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>
diff --git a/drivers/input/gameport/gameport.c b/drivers/input/gameport/gameport.c
index 46239e4..dbf741c 100644
--- a/drivers/input/gameport/gameport.c
+++ b/drivers/input/gameport/gameport.c
@@ -18,13 +18,11 @@
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/gameport.h>
-#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/delay.h>
-#include <linux/kthread.h>
+#include <linux/workqueue.h>
#include <linux/sched.h> /* HZ */
#include <linux/mutex.h>
-#include <linux/freezer.h>
/*#include <asm/io.h>*/
@@ -234,58 +232,22 @@
static DEFINE_SPINLOCK(gameport_event_lock); /* protects gameport_event_list */
static LIST_HEAD(gameport_event_list);
-static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
-static struct task_struct *gameport_task;
-static int gameport_queue_event(void *object, struct module *owner,
- enum gameport_event_type event_type)
+static struct gameport_event *gameport_get_event(void)
{
+ struct gameport_event *event = NULL;
unsigned long flags;
- struct gameport_event *event;
- int retval = 0;
spin_lock_irqsave(&gameport_event_lock, flags);
- /*
- * Scan event list for the other events for the same gameport port,
- * starting with the most recent one. If event is the same we
- * do not need add new one. If event is of different type we
- * need to add this event and should not look further because
- * we need to preseve sequence of distinct events.
- */
- list_for_each_entry_reverse(event, &gameport_event_list, node) {
- if (event->object == object) {
- if (event->type == event_type)
- goto out;
- break;
- }
+ if (!list_empty(&gameport_event_list)) {
+ event = list_first_entry(&gameport_event_list,
+ struct gameport_event, node);
+ list_del_init(&event->node);
}
- event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
- if (!event) {
- pr_err("Not enough memory to queue event %d\n", event_type);
- retval = -ENOMEM;
- goto out;
- }
-
- if (!try_module_get(owner)) {
- pr_warning("Can't get module reference, dropping event %d\n",
- event_type);
- kfree(event);
- retval = -EINVAL;
- goto out;
- }
-
- event->type = event_type;
- event->object = object;
- event->owner = owner;
-
- list_add_tail(&event->node, &gameport_event_list);
- wake_up(&gameport_wait);
-
-out:
spin_unlock_irqrestore(&gameport_event_lock, flags);
- return retval;
+ return event;
}
static void gameport_free_event(struct gameport_event *event)
@@ -319,24 +281,8 @@
spin_unlock_irqrestore(&gameport_event_lock, flags);
}
-static struct gameport_event *gameport_get_event(void)
-{
- struct gameport_event *event = NULL;
- unsigned long flags;
- spin_lock_irqsave(&gameport_event_lock, flags);
-
- if (!list_empty(&gameport_event_list)) {
- event = list_first_entry(&gameport_event_list,
- struct gameport_event, node);
- list_del_init(&event->node);
- }
-
- spin_unlock_irqrestore(&gameport_event_lock, flags);
- return event;
-}
-
-static void gameport_handle_event(void)
+static void gameport_handle_events(struct work_struct *work)
{
struct gameport_event *event;
@@ -368,6 +314,59 @@
mutex_unlock(&gameport_mutex);
}
+static DECLARE_WORK(gameport_event_work, gameport_handle_events);
+
+static int gameport_queue_event(void *object, struct module *owner,
+ enum gameport_event_type event_type)
+{
+ unsigned long flags;
+ struct gameport_event *event;
+ int retval = 0;
+
+ spin_lock_irqsave(&gameport_event_lock, flags);
+
+ /*
+ * Scan event list for the other events for the same gameport port,
+ * starting with the most recent one. If event is the same we
+ * do not need add new one. If event is of different type we
+ * need to add this event and should not look further because
+ * we need to preserve sequence of distinct events.
+ */
+ list_for_each_entry_reverse(event, &gameport_event_list, node) {
+ if (event->object == object) {
+ if (event->type == event_type)
+ goto out;
+ break;
+ }
+ }
+
+ event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
+ if (!event) {
+ pr_err("Not enough memory to queue event %d\n", event_type);
+ retval = -ENOMEM;
+ goto out;
+ }
+
+ if (!try_module_get(owner)) {
+ pr_warning("Can't get module reference, dropping event %d\n",
+ event_type);
+ kfree(event);
+ retval = -EINVAL;
+ goto out;
+ }
+
+ event->type = event_type;
+ event->object = object;
+ event->owner = owner;
+
+ list_add_tail(&event->node, &gameport_event_list);
+ schedule_work(&gameport_event_work);
+
+out:
+ spin_unlock_irqrestore(&gameport_event_lock, flags);
+ return retval;
+}
+
/*
* Remove all events that have been submitted for a given object,
* be it a gameport port or a driver.
@@ -419,19 +418,6 @@
return child;
}
-static int gameport_thread(void *nothing)
-{
- set_freezable();
- do {
- gameport_handle_event();
- wait_event_freezable(gameport_wait,
- kthread_should_stop() || !list_empty(&gameport_event_list));
- } while (!kthread_should_stop());
-
- return 0;
-}
-
-
/*
* Gameport port operations
*/
@@ -814,13 +800,6 @@
return error;
}
- gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
- if (IS_ERR(gameport_task)) {
- bus_unregister(&gameport_bus);
- error = PTR_ERR(gameport_task);
- pr_err("Failed to start kgameportd, error: %d\n", error);
- return error;
- }
return 0;
}
@@ -828,7 +807,12 @@
static void __exit gameport_exit(void)
{
bus_unregister(&gameport_bus);
- kthread_stop(gameport_task);
+
+ /*
+ * There should not be any outstanding events but work may
+ * still be scheduled so simply cancel it.
+ */
+ cancel_work_sync(&gameport_event_work);
}
subsys_initcall(gameport_init);
