net: Abstract default ADVMSS behind an accessor.
Make all RTAX_ADVMSS metric accesses go through a new helper function,
dst_metric_advmss().
Leave the actual default metric as "zero" in the real metric slot,
and compute the actual default value dynamically via a new dst_ops
AF specific callback.
For stacked IPSEC routes, we use the advmss of the path which
preserves existing behavior.
Unlike ipv4/ipv6, DecNET ties the advmss to the mtu and thus updates
advmss on pmtu updates. This inconsistency in advmss handling
results in more raw metric accesses than I wish we ended up with.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index fee0768..20aa95e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1521,7 +1521,7 @@
tcp_mtup_init(newsk);
tcp_sync_mss(newsk, dst_mtu(dst));
- newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
+ newtp->advmss = dst_metric_advmss(dst);
tcp_initialize_rcv_mss(newsk);
newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;