net: sched: introduce ingress/egress block index attributes for qdisc

Introduce two new attributes to be used for qdisc creation and dumping.
One for ingress block, one for egress block. Introduce a set of ops that
qdisc which supports block sharing would implement.

Passing block indexes in qdisc change is not supported yet and it is
checked and forbidded.

In future, these attributes are to be reused for specifying block
indexes for classes as well. As of this moment however, it is not
supported so a check is in place to forbid it.

Suggested-by: Roopa Prabhu <[e-mail]>
Signed-off-by: Jiri Pirko <[e-mail]>
Acked-by: Jamal Hadi Salim <[e-mail]>
Acked-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/sch_generic.h

···
 	int			(*dump)(struct Qdisc *, struct sk_buff *);
 	int			(*dump_stats)(struct Qdisc *, struct gnet_dump *);
 
+	void			(*ingress_block_set)(struct Qdisc *sch,
+						     u32 block_index);
+	void			(*egress_block_set)(struct Qdisc *sch,
+						    u32 block_index);
+	u32			(*ingress_block_get)(struct Qdisc *sch);
+	u32			(*egress_block_get)(struct Qdisc *sch);
+
 	struct module		*owner;
 };
 

include/uapi/linux/rtnetlink.h

···
 	TCA_DUMP_INVISIBLE,
 	TCA_CHAIN,
 	TCA_HW_OFFLOAD,
+	TCA_INGRESS_BLOCK,
+	TCA_EGRESS_BLOCK,
 	__TCA_MAX
 };
 

net/sched/sch_api.c

···
 	unsigned char *b = skb_tail_pointer(skb);
 	struct gnet_dump d;
 	struct qdisc_size_table *stab;
+	u32 block_index;
 	__u32 qlen;
 
 	cond_resched();
···
 	tcm->tcm_info = refcount_read(&q->refcnt);
 	if (nla_put_string(skb, TCA_KIND, q->ops->id))
 		goto nla_put_failure;
+	if (q->ops->ingress_block_get) {
+		block_index = q->ops->ingress_block_get(q);
+		if (block_index &&
+		    nla_put_u32(skb, TCA_INGRESS_BLOCK, block_index))
+			goto nla_put_failure;
+	}
+	if (q->ops->egress_block_get) {
+		block_index = q->ops->egress_block_get(q);
+		if (block_index &&
+		    nla_put_u32(skb, TCA_EGRESS_BLOCK, block_index))
+			goto nla_put_failure;
+	}
 	if (q->ops->dump && q->ops->dump(q, skb) < 0)
 		goto nla_put_failure;
 	if (nla_put_u8(skb, TCA_HW_OFFLOAD, !!(q->flags & TCQ_F_OFFLOADED)))
···
 	return err;
 }
 
+static int qdisc_block_indexes_set(struct Qdisc *sch, struct nlattr **tca,
+				   struct netlink_ext_ack *extack)
+{
+	u32 block_index;
+
+	if (tca[TCA_INGRESS_BLOCK]) {
+		block_index = nla_get_u32(tca[TCA_INGRESS_BLOCK]);
+
+		if (!block_index) {
+			NL_SET_ERR_MSG(extack, "Ingress block index cannot be 0");
+			return -EINVAL;
+		}
+		if (!sch->ops->ingress_block_set) {
+			NL_SET_ERR_MSG(extack, "Ingress block sharing is not supported");
+			return -EOPNOTSUPP;
+		}
+		sch->ops->ingress_block_set(sch, block_index);
+	}
+	if (tca[TCA_EGRESS_BLOCK]) {
+		block_index = nla_get_u32(tca[TCA_EGRESS_BLOCK]);
+
+		if (!block_index) {
+			NL_SET_ERR_MSG(extack, "Egress block index cannot be 0");
+			return -EINVAL;
+		}
+		if (!sch->ops->egress_block_set) {
+			NL_SET_ERR_MSG(extack, "Egress block sharing is not supported");
+			return -EOPNOTSUPP;
+		}
+		sch->ops->egress_block_set(sch, block_index);
+	}
+	return 0;
+}
+
 /* lockdep annotation is needed for ingress; egress gets it only for name */
 static struct lock_class_key qdisc_tx_lock;
 static struct lock_class_key qdisc_rx_lock;
···
 		netdev_info(dev, "Caught tx_queue_len zero misconfig\n");
 	}
 
+	err = qdisc_block_indexes_set(sch, tca, extack);
+	if (err)
+		goto err_out3;
+
 	if (ops->init) {
 		err = ops->init(sch, tca[TCA_OPTIONS], extack);
 		if (err != 0)
···
 		if (!sch->ops->change) {
 			NL_SET_ERR_MSG(extack, "Change operation not supported by specified qdisc");
 			return -EINVAL;
+		}
+		if (tca[TCA_INGRESS_BLOCK] || tca[TCA_EGRESS_BLOCK]) {
+			NL_SET_ERR_MSG(extack, "Change of blocks is not supported");
+			return -EOPNOTSUPP;
 		}
 		err = sch->ops->change(sch, tca[TCA_OPTIONS], extack);
 		if (err)
···
 			err = -EINVAL;
 			goto out;
 		}
+	}
+
+	if (tca[TCA_INGRESS_BLOCK] || tca[TCA_EGRESS_BLOCK]) {
+		NL_SET_ERR_MSG(extack, "Shared blocks are not supported for classes");
+		return -EOPNOTSUPP;
 	}
 
 	new_cl = cl;