[PATCH RFC v2 net-next 09/21] net/ipv6: Defer initialization of dst to data path

From: David Ahern <hidden>
Date: 2018-03-19 03:37:45
Subsystem: networking [general], networking [ipv4/ipv6], the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds

Defer setting dst input, output and error until fib entry is copied.

The reject path from ip6_route_info_create is moved to a new function
ip6_rt_init_dst_reject with a helper doing the conversion from fib6_type
to dst error.

The remainder of the new ip6_rt_init_dst is an amalgamtion of dst code
from addrconf_dst_alloc and the non-reject path of ip6_route_info_create.
The dst output function is always ip6_output and the input function is
either ip6_input (local routes), ip6_mc_input (multicast routes) or
ip6_forward (anything else).

A couple of places using dst.error are updated to look at rt6i_flags.

Signed-off-by: David Ahern <redacted>
---
 net/ipv6/route.c | 115 +++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 74 insertions(+), 41 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 43e1ab7cdf4f..adff60c07ae9 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c

@@ -920,6 +920,75 @@ static struct net_device *ip6_rt_get_dev_rcu(struct rt6_info *rt)
 	return dev;
 }
 
+static const int fib6_prop[RTN_MAX + 1] = {
+	[RTN_UNSPEC]	= 0,
+	[RTN_UNICAST]	= 0,
+	[RTN_LOCAL]	= 0,
+	[RTN_BROADCAST]	= 0,
+	[RTN_ANYCAST]	= 0,
+	[RTN_MULTICAST]	= 0,
+	[RTN_BLACKHOLE]	= -EINVAL,
+	[RTN_UNREACHABLE] = -EHOSTUNREACH,
+	[RTN_PROHIBIT]	= -EACCES,
+	[RTN_THROW]	= -EAGAIN,
+	[RTN_NAT]	= -EINVAL,
+	[RTN_XRESOLVE]	= -EINVAL,
+};
+
+static int ip6_rt_type_to_error(u8 fib6_type)
+{
+	return fib6_prop[fib6_type];
+}
+
+static void ip6_rt_init_dst_reject(struct rt6_info *rt, struct rt6_info *ort)
+{
+	rt->dst.error = ip6_rt_type_to_error(ort->fib6_type);
+
+	switch (ort->fib6_type) {
+	case RTN_BLACKHOLE:
+		rt->dst.output = dst_discard_out;
+		rt->dst.input = dst_discard;
+		break;
+	case RTN_PROHIBIT:
+		rt->dst.output = ip6_pkt_prohibit_out;
+		rt->dst.input = ip6_pkt_prohibit;
+		break;
+	case RTN_THROW:
+	case RTN_UNREACHABLE:
+	default:
+		rt->dst.output = ip6_pkt_discard_out;
+		rt->dst.input = ip6_pkt_discard;
+		break;
+	}
+}
+
+static void ip6_rt_init_dst(struct rt6_info *rt, struct rt6_info *ort)
+{
+	if (ort->rt6i_flags & RTF_REJECT) {
+		ip6_rt_init_dst_reject(rt, ort);
+		return;
+	}
+
+	rt->dst.error = 0;
+	rt->dst.output = ip6_output;
+
+	if (ort->fib6_type == RTN_LOCAL) {
+		rt->dst.flags |= DST_HOST;
+		rt->dst.input = ip6_input;
+	} else if (ipv6_addr_type(&ort->rt6i_dst.addr) & IPV6_ADDR_MULTICAST) {
+		rt->dst.input = ip6_mc_input;
+	} else {
+		rt->dst.input = ip6_forward;
+	}
+
+	if (ort->fib6_nh.nh_lwtstate) {
+		rt->dst.lwtstate = lwtstate_get(ort->fib6_nh.nh_lwtstate);
+		lwtunnel_set_redirect(&rt->dst);
+	}
+
+	rt->dst.lastuse = jiffies;
+}
+
 static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
 {
 	BUG_ON(from->from);

@@ -932,14 +1001,12 @@ static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
 
 static void ip6_rt_copy_init(struct rt6_info *rt, struct rt6_info *ort)
 {
-	rt->dst.input = ort->dst.input;
-	rt->dst.output = ort->dst.output;
+	ip6_rt_init_dst(rt, ort);
+
 	rt->rt6i_dst = ort->rt6i_dst;
-	rt->dst.error = ort->dst.error;
 	rt->rt6i_idev = ort->rt6i_idev;
 	if (rt->rt6i_idev)
 		in6_dev_hold(rt->rt6i_idev);
-	rt->dst.lastuse = jiffies;
 	rt->rt6i_gateway = ort->fib6_nh.nh_gw;
 	rt->rt6i_flags = ort->rt6i_flags;
 	rt6_set_from(rt, ort);

@@ -2283,7 +2350,7 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
 			continue;
 		if (rt6_check_expired(rt))
 			continue;
-		if (rt->dst.error)
+		if (rt->rt6i_flags & RTF_REJECT)
 			break;
 		if (!(rt->rt6i_flags & RTF_GATEWAY))
 			continue;

@@ -2311,7 +2378,7 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
 
 	if (!rt)
 		rt = net->ipv6.ip6_null_entry;
-	else if (rt->dst.error) {
+	else if (rt->rt6i_flags & RTF_REJECT) {
 		rt = net->ipv6.ip6_null_entry;
 		goto out;
 	}

@@ -2854,15 +2921,6 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg,
 
 	addr_type = ipv6_addr_type(&cfg->fc_dst);
 
-	if (addr_type & IPV6_ADDR_MULTICAST)
-		rt->dst.input = ip6_mc_input;
-	else if (cfg->fc_flags & RTF_LOCAL)
-		rt->dst.input = ip6_input;
-	else
-		rt->dst.input = ip6_forward;
-
-	rt->dst.output = ip6_output;
-
 	if (cfg->fc_encap) {
 		struct lwtunnel_state *lwtstate;

@@ -2872,7 +2930,6 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg,
 		if (err)
 			goto out;
 		rt->fib6_nh.nh_lwtstate = lwtstate_get(lwtstate);
-		lwtunnel_set_redirect(&rt->dst);
 	}
 
 	ipv6_addr_prefix(&rt->rt6i_dst.addr, &cfg->fc_dst, cfg->fc_dst_len);

@@ -2912,27 +2969,6 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg,
 			}
 		}
 		rt->rt6i_flags = RTF_REJECT|RTF_NONEXTHOP;
-		switch (cfg->fc_type) {
-		case RTN_BLACKHOLE:
-			rt->dst.error = -EINVAL;
-			rt->dst.output = dst_discard_out;
-			rt->dst.input = dst_discard;
-			break;
-		case RTN_PROHIBIT:
-			rt->dst.error = -EACCES;
-			rt->dst.output = ip6_pkt_prohibit_out;
-			rt->dst.input = ip6_pkt_prohibit;
-			break;
-		case RTN_THROW:
-		case RTN_UNREACHABLE:
-		default:
-			rt->dst.error = (cfg->fc_type == RTN_THROW) ? -EAGAIN
-					: (cfg->fc_type == RTN_UNREACHABLE)
-					? -EHOSTUNREACH : -ENETUNREACH;
-			rt->dst.output = ip6_pkt_discard_out;
-			rt->dst.input = ip6_pkt_discard;
-			break;
-		}
 		goto install_route;
 	}

@@ -3570,12 +3606,9 @@ struct rt6_info *addrconf_dst_alloc(struct net *net,
 		return ERR_PTR(-ENOMEM);
 
 	in6_dev_hold(idev);
-
-	rt->dst.flags |= DST_HOST;
-	rt->dst.input = ip6_input;
-	rt->dst.output = ip6_output;
 	rt->rt6i_idev = idev;
 
+	rt->dst.flags |= DST_HOST;
 	rt->rt6i_protocol = RTPROT_KERNEL;
 	rt->rt6i_flags = RTF_UP | RTF_NONEXTHOP;
 	if (anycast) {

-- 
2.11.0

`h`	back out one level
`j`	next message in thread
`k`	previous message in thread
`l`	drill in
`Esc`	close help / fold thread tree
`?`	toggle this help