[PKT_SCHED]: netetm: trap infinite loop hange on qlen underflow

Due to bugs in netem (fixed by later patches), it is possible to get qdisc
qlen to go negative. If this happens the CPU ends up spinning forever
in qdisc_run(). So add a BUG_ON() to trap it.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 9a2f8e4..87e48a4 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -179,6 +179,7 @@ requeue:
                netif_schedule(dev);
                return 1;
        }
+       BUG_ON((int) q->q.qlen < 0);
        return q->q.qlen;
 }