svn commit: r315013 - stable/11/sys/kern

[Mark Johnston]

Author: markj
Date: Fri Mar 10 18:53:44 2017
New Revision: 315013
URL: https://svnweb.freebsd.org/changeset/base/315013

Log:
  MFC r314625:
  Fix a ticks comparison in sched_pctcpu_update().

Modified:
  stable/11/sys/kern/sched_ule.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/kern/sched_ule.c
==============================================================================
--- stable/11/sys/kern/sched_ule.c	Fri Mar 10 18:52:37 2017	(r315012)
+++ stable/11/sys/kern/sched_ule.c	Fri Mar 10 18:53:44 2017	(r315013)
@@ -1662,7 +1662,11 @@ sched_pctcpu_update(struct td_sched *ts,
 {
 	int t = ticks;
 
-	if (t - ts->ts_ltick >= SCHED_TICK_TARG) {
+	/*
+	 * The signed difference may be negative if the thread hasn't run for
+	 * over half of the ticks rollover period.
+	 */
+	if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) {
 		ts->ts_ticks = 0;
 		ts->ts_ftick = t - SCHED_TICK_TARG;
 	} else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {