Revert "vti4: Don't override MTU passed on link creation via IFLA_MTU"

This reverts commit d82309e24315a99a29342d330f6142122e249963 which is
03080e5ec727 ("vti4: Don't override MTU passed on link creation via
IFLA_MTU") upstream as it causes test failures.

This commit should not have been backported to anything older than 4.16,
despite what the changelog said as the mtu must be set in older kernels,
unlike is needed in 4.16 and newer.

Thanks to Alistair Strachan for the debugging help figuring this out,
and for 'git bisect' for making my life a whole lot easier.

Cc: Alistair Strachan <astrachan@google.com>
Cc: Stefano Brivio <sbrivio@redhat.com>
Cc: Sabrina Dubroca <sd@queasysnail.net>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 1ac55b116d5a1f4aa676cd5dfdfa761cbf7dcf76..cbff0d6ff1ac826a007af8d727d19856506c921d 100644 (file)
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -396,6 +396,7 @@ static int vti_tunnel_init(struct net_device *dev)
        memcpy(dev->dev_addr, &iph->saddr, 4);
        memcpy(dev->broadcast, &iph->daddr, 4);
 
+       dev->mtu                = ETH_DATA_LEN;
        dev->flags              = IFF_NOARP;
        dev->addr_len           = 4;
        dev->features           |= NETIF_F_LLTX;