net: sched: cls_matchall: implement offload tcf_proto_op

Add the reoffload tcf_proto_op in matchall to generate an offload message
for each filter in the given tcf_proto. Call the specified callback with
this new offload message. The function only returns an error if the
callback rejects adding a 'hardware only' rule.

Ensure matchall flags correctly report if the rule is in hw by keeping a
reference counter for the number of instances of the rule offloaded. Only
update the flag when this counter changes from or to 0.
Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_matchall.c

@@ -21,6 +21,7 @@ struct cls_mall_head {
 	struct tcf_result res;
 	u32 handle;
 	u32 flags;
+	unsigned int in_hw_count;
 	struct rcu_work rwork;
 };
 
@@ -95,6 +96,7 @@ static int mall_replace_hw_filter(struct tcf_proto *tp,
 		mall_destroy_hw_filter(tp, head, cookie, NULL);
 		return err;
 	} else if (err > 0) {
+		head->in_hw_count = err;
 		tcf_block_offload_inc(block, &head->flags);
 	}
 
@@ -235,6 +237,35 @@ static void mall_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 	arg->count++;
 }
 
+static int mall_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
+			  void *cb_priv, struct netlink_ext_ack *extack)
+{
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+	struct tc_cls_matchall_offload cls_mall = {};
+	struct tcf_block *block = tp->chain->block;
+	int err;
+
+	if (tc_skip_hw(head->flags))
+		return 0;
+
+	tc_cls_common_offload_init(&cls_mall.common, tp, head->flags, extack);
+	cls_mall.command = add ?
+		TC_CLSMATCHALL_REPLACE : TC_CLSMATCHALL_DESTROY;
+	cls_mall.exts = &head->exts;
+	cls_mall.cookie = (unsigned long)head;
+
+	err = cb(TC_SETUP_CLSMATCHALL, &cls_mall, cb_priv);
+	if (err) {
+		if (add && tc_skip_sw(head->flags))
+			return err;
+		return 0;
+	}
+
+	tc_cls_offload_cnt_update(block, &head->in_hw_count, &head->flags, add);
+
+	return 0;
+}
+
 static int mall_dump(struct net *net, struct tcf_proto *tp, void *fh,
 		     struct sk_buff *skb, struct tcmsg *t)
 {
@@ -289,6 +320,7 @@ static struct tcf_proto_ops cls_mall_ops __read_mostly = {
 	.change		= mall_change,
 	.delete		= mall_delete,
 	.walk		= mall_walk,
+	.reoffload	= mall_reoffload,
 	.dump		= mall_dump,
 	.bind_class	= mall_bind_class,
 	.owner		= THIS_MODULE,