Commit 0e041220 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'net-speedup-some-nexthop-handling-when-having-a-lot-of-nexthops' 

Christoph Paasch says:

====================
net: Speedup some nexthop handling when having A LOT of nexthops

Configuring a very large number of nexthops is fairly possible within
a reasonable time-frame. But, certain netlink commands can become
extremely slow.

This series addresses some of these, namely dumping and removing
nexthops.

v1: https://lore.kernel.org/20250724-nexthop_dump-v1-1-6b43fffd5bac@openai.com
====================

Link: https://patch.msgid.link/20250816-nexthop_dump-v2-0-491da3462118@openai.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 51992f99 b0ac6d3b

net/ipv4/nexthop.c

+39 −3
Original line number Diff line number Diff line
@@ -2087,6 +2087,12 @@ static void remove_nexthop_from_groups(struct net *net, struct nexthop *nh, 
{

	struct nh_grp_entry *nhge, *tmp;



	/* If there is nothing to do, let's avoid the costly call to

	 * synchronize_net()

	 */

	if (list_empty(&nh->grp_list))

		return;



	list_for_each_entry_safe(nhge, tmp, &nh->grp_list, nh_list)

		remove_nh_grp_entry(net, nhge, nlinfo);
@@ -3511,12 +3517,42 @@ static int rtm_dump_walk_nexthops(struct sk_buff *skb, 
	int err;



	s_idx = ctx->idx;

	for (node = rb_first(root); node; node = rb_next(node)) {



	/* If this is not the first invocation, ctx->idx will contain the id of

	 * the last nexthop we processed. Instead of starting from the very

	 * first element of the red/black tree again and linearly skipping the

	 * (potentially large) set of nodes with an id smaller than s_idx, walk

	 * the tree and find the left-most node whose id is >= s_idx.  This

	 * provides an efficient O(log n) starting point for the dump

	 * continuation.

	 */

	if (s_idx != 0) {

		struct rb_node *tmp = root->rb_node;



		node = NULL;

		while (tmp) {

			struct nexthop *nh;



			nh = rb_entry(tmp, struct nexthop, rb_node);

			if (nh->id < s_idx) {

				tmp = tmp->rb_right;

			} else {

				/* Track current candidate and keep looking on

				 * the left side to find the left-most

				 * (smallest id) that is still >= s_idx.

				 */

				node = tmp;

				tmp = tmp->rb_left;

			}

		}

	} else {

		node = rb_first(root);

	}



	for (; node; node = rb_next(node)) {

		struct nexthop *nh;



		nh = rb_entry(node, struct nexthop, rb_node);

		if (nh->id < s_idx)

			continue;



		ctx->idx = nh->id;

		err = nh_cb(skb, cb, nh, data);