diff options
Diffstat (limited to 'net/ipv6/route.c')
| -rw-r--r-- | net/ipv6/route.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 038d661d5ffc..0a35ded448a6 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2604,6 +2604,54 @@ out: return mtu - lwtunnel_headroom(dst->lwtstate, mtu); } +/* MTU selection: + * 1. mtu on route is locked - use it + * 2. mtu from nexthop exception + * 3. mtu from egress device + * + * based on ip6_dst_mtu_forward and exception logic of + * rt6_find_cached_rt; called with rcu_read_lock + */ +u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr, + struct in6_addr *saddr) +{ + struct rt6_exception_bucket *bucket; + struct rt6_exception *rt6_ex; + struct in6_addr *src_key; + struct inet6_dev *idev; + u32 mtu = 0; + + if (unlikely(fib6_metric_locked(f6i, RTAX_MTU))) { + mtu = f6i->fib6_pmtu; + if (mtu) + goto out; + } + + src_key = NULL; +#ifdef CONFIG_IPV6_SUBTREES + if (f6i->fib6_src.plen) + src_key = saddr; +#endif + + bucket = rcu_dereference(f6i->rt6i_exception_bucket); + rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key); + if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i)) + mtu = dst_metric_raw(&rt6_ex->rt6i->dst, RTAX_MTU); + + if (likely(!mtu)) { + struct net_device *dev = fib6_info_nh_dev(f6i); + + mtu = IPV6_MIN_MTU; + idev = __in6_dev_get(dev); + if (idev && idev->cnf.mtu6 > mtu) + mtu = idev->cnf.mtu6; + } + + mtu = min_t(unsigned int, mtu, IP6_MAX_MTU); +out: + return mtu - lwtunnel_headroom(fib6_info_nh_lwt(f6i), mtu); +} + struct dst_entry *icmp6_dst_alloc(struct net_device *dev, struct flowi6 *fl6) { |