- struct serio_event *event = NULL;
- unsigned long flags;
-
- spin_lock_irqsave(&serio_event_lock, flags);
-
- if (!list_empty(&serio_event_list)) {
- event = list_first_entry(&serio_event_list,
- struct serio_event, node);
- list_del_init(&event->node);
- }
-
- spin_unlock_irqrestore(&serio_event_lock, flags);
- return event;
-}
-
-static void serio_handle_event(void)
-{
- struct serio_event *event;
-
- mutex_lock(&serio_mutex);
-
- while ((event = serio_get_event())) {
-
- switch (event->type) {
-
- case SERIO_REGISTER_PORT:
- serio_add_port(event->object);
- break;
-
- case SERIO_RECONNECT_PORT:
- serio_reconnect_port(event->object);
- break;
-
- case SERIO_RESCAN_PORT:
- serio_disconnect_port(event->object);
- serio_find_driver(event->object);
- break;
-
- case SERIO_RECONNECT_SUBTREE:
- serio_reconnect_subtree(event->object);
- break;
-
- case SERIO_ATTACH_DRIVER:
- serio_attach_driver(event->object);
- break;
- }
-
- serio_remove_duplicate_events(event);
- serio_free_event(event);
- }
-
- mutex_unlock(&serio_mutex);
-}
-
/*
* Remove all events that have been submitted for a given
* object, be it serio port or driver.
@@ -356,18 +354,6 @@
return child;
}
-static int serio_thread(void *nothing)
-{
- do {
- serio_handle_event();
- wait_event_interruptible(serio_wait,
- kthread_should_stop() || !list_empty(&serio_event_list));
- } while (!kthread_should_stop());
-
- return 0;
-}
-
-
/*
* Serio port operations
*/
@@ -1040,21 +1026,18 @@
return error;
}
- serio_task = kthread_run(serio_thread, NULL, "kseriod");
- if (IS_ERR(serio_task)) {
- bus_unregister(&serio_bus);
- error = PTR_ERR(serio_task);
- pr_err("Failed to start kseriod, error: %d\n", error);
- return error;
- }
-
return 0;
}
static void __exit serio_exit(void)
{
bus_unregister(&serio_bus);
- kthread_stop(serio_task);
+
+ /*
+ * There should not be any outstanding events but work may
+ * still be scheduled so simply cancel it.
+ */
+ cancel_work_sync(&serio_event_work);
}
subsys_initcall(serio_init);
