tree 600acf57599f3906a88bc39adac0f461f0edbdf2
parent e70a3aad44cc8b24986687ffc98c4a4f6ecf25ea
author Xin Long <lucien.xin@gmail.com> 1533480367 +0800
committer David S. Miller <davem@davemloft.net> 1533515702 -0700

ip6_tunnel: use the right value for ipv4 min mtu check in ip6_tnl_xmit

According to RFC791, 68 bytes is the minimum size of IPv4 datagram every
device must be able to forward without further fragmentation while 576
bytes is the minimum size of IPv4 datagram every device has to be able
to receive, so in ip6_tnl_xmit(), 68(IPV4_MIN_MTU) should be the right
value for the ipv4 min mtu check in ip6_tnl_xmit.

While at it, change to use max() instead of if statement.

Fixes: c9fefa08190f ("ip6_tunnel: get the min mtu properly in ip6_tnl_xmit")
Reported-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>