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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: Jon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This commit is contained in:
John Stultz 2012-09-06 23:19:06 +02:00 committed by Rafael J. Wysocki
parent 5834ec3aea
commit 4955070974
1 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/base/power/wakeup.c
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@ -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;
}