[PATCH 4/7] Fix qdisc_watchdog_schedule_range_ns range check

[Erez Geva]

   - As all parameters are unsigned.

   - If 'expires' is bigger than 'last_expires' then the left expression
     overflows.

   - It is better to use addition and check both ends of the range.

Signed-off-by: Erez Geva <erez.geva.ext@xxxxxxxxxxx>
---
 net/sched/sch_api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 2a76a2f5ed88..ebf59ca1faab 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -632,7 +632,8 @@ void qdisc_watchdog_schedule_range_ns(struct qdisc_watchdog *wd, u64 expires,
 		/* If timer is already set in [expires, expires + delta_ns],
 		 * do not reprogram it.
 		 */
-		if (wd->last_expires - expires <= delta_ns)
+		if (wd->last_expires >= expires &&
+		    wd->last_expires <= expires + delta_ns)
 			return;
 	}
 
-- 
2.20.1