Input: gameport - convert to use common workqueue instead of a thread
Instead of creating an exclusive thread to handle gameport events (which happen rarely), let's switch to 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:
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8ee294cd9d
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c44f242064
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@ -18,13 +18,11 @@
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#include <linux/ioport.h>
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#include <linux/init.h>
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#include <linux/gameport.h>
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#include <linux/wait.h>
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#include <linux/slab.h>
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/workqueue.h>
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#include <linux/sched.h> /* HZ */
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#include <linux/mutex.h>
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#include <linux/freezer.h>
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/*#include <asm/io.h>*/
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@ -234,58 +232,22 @@ struct gameport_event {
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static DEFINE_SPINLOCK(gameport_event_lock); /* protects gameport_event_list */
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static LIST_HEAD(gameport_event_list);
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static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
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static struct task_struct *gameport_task;
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static int gameport_queue_event(void *object, struct module *owner,
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enum gameport_event_type event_type)
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static struct gameport_event *gameport_get_event(void)
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{
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struct gameport_event *event = NULL;
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unsigned long flags;
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struct gameport_event *event;
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int retval = 0;
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spin_lock_irqsave(&gameport_event_lock, flags);
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/*
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* Scan event list for the other events for the same gameport port,
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* starting with the most recent one. If event is the same we
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* do not need add new one. If event is of different type we
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* need to add this event and should not look further because
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* we need to preseve sequence of distinct events.
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*/
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list_for_each_entry_reverse(event, &gameport_event_list, node) {
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if (event->object == object) {
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if (event->type == event_type)
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goto out;
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break;
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}
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if (!list_empty(&gameport_event_list)) {
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event = list_first_entry(&gameport_event_list,
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struct gameport_event, node);
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list_del_init(&event->node);
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}
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event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
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if (!event) {
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pr_err("Not enough memory to queue event %d\n", event_type);
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retval = -ENOMEM;
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goto out;
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}
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if (!try_module_get(owner)) {
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pr_warning("Can't get module reference, dropping event %d\n",
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event_type);
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kfree(event);
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retval = -EINVAL;
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goto out;
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}
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event->type = event_type;
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event->object = object;
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event->owner = owner;
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list_add_tail(&event->node, &gameport_event_list);
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wake_up(&gameport_wait);
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out:
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spin_unlock_irqrestore(&gameport_event_lock, flags);
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return retval;
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return event;
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}
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static void gameport_free_event(struct gameport_event *event)
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@ -319,24 +281,8 @@ static void gameport_remove_duplicate_events(struct gameport_event *event)
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spin_unlock_irqrestore(&gameport_event_lock, flags);
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}
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static struct gameport_event *gameport_get_event(void)
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{
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struct gameport_event *event = NULL;
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unsigned long flags;
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spin_lock_irqsave(&gameport_event_lock, flags);
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if (!list_empty(&gameport_event_list)) {
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event = list_first_entry(&gameport_event_list,
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struct gameport_event, node);
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list_del_init(&event->node);
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}
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spin_unlock_irqrestore(&gameport_event_lock, flags);
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return event;
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}
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static void gameport_handle_event(void)
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static void gameport_handle_events(struct work_struct *work)
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{
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struct gameport_event *event;
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@ -368,6 +314,59 @@ static void gameport_handle_event(void)
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mutex_unlock(&gameport_mutex);
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}
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static DECLARE_WORK(gameport_event_work, gameport_handle_events);
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static int gameport_queue_event(void *object, struct module *owner,
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enum gameport_event_type event_type)
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{
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unsigned long flags;
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struct gameport_event *event;
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int retval = 0;
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spin_lock_irqsave(&gameport_event_lock, flags);
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/*
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* Scan event list for the other events for the same gameport port,
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* starting with the most recent one. If event is the same we
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* do not need add new one. If event is of different type we
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* need to add this event and should not look further because
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* we need to preserve sequence of distinct events.
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*/
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list_for_each_entry_reverse(event, &gameport_event_list, node) {
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if (event->object == object) {
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if (event->type == event_type)
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goto out;
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break;
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}
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}
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event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
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if (!event) {
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pr_err("Not enough memory to queue event %d\n", event_type);
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retval = -ENOMEM;
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goto out;
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}
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if (!try_module_get(owner)) {
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pr_warning("Can't get module reference, dropping event %d\n",
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event_type);
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kfree(event);
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retval = -EINVAL;
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goto out;
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}
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event->type = event_type;
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event->object = object;
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event->owner = owner;
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list_add_tail(&event->node, &gameport_event_list);
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schedule_work(&gameport_event_work);
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out:
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spin_unlock_irqrestore(&gameport_event_lock, flags);
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return retval;
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}
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/*
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* Remove all events that have been submitted for a given object,
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* be it a gameport port or a driver.
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@ -419,19 +418,6 @@ static struct gameport *gameport_get_pending_child(struct gameport *parent)
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return child;
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}
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static int gameport_thread(void *nothing)
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{
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set_freezable();
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do {
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gameport_handle_event();
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wait_event_freezable(gameport_wait,
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kthread_should_stop() || !list_empty(&gameport_event_list));
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} while (!kthread_should_stop());
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return 0;
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}
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/*
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* Gameport port operations
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*/
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@ -814,13 +800,6 @@ static int __init gameport_init(void)
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return error;
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}
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gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
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if (IS_ERR(gameport_task)) {
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bus_unregister(&gameport_bus);
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error = PTR_ERR(gameport_task);
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pr_err("Failed to start kgameportd, error: %d\n", error);
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return error;
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}
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return 0;
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}
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@ -828,7 +807,12 @@ static int __init gameport_init(void)
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static void __exit gameport_exit(void)
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{
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bus_unregister(&gameport_bus);
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kthread_stop(gameport_task);
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/*
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* There should not be any outstanding events but work may
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* still be scheduled so simply cancel it.
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*/
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cancel_work_sync(&gameport_event_work);
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}
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subsys_initcall(gameport_init);
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