Commit 4eb241e5 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: Do not use dynamically allocated objects in pm_wakeup_event() 



Originally, pm_wakeup_event() uses struct delayed_work objects,
allocated with GFP_ATOMIC, to schedule the execution of pm_relax()
in future.  However, as noted by Alan Stern, it is not necessary to
do that, because all pm_wakeup_event() calls can use one static timer
that will always be set to expire at the latest time passed to
pm_wakeup_event().

The modifications are based on the example code posted by Alan.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent ce441011

drivers/base/power/wakeup.c

+37 −19
Original line number Diff line number Diff line
@@ -28,6 +28,11 @@ static unsigned long events_in_progress; 


static DEFINE_SPINLOCK(events_lock);



static void pm_wakeup_timer_fn(unsigned long data);



static DEFINE_TIMER(events_timer, pm_wakeup_timer_fn, 0, 0);

static unsigned long events_timer_expires;



/*

 * The functions below use the observation that each wakeup event starts a

 * period in which the system should not be suspended.  The moment this period
@@ -103,17 +108,22 @@ void pm_relax(void) 
}



/**

 * pm_wakeup_work_fn - Deferred closing of a wakeup event.

 * pm_wakeup_timer_fn - Delayed finalization of a wakeup event.

 *

 * Execute pm_relax() for a wakeup event detected in the past and free the

 * work item object used for queuing up the work.

 * Decrease the counter of wakeup events being processed after it was increased

 * by pm_wakeup_event().

 */

static void pm_wakeup_work_fn(struct work_struct *work)

static void pm_wakeup_timer_fn(unsigned long data)

{

	struct delayed_work *dwork = to_delayed_work(work);

	unsigned long flags;



	pm_relax();

	kfree(dwork);

	spin_lock_irqsave(&events_lock, flags);

	if (events_timer_expires

	    && time_before_eq(events_timer_expires, jiffies)) {

		events_in_progress--;

		events_timer_expires = 0;

	}

	spin_unlock_irqrestore(&events_lock, flags);

}



/**
@@ -123,30 +133,38 @@ static void pm_wakeup_work_fn(struct work_struct *work) 
 *

 * Notify the PM core of a wakeup event (signaled by @dev) that will take

 * approximately @msec milliseconds to be processed by the kernel.  Increment

 * the counter of wakeup events being processed and queue up a work item

 * that will execute pm_relax() for the event after @msec milliseconds.  If @dev

 * is not NULL, the counter of wakeup events related to @dev is incremented too.

 * the counter of registered wakeup events and (if @msec is nonzero) set up

 * the wakeup events timer to execute pm_wakeup_timer_fn() in future (if the

 * timer has not been set up already, increment the counter of wakeup events

 * being processed).  If @dev is not NULL, the counter of wakeup events related

 * to @dev is incremented too.

 *

 * It is safe to call this function from interrupt context.

 */

void pm_wakeup_event(struct device *dev, unsigned int msec)

{

	unsigned long flags;

	struct delayed_work *dwork;



	dwork = msec ? kzalloc(sizeof(*dwork), GFP_ATOMIC) : NULL;



	spin_lock_irqsave(&events_lock, flags);

	event_count++;

	if (dev)

		dev->power.wakeup_count++;



	if (dwork) {

		INIT_DELAYED_WORK(dwork, pm_wakeup_work_fn);

		schedule_delayed_work(dwork, msecs_to_jiffies(msec));

	if (msec) {

		unsigned long expires;



		expires = jiffies + msecs_to_jiffies(msec);

		if (!expires)

			expires = 1;



		if (!events_timer_expires

		    || time_after(expires, events_timer_expires)) {

			if (!events_timer_expires)

				events_in_progress++;

	} else {

		event_count++;



			mod_timer(&events_timer, expires);

			events_timer_expires = expires;

		}

	}

	spin_unlock_irqrestore(&events_lock, flags);

}

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