[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 9a2f8e41a26ee9684fdea46adf684e9e88727ed9..87e48a4e105133ca3d0407b5c2d84f1b0e3a72c4 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;
 }