Commit 77d5bc7e authored by David Ahern's avatar David Ahern Committed by Jakub Kicinski
Browse files

ipv4: Revert removal of rt_uses_gateway 

Julian noted that rt_uses_gateway has a more subtle use than 'is gateway
set':
    https://lore.kernel.org/netdev/alpine.LFD.2.21.1909151104060.2546@ja.home.ssi.bg/



Revert that part of the commit referenced in the Fixes tag.

Currently, there are no u8 holes in 'struct rtable'. There is a 4-byte hole
in the second cacheline which contains the gateway declaration. So move
rt_gw_family down to the gateway declarations since they are always used
together, and then re-use that u8 for rt_uses_gateway. End result is that
rtable size is unchanged.

Fixes: 1550c171 ("ipv4: Prepare rtable for IPv6 gateway")
Reported-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Reviewed-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
parent e84622ce

drivers/infiniband/core/addr.c

+1 −1
Original line number Diff line number Diff line
@@ -352,7 +352,7 @@ static bool has_gateway(const struct dst_entry *dst, sa_family_t family) 


	if (family == AF_INET) {

		rt = container_of(dst, struct rtable, dst);

		return rt->rt_gw_family == AF_INET;

		return rt->rt_uses_gateway;

	}



	rt6 = container_of(dst, struct rt6_info, dst);

include/net/route.h

+2 −1
Original line number Diff line number Diff line
@@ -53,10 +53,11 @@ struct rtable { 
	unsigned int		rt_flags;

	__u16			rt_type;

	__u8			rt_is_input;

	u8			rt_gw_family;

	__u8			rt_uses_gateway;



	int			rt_iif;



	u8			rt_gw_family;

	/* Info on neighbour */

	union {

		__be32		rt_gw4;

net/ipv4/inet_connection_sock.c

+2 −2
Original line number Diff line number Diff line
@@ -560,7 +560,7 @@ struct dst_entry *inet_csk_route_req(const struct sock *sk, 
	rt = ip_route_output_flow(net, fl4, sk);

	if (IS_ERR(rt))

		goto no_route;

	if (opt && opt->opt.is_strictroute && rt->rt_gw_family)

	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)

		goto route_err;

	rcu_read_unlock();

	return &rt->dst;
@@ -598,7 +598,7 @@ struct dst_entry *inet_csk_route_child_sock(const struct sock *sk, 
	rt = ip_route_output_flow(net, fl4, sk);

	if (IS_ERR(rt))

		goto no_route;

	if (opt && opt->opt.is_strictroute && rt->rt_gw_family)

	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)

		goto route_err;

	return &rt->dst;

net/ipv4/ip_forward.c

+1 −1
Original line number Diff line number Diff line
@@ -123,7 +123,7 @@ int ip_forward(struct sk_buff *skb) 


	rt = skb_rtable(skb);



	if (opt->is_strictroute && rt->rt_gw_family)

	if (opt->is_strictroute && rt->rt_uses_gateway)

		goto sr_failed;



	IPCB(skb)->flags |= IPSKB_FORWARDED;

net/ipv4/ip_output.c

+1 −1
Original line number Diff line number Diff line
@@ -499,7 +499,7 @@ int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl, 
	skb_dst_set_noref(skb, &rt->dst);



packet_routed:

	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_gw_family)

	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)

		goto no_route;



	/* OK, we know where to send it, allocate and build IP header. */

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