opal hotel: only delete events that have not yet fired

The opal_hotel_checkout() function (and
_checkout_and_return_occupant()) can be called manually or it can be
invoked by the eviction callback.  When it is invoked by the eviction
callback, we do not want to opal_event_del() the eviction callback.

Author: jsquyres

opal/class/opal_hotel.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2013 Cisco Systems, Inc. All rights reserved.
+ * Copyright (c) 2012-2016 Cisco Systems, Inc.  All rights reserved.
  * Copyright (c) 2012      Los Alamos National Security, LLC. All rights reserved
  * Copyright (c) 2015      Intel, Inc. All rights reserved.
  * $COPYRIGHT$
@@ -245,7 +245,11 @@ static inline void opal_hotel_checkout(opal_hotel_t *hotel, int room_num)
     room = &(hotel->rooms[room_num]);
     if (OPAL_LIKELY(NULL != room->occupant)) {
         room->occupant = NULL;
-        if (NULL != hotel->evbase) {
+        /* Only delete the eviction event if it has not already fired.
+           Specifically: don't delete the event if this function was
+           invoked by the eviction timeout! */
+        if (NULL != hotel->evbase &&
+            opal_event_evtimer_pending(&room->eviction_timer_event, NULL)) {
             opal_event_del(&(room->eviction_timer_event));
         }
         hotel->last_unoccupied_room++;
@@ -282,7 +286,14 @@ static inline void opal_hotel_checkout_and_return_occupant(opal_hotel_t *hotel,
         opal_output (10, "checking out occupant %p from room num %d", room->occupant, room_num);
         *occupant = room->occupant;
         room->occupant = NULL;
-        if (NULL != hotel->evbase) {
+        /* Only delete the eviction event if it has not already fired.
+           Specifically: don't delete the event if this function was
+           invoked by the eviction timeout! (this check is somewhat
+           redundant because as of this writing, the eviction timeout
+           does not call this function, but this is good defensive
+           programming). */
+        if (NULL != hotel->evbase &&
+            opal_event_evtimer_pending(&room->eviction_timer_event, NULL)) {
             opal_event_del(&(room->eviction_timer_event));
         }
         hotel->last_unoccupied_room++;