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authorRafael J. Wysocki <rjw@sisk.pl>2012-02-17 23:39:33 +0100
committerRafael J. Wysocki <rjw@sisk.pl>2012-03-04 23:08:14 +0100
commitda863cddd831b0f4bf2d067f8b75254f1be94590 (patch)
treef217486238bec611a0c08b88ae64249ba60a544e /drivers/base
parentd94aff87826ee6aa43032f4c0263482913f4e2c8 (diff)
PM / Sleep: Fix race conditions related to wakeup source timer function
If __pm_wakeup_event() has been used (with a nonzero timeout) to report a wakeup event and then __pm_relax() immediately followed by __pm_stay_awake() is called or __pm_wakeup_event() is called once again for the same wakeup source object before its timer expires, the timer function pm_wakeup_timer_fn() may still be run as a result of the previous __pm_wakeup_event() call. In either of those cases it may mistakenly deactivate the wakeup source that has just been activated. To prevent that from happening, make wakeup_source_deactivate() clear the wakeup source's timer_expires field and make pm_wakeup_timer_fn() check if timer_expires is different from zero and if it's not in future before calling wakeup_source_deactivate() (if timer_expires is 0, it means that the timer has just been deleted and if timer_expires is in future, it means that the timer has just been rescheduled to a different time). Reported-by: Arve Hjønnevåg <arve@android.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/power/wakeup.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index d279f462d62..b38bb9afb71 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -433,6 +433,7 @@ static void wakeup_source_deactivate(struct wakeup_source *ws)
ws->max_time = duration;
del_timer(&ws->timer);
+ ws->timer_expires = 0;
/*
* Increment the counter of registered wakeup events and decrement the
@@ -487,11 +488,22 @@ EXPORT_SYMBOL_GPL(pm_relax);
* pm_wakeup_timer_fn - Delayed finalization of a wakeup event.
* @data: Address of the wakeup source object associated with the event source.
*
- * Call __pm_relax() for the wakeup source whose address is stored in @data.
+ * Call wakeup_source_deactivate() for the wakeup source whose address is stored
+ * in @data if it is currently active and its timer has not been canceled and
+ * the expiration time of the timer is not in future.
*/
static void pm_wakeup_timer_fn(unsigned long data)
{
- __pm_relax((struct wakeup_source *)data);
+ struct wakeup_source *ws = (struct wakeup_source *)data;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ws->lock, flags);
+
+ if (ws->active && ws->timer_expires
+ && time_after_eq(jiffies, ws->timer_expires))
+ wakeup_source_deactivate(ws);
+
+ spin_unlock_irqrestore(&ws->lock, flags);
}
/**