From: Petr Machata petrm@mellanox.com
[ Upstream commit 240ce7f6428ff5188b9eedc066e1e4d645b8635f ]
When a child Qdisc is removed from one of the PRIO Qdisc's bands, it is replaced unconditionally by a NOOP qdisc. As a result, any traffic hitting that band gets dropped. That is incorrect--no Qdisc was explicitly added when PRIO was created, and after removal, none should have to be added either.
Fix PRIO by first attempting to create a default Qdisc and only falling back to noop when that fails. This pattern of attempting to create an invisible FIFO, using NOOP only as a fallback, is also seen in other Qdiscs.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Petr Machata petrm@mellanox.com Acked-by: Jiri Pirko jiri@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_prio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/net/sched/sch_prio.c +++ b/net/sched/sch_prio.c @@ -292,8 +292,14 @@ static int prio_graft(struct Qdisc *sch, struct tc_prio_qopt_offload graft_offload; unsigned long band = arg - 1;
- if (new == NULL) - new = &noop_qdisc; + if (!new) { + new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, + TC_H_MAKE(sch->handle, arg), extack); + if (!new) + new = &noop_qdisc; + else + qdisc_hash_add(new, true); + }
*old = qdisc_replace(sch, new, &q->queues[band]);