[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>
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index 1641db3..3395ca7 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -165,7 +165,7 @@
for (prio = q->bands-1; prio >= 0; prio--) {
qdisc = q->queues[prio];
- if ((len = qdisc->ops->drop(qdisc)) != 0) {
+ if (qdisc->ops->drop && (len = qdisc->ops->drop(qdisc)) != 0) {
sch->q.qlen--;
return len;
}