Commit 49550709 authored by John Stultz's avatar John Stultz Committed by Rafael J. Wysocki
Browse files

PM / wakeup: Use irqsave/irqrestore for events_lock 

Jon Medhurst (Tixy) recently noticed a problem with the
events_lock usage. One of the Android patches that uses
wakeup_sources calls wakeup_source_add() with irqs disabled.
However, the event_lock usage in wakeup_source_add() uses
spin_lock_irq()/spin_unlock_irq(), which reenables interrupts.
This results in lockdep warnings.

The fix is to use spin_lock_irqsave()/spin_lock_irqrestore()
instead for the events_lock.

References: https://bugs.launchpad.net/linaro-landing-team-arm/+bug/1037565


Reported-and-debugged-by: default avatarJon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent 5834ec3a

drivers/base/power/wakeup.c

+11 −6
Original line number Diff line number Diff line
@@ -127,6 +127,8 @@ EXPORT_SYMBOL_GPL(wakeup_source_destroy); 
 */

void wakeup_source_add(struct wakeup_source *ws)

{

	unsigned long flags;



	if (WARN_ON(!ws))

		return;
@@ -135,9 +137,9 @@ void wakeup_source_add(struct wakeup_source *ws) 
	ws->active = false;

	ws->last_time = ktime_get();



	spin_lock_irq(&events_lock);

	spin_lock_irqsave(&events_lock, flags);

	list_add_rcu(&ws->entry, &wakeup_sources);

	spin_unlock_irq(&events_lock);

	spin_unlock_irqrestore(&events_lock, flags);

}

EXPORT_SYMBOL_GPL(wakeup_source_add);
@@ -147,12 +149,14 @@ EXPORT_SYMBOL_GPL(wakeup_source_add); 
 */

void wakeup_source_remove(struct wakeup_source *ws)

{

	unsigned long flags;



	if (WARN_ON(!ws))

		return;



	spin_lock_irq(&events_lock);

	spin_lock_irqsave(&events_lock, flags);

	list_del_rcu(&ws->entry);

	spin_unlock_irq(&events_lock);

	spin_unlock_irqrestore(&events_lock, flags);

	synchronize_rcu();

}

EXPORT_SYMBOL_GPL(wakeup_source_remove);
@@ -752,15 +756,16 @@ bool pm_get_wakeup_count(unsigned int *count, bool block) 
bool pm_save_wakeup_count(unsigned int count)

{

	unsigned int cnt, inpr;

	unsigned long flags;



	events_check_enabled = false;

	spin_lock_irq(&events_lock);

	spin_lock_irqsave(&events_lock, flags);

	split_counters(&cnt, &inpr);

	if (cnt == count && inpr == 0) {

		saved_count = count;

		events_check_enabled = true;

	}

	spin_unlock_irq(&events_lock);

	spin_unlock_irqrestore(&events_lock, flags);

	return events_check_enabled;

}

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