Merge branch 'net-ungraft-prio' (2f806c2a) · Commits · 戴 / test

Petr Machata says: ==================== When ungrafting from PRIO, replace child with FIFO 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. In patch #2, this problem is fixed for 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 some other Qdiscs. The only driver currently offloading PRIO (and thus presumably the only one impacted by this) is mlxsw. Therefore patch #1 extends mlxsw to handle the replacement by an invisible FIFO gracefully. ==================== Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -651,6 +651,13 @@ mlxsw_sp_qdisc_prio_graft(struct mlxsw_sp_port *mlxsw_sp_port,
	mlxsw_sp_port->tclass_qdiscs[tclass_num].handle == p->child_handle)		mlxsw_sp_port->tclass_qdiscs[tclass_num].handle == p->child_handle)
	return 0;		return 0;

			if (!p->child_handle) {
			/* This is an invisible FIFO replacing the original Qdisc.
			* Ignore it--the original Qdisc's destroy will follow.
			*/
			return 0;
			}

	/* See if the grafted qdisc is already offloaded on any tclass. If so,		/* See if the grafted qdisc is already offloaded on any tclass. If so,
	* unoffload it.		* unoffload it.
	*/		*/

net/sched/sch_prio.c

+8 −2

Original line number	Original line	Diff line number	Diff line
	@@ -292,8 +292,14 @@ static int prio_graft(struct Qdisc sch, unsigned long arg, struct Qdisc new,
	struct tc_prio_qopt_offload graft_offload;		struct tc_prio_qopt_offload graft_offload;
	unsigned long band = arg - 1;		unsigned long band = arg - 1;

	if (new == NULL)		if (!new) {
			new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
			TC_H_MAKE(sch->handle, arg), extack);
			if (!new)
	new = &noop_qdisc;		new = &noop_qdisc;
			else
			qdisc_hash_add(new, true);
			}

	*old = qdisc_replace(sch, new, &q->queues[band]);		*old = qdisc_replace(sch, new, &q->queues[band]);

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