From 45e4fd26683c9a5f88600d91b08a484f7f09226a Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 22 May 2015 20:56:00 -0700 Subject: ipv6: Only create RTF_CACHE routes after encountering pmtu exception This patch creates a RTF_CACHE routes only after encountering a pmtu exception. After ip6_rt_update_pmtu() has inserted the RTF_CACHE route to the fib6 tree, the rt->rt6i_node->fn_sernum is bumped which will fail the ip6_dst_check() and trigger a relookup. Signed-off-by: Martin KaFai Lau Cc: Hannes Frederic Sowa Cc: Steffen Klassert Cc: Julian Anastasov Signed-off-by: David S. Miller --- net/ipv6/route.c | 100 ++++++++++++++++++++++++++++--------------------------- 1 file changed, 51 insertions(+), 49 deletions(-) (limited to 'net/ipv6/route.c') diff --git a/net/ipv6/route.c b/net/ipv6/route.c index f199d6357b31..e7ae2430dfed 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -873,16 +873,13 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table, struct flowi6 *fl6, int flags) { struct fib6_node *fn, *saved_fn; - struct rt6_info *rt, *nrt; + struct rt6_info *rt; int strict = 0; - int attempts = 3; - int err; strict |= flags & RT6_LOOKUP_F_IFACE; if (net->ipv6.devconf_all->forwarding == 0) strict |= RT6_LOOKUP_F_REACHABLE; -redo_fib6_lookup_lock: read_lock_bh(&table->tb6_lock); fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr); @@ -901,46 +898,12 @@ redo_rt6_select: strict &= ~RT6_LOOKUP_F_REACHABLE; fn = saved_fn; goto redo_rt6_select; - } else { - dst_hold(&rt->dst); - read_unlock_bh(&table->tb6_lock); - goto out2; } } dst_hold(&rt->dst); read_unlock_bh(&table->tb6_lock); - if (rt->rt6i_flags & RTF_CACHE) - goto out2; - - if (!rt6_is_gw_or_nonexthop(rt) || - !(rt->dst.flags & DST_HOST) || !(rt->rt6i_flags & RTF_LOCAL)) - nrt = ip6_rt_cache_alloc(rt, &fl6->daddr, &fl6->saddr); - else - goto out2; - - ip6_rt_put(rt); - rt = nrt ? : net->ipv6.ip6_null_entry; - - dst_hold(&rt->dst); - if (nrt) { - err = ip6_ins_rt(nrt); - if (!err) - goto out2; - } - - if (--attempts <= 0) - goto out2; - - /* - * Race condition! In the gap, when table->tb6_lock was - * released someone could insert this route. Relookup. - */ - ip6_rt_put(rt); - goto redo_fib6_lookup_lock; - -out2: rt6_dst_from_metrics_check(rt); rt->dst.lastuse = jiffies; rt->dst.__use++; @@ -1113,24 +1076,63 @@ static void ip6_link_failure(struct sk_buff *skb) } } -static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, - struct sk_buff *skb, u32 mtu) +static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu) +{ + struct net *net = dev_net(rt->dst.dev); + + rt->rt6i_flags |= RTF_MODIFIED; + rt->rt6i_pmtu = mtu; + rt6_update_expires(rt, net->ipv6.sysctl.ip6_rt_mtu_expires); +} + +static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk, + const struct ipv6hdr *iph, u32 mtu) { struct rt6_info *rt6 = (struct rt6_info *)dst; - dst_confirm(dst); - if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) { - struct net *net = dev_net(dst->dev); + if (rt6->rt6i_flags & RTF_LOCAL) + return; - rt6->rt6i_flags |= RTF_MODIFIED; - if (mtu < IPV6_MIN_MTU) - mtu = IPV6_MIN_MTU; + dst_confirm(dst); + mtu = max_t(u32, mtu, IPV6_MIN_MTU); + if (mtu >= dst_mtu(dst)) + return; - rt6->rt6i_pmtu = mtu; - rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires); + if (rt6->rt6i_flags & RTF_CACHE) { + rt6_do_update_pmtu(rt6, mtu); + } else { + const struct in6_addr *daddr, *saddr; + struct rt6_info *nrt6; + + if (iph) { + daddr = &iph->daddr; + saddr = &iph->saddr; + } else if (sk) { + daddr = &sk->sk_v6_daddr; + saddr = &inet6_sk(sk)->saddr; + } else { + return; + } + nrt6 = ip6_rt_cache_alloc(rt6, daddr, saddr); + if (nrt6) { + rt6_do_update_pmtu(nrt6, mtu); + + /* ip6_ins_rt(nrt6) will bump the + * rt6->rt6i_node->fn_sernum + * which will fail the next rt6_check() and + * invalidate the sk->sk_dst_cache. + */ + ip6_ins_rt(nrt6); + } } } +static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, + struct sk_buff *skb, u32 mtu) +{ + __ip6_rt_update_pmtu(dst, sk, skb ? ipv6_hdr(skb) : NULL, mtu); +} + void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu, int oif, u32 mark) { @@ -1147,7 +1149,7 @@ void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu, dst = ip6_route_output(net, NULL, &fl6); if (!dst->error) - ip6_rt_update_pmtu(dst, NULL, skb, ntohl(mtu)); + __ip6_rt_update_pmtu(dst, NULL, iph, ntohl(mtu)); dst_release(dst); } EXPORT_SYMBOL_GPL(ip6_update_pmtu); -- cgit v1.2.3