Commit 3dcd493f authored Apr 12, 2016 by Lars Persson Committed by David S. Miller Apr 14, 2016

net: sched: do not requeue a NULL skb



A failure in validate_xmit_skb_list() triggered an unconditional call
to dev_requeue_skb with skb=NULL. This slowly grows the queue
discipline's qlen count until all traffic through the queue stops.

We take the optimistic approach and continue running the queue after a
failure since it is unknown if later packets also will fail in the
validate path.

Fixes: 55a93b3e ("qdisc: validate skb without holding lock")
Signed-off-by: Lars Persson <larper@axis.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 309cf37f

net/sched/sch_generic.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -159,12 +159,15 @@ int sch_direct_xmit(struct sk_buff skb, struct Qdisc q,
		if (validate)
		skb = validate_xmit_skb_list(skb, dev);

		if (skb) {
		if (likely(skb)) {
		HARD_TX_LOCK(dev, txq, smp_processor_id());
		if (!netif_xmit_frozen_or_stopped(txq))
		skb = dev_hard_start_xmit(skb, dev, txq, &ret);

		HARD_TX_UNLOCK(dev, txq);
		} else {
		spin_lock(root_lock);
		return qdisc_qlen(q);
		}
		spin_lock(root_lock);