Commit 169fd627 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Paolo Abeni
Browse files

ipv6: Get rid of RTNL for SIOCADDRT and RTM_NEWROUTE. 



Now we are ready to remove RTNL from SIOCADDRT and RTM_NEWROUTE.

The remaining things to do are

  1. pass false to lwtunnel_valid_encap_type_attr()
  2. use rcu_dereference_rtnl() in fib6_check_nexthop()
  3. place rcu_read_lock() before ip6_route_info_create_nh().

Let's complete the RTNL-free conversion.

When each CPU-X adds 100000 routes on table-X in a batch
concurrently on c7a.metal-48xl EC2 instance with 192 CPUs,

without this series:

  $ sudo ./route_test.sh
  ...
  added 19200000 routes (100000 routes * 192 tables).
  time elapsed: 191577 milliseconds.

with this series:

  $ sudo ./route_test.sh
  ...
  added 19200000 routes (100000 routes * 192 tables).
  time elapsed: 62854 milliseconds.

I changed the number of routes in each table (1000 ~ 100000)
and consistently saw it finish 3x faster with this series.

Note that now every caller of lwtunnel_valid_encap_type() passes
false as the last argument, and this can be removed later.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250418000443.43734-16-kuniyu@amazon.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 081efd18

net/ipv4/nexthop.c

+2 −2
Original line number Diff line number Diff line
@@ -1556,12 +1556,12 @@ int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg, 
	if (nh->is_group) {

		struct nh_group *nhg;



		nhg = rtnl_dereference(nh->nh_grp);

		nhg = rcu_dereference_rtnl(nh->nh_grp);

		if (nhg->has_v4)

			goto no_v4_nh;

		is_fdb_nh = nhg->fdb_nh;

	} else {

		nhi = rtnl_dereference(nh->nh_info);

		nhi = rcu_dereference_rtnl(nh->nh_info);

		if (nhi->family == AF_INET)

			goto no_v4_nh;

		is_fdb_nh = nhi->fdb_nh;

net/ipv6/route.c

+12 −6
Original line number Diff line number Diff line
@@ -3903,12 +3903,16 @@ int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags, 
	if (IS_ERR(rt))

		return PTR_ERR(rt);



	rcu_read_lock();



	err = ip6_route_info_create_nh(rt, cfg, extack);

	if (err)

		return err;

		goto unlock;



	err = __ip6_ins_rt(rt, &cfg->fc_nlinfo, extack);

	fib6_info_release(rt);

unlock:

	rcu_read_unlock();



	return err;

}
@@ -4529,12 +4533,10 @@ int ipv6_route_ioctl(struct net *net, unsigned int cmd, struct in6_rtmsg *rtmsg) 


	switch (cmd) {

	case SIOCADDRT:

		rtnl_lock();

		/* Only do the default setting of fc_metric in route adding */

		if (cfg.fc_metric == 0)

			cfg.fc_metric = IP6_RT_PRIO_USER;

		err = ip6_route_add(&cfg, GFP_KERNEL, NULL);

		rtnl_unlock();

		break;

	case SIOCDELRT:

		err = ip6_route_del(&cfg, NULL);
@@ -5113,7 +5115,7 @@ static int rtm_to_fib6_multipath_config(struct fib6_config *cfg, 
	} while (rtnh_ok(rtnh, remaining));



	return lwtunnel_valid_encap_type_attr(cfg->fc_mp, cfg->fc_mp_len,

					      extack, newroute);

					      extack, false);

}



static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -5251,7 +5253,7 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh, 
		cfg->fc_encap_type = nla_get_u16(tb[RTA_ENCAP_TYPE]);



		err = lwtunnel_valid_encap_type(cfg->fc_encap_type,

						extack, newroute);

						extack, false);

		if (err < 0)

			goto errout;

	}
@@ -5518,6 +5520,8 @@ static int ip6_route_multipath_add(struct fib6_config *cfg, 
	if (err)

		return err;



	rcu_read_lock();



	err = ip6_route_mpath_info_create_nh(&rt6_nh_list, extack);

	if (err)

		goto cleanup;
@@ -5609,6 +5613,8 @@ static int ip6_route_multipath_add(struct fib6_config *cfg, 
	}



cleanup:

	rcu_read_unlock();



	list_for_each_entry_safe(nh, nh_safe, &rt6_nh_list, list) {

		fib6_info_release(nh->fib6_info);

		list_del(&nh->list);
@@ -6891,7 +6897,7 @@ static void bpf_iter_unregister(void) 


static const struct rtnl_msg_handler ip6_route_rtnl_msg_handlers[] __initconst_or_module = {

	{.owner = THIS_MODULE, .protocol = PF_INET6, .msgtype = RTM_NEWROUTE,

	 .doit = inet6_rtm_newroute},

	 .doit = inet6_rtm_newroute, .flags = RTNL_FLAG_DOIT_UNLOCKED},

	{.owner = THIS_MODULE, .protocol = PF_INET6, .msgtype = RTM_DELROUTE,

	 .doit = inet6_rtm_delroute, .flags = RTNL_FLAG_DOIT_UNLOCKED},

	{.owner = THIS_MODULE, .protocol = PF_INET6, .msgtype = RTM_GETROUTE,