Commit 4f80116d authored by Roopa Prabhu's avatar Roopa Prabhu Committed by David S. Miller
Browse files

net: ipv4: add sysctl for nexthop api compatibility mode 



Current route nexthop API maintains user space compatibility
with old route API by default. Dumps and netlink notifications
support both new and old API format. In systems which have
moved to the new API, this compatibility mode cancels some
of the performance benefits provided by the new nexthop API.

This patch adds new sysctl nexthop_compat_mode which is on
by default but provides the ability to turn off compatibility
mode allowing systems to run entirely with the new routing
API. Old route API behaviour and support is not modified by this
sysctl.

Uses a single sysctl to cover both ipv4 and ipv6 following
other sysctls. Covers dumps and delete notifications as
suggested by David Ahern.

Signed-off-by: default avatarRoopa Prabhu <roopa@cumulusnetworks.com>
Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 11dd74b3

Documentation/networking/ip-sysctl.txt

+12 −0
Original line number Diff line number Diff line
@@ -1560,6 +1560,18 @@ skip_notify_on_dev_down - BOOLEAN 
	on userspace caches to track link events and evict routes.

	Default: false (generate message)



nexthop_compat_mode - BOOLEAN

	New nexthop API provides a means for managing nexthops independent of

	prefixes. Backwards compatibilty with old route format is enabled by

	default which means route dumps and notifications contain the new

	nexthop attribute but also the full, expanded nexthop definition.

	Further, updates or deletes of a nexthop configuration generate route

	notifications for each fib entry using the nexthop. Once a system

	understands the new API, this sysctl can be disabled to achieve full

	performance benefits of the new API by disabling the nexthop expansion

	and extraneous notifications.

	Default: true (backward compat mode)



IPv6 Fragmentation:



ip6frag_high_thresh - INTEGER

include/net/netns/ipv4.h

+2 −0
Original line number Diff line number Diff line
@@ -111,6 +111,8 @@ struct netns_ipv4 { 
	int sysctl_tcp_early_demux;

	int sysctl_udp_early_demux;



	int sysctl_nexthop_compat_mode;



	int sysctl_fwmark_reflect;

	int sysctl_tcp_fwmark_accept;

#ifdef CONFIG_NET_L3_MASTER_DEV

net/ipv4/af_inet.c

+1 −0
Original line number Diff line number Diff line
@@ -1835,6 +1835,7 @@ static __net_init int inet_init_net(struct net *net) 
	net->ipv4.sysctl_ip_early_demux = 1;

	net->ipv4.sysctl_udp_early_demux = 1;

	net->ipv4.sysctl_tcp_early_demux = 1;

	net->ipv4.sysctl_nexthop_compat_mode = 1;

#ifdef CONFIG_SYSCTL

	net->ipv4.sysctl_ip_prot_sock = PROT_SOCK;

#endif

net/ipv4/fib_semantics.c

+3 −0
Original line number Diff line number Diff line
@@ -1780,6 +1780,8 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event, 
			goto nla_put_failure;

		if (nexthop_is_blackhole(fi->nh))

			rtm->rtm_type = RTN_BLACKHOLE;

		if (!fi->fib_net->ipv4.sysctl_nexthop_compat_mode)

			goto offload;

	}



	if (nhs == 1) {
@@ -1805,6 +1807,7 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event, 
			goto nla_put_failure;

	}



offload:

	if (fri->offload)

		rtm->rtm_flags |= RTM_F_OFFLOAD;

	if (fri->trap)

net/ipv4/nexthop.c

+3 −2
Original line number Diff line number Diff line
@@ -784,7 +784,8 @@ static void __remove_nexthop_fib(struct net *net, struct nexthop *nh) 
	list_for_each_entry_safe(f6i, tmp, &nh->f6i_list, nh_list) {

		/* __ip6_del_rt does a release, so do a hold here */

		fib6_info_hold(f6i);

		ipv6_stub->ip6_del_rt(net, f6i, false);

		ipv6_stub->ip6_del_rt(net, f6i,

				      !net->ipv4.sysctl_nexthop_compat_mode);

	}

}
@@ -1041,7 +1042,7 @@ out: 
	if (!rc) {

		nh_base_seq_inc(net);

		nexthop_notify(RTM_NEWNEXTHOP, new_nh, &cfg->nlinfo);

		if (replace_notify)

		if (replace_notify && net->ipv4.sysctl_nexthop_compat_mode)

			nexthop_replace_notify(net, new_nh, &cfg->nlinfo);

	}

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