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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>
This commit is contained in:
Dmitry Torokhov 2010-11-15 01:39:57 -08:00
parent ce16a474f6
commit 8ee294cd9d
1 changed files with 98 additions and 115 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

213
drivers/input/serio/serio.c
View File

@ -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 @@ MODULE_LICENSE("GPL");
/*
* 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 @@ struct serio_event {
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 @@ static int serio_queue_event(void *object, struct module *owner,
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 @@ static struct serio *serio_get_pending_child(struct serio *parent)
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 @@ static int __init serio_init(void)
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);