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| author | Rafael J. Wysocki <rjw@sisk.pl> | 2012-02-17 23:39:33 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rjw@sisk.pl> | 2012-03-04 23:08:14 +0100 |
| commit | da863cddd831b0f4bf2d067f8b75254f1be94590 (patch) | |
| tree | f217486238bec611a0c08b88ae64249ba60a544e /drivers/base | |
| parent | d94aff87826ee6aa43032f4c0263482913f4e2c8 (diff) | |
| download | linux-da863cddd831b0f4bf2d067f8b75254f1be94590.tar.gz linux-da863cddd831b0f4bf2d067f8b75254f1be94590.tar.bz2 linux-da863cddd831b0f4bf2d067f8b75254f1be94590.zip | |
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.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c index d279f462d624..b38bb9afb719 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); } /** |