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Diffstat (limited to 'include/net/ip.h')
-rw-r--r--include/net/ip.h22
1 files changed, 18 insertions, 4 deletions
diff --git a/include/net/ip.h b/include/net/ip.h
index d9683bef8684..9192444f2964 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -436,18 +436,32 @@ static inline bool ip_sk_ignore_df(const struct sock *sk)
static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
bool forwarding)
{
+ const struct rtable *rt = container_of(dst, struct rtable, dst);
struct net *net = dev_net(dst->dev);
unsigned int mtu;
if (net->ipv4.sysctl_ip_fwd_use_pmtu ||
ip_mtu_locked(dst) ||
- !forwarding)
- return dst_mtu(dst);
+ !forwarding) {
+ mtu = rt->rt_pmtu;
+ if (mtu && time_before(jiffies, rt->dst.expires))
+ goto out;
+ }
/* 'forwarding = true' case should always honour route mtu */
mtu = dst_metric_raw(dst, RTAX_MTU);
- if (!mtu)
- mtu = min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU);
+ if (mtu)
+ goto out;
+
+ mtu = READ_ONCE(dst->dev->mtu);
+
+ if (unlikely(ip_mtu_locked(dst))) {
+ if (rt->rt_uses_gateway && mtu > 576)
+ mtu = 576;
+ }
+
+out:
+ mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
}