[PKT_SCHED]: Qdisc drop operation is optional

The drop operation is optional and qdiscs must check if childs support it.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index ba5283204837..7228d30512c7 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -252,9 +252,9 @@ static int netem_requeue(struct sk_buff *skb, struct Qdisc *sch)
 static unsigned int netem_drop(struct Qdisc* sch)
 {
         struct netem_sched_data *q = qdisc_priv(sch);
-        unsigned int len;
+        unsigned int len = 0;
 
-        if ((len = q->qdisc->ops->drop(q->qdisc)) != 0) {
+        if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
                 sch->q.qlen--;
                 sch->qstats.drops++;
         }