PM / Sleep: Make __pm_stay_awake() delete wakeup source timers

If __pm_stay_awake() is called after __pm_wakeup_event() for the same
wakep source object before its timer expires, it won't cancel the
timer, so the wakeup source will be deactivated from the timer
function as scheduled by __pm_wakeup_event().  In that case
__pm_stay_awake() doesn't have any effect beyond incrementing
the wakeup source's event_count field, although it should cancel
the timer and make the wakeup source stay active until __pm_relax()
is called for it.

To fix this problem make __pm_stay_awake() delete the wakeup source's
timer and ensure that it won't be deactivated from the timer funtion
afterwards by clearing its timer_expires field.

Reported-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index b38bb9afb719..7c5ab70b9ef3 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -344,7 +344,6 @@ static void wakeup_source_activate(struct wakeup_source *ws)
 {
         ws->active = true;
         ws->active_count++;
-        ws->timer_expires = jiffies;
         ws->last_time = ktime_get();
 
         /* Increment the counter of events in progress. */
@@ -365,9 +364,14 @@ void __pm_stay_awake(struct wakeup_source *ws)
                 return;
 
         spin_lock_irqsave(&ws->lock, flags);
+
         ws->event_count++;
         if (!ws->active)
                 wakeup_source_activate(ws);
+
+        del_timer(&ws->timer);
+        ws->timer_expires = 0;
+
         spin_unlock_irqrestore(&ws->lock, flags);
 }
 EXPORT_SYMBOL_GPL(__pm_stay_awake);
@@ -541,7 +545,7 @@ void __pm_wakeup_event(struct wakeup_source *ws, unsigned int msec)
         if (!expires)
                 expires = 1;
 
-        if (time_after(expires, ws->timer_expires)) {
+        if (!ws->timer_expires || time_after(expires, ws->timer_expires)) {
                 mod_timer(&ws->timer, expires);
                 ws->timer_expires = expires;
         }