| Message ID | 1516297872-17552-1-git-send-email-alexey.kodanev@oracle.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net,v2] ip6_gre: init dev->mtu and dev->hard_header_len correctly | expand |
From: Alexey Kodanev <alexey.kodanev@oracle.com> Date: Thu, 18 Jan 2018 20:51:12 +0300 > Commit b05229f44228 ("gre6: Cleanup GREv6 transmit path, > call common GRE functions") moved dev->mtu initialization > from ip6gre_tunnel_setup() to ip6gre_tunnel_init(), as a > result, the previously set values, before ndo_init(), are > reset in the following cases: > > * rtnl_create_link() can update dev->mtu from IFLA_MTU > parameter. > > * ip6gre_tnl_link_config() is invoked before ndo_init() in > netlink and ioctl setup, so ndo_init() can reset MTU > adjustments with the lower device MTU as well, dev->mtu > and dev->hard_header_len. > > Not applicable for ip6gretap because it has one more call > to ip6gre_tnl_link_config(tunnel, 1) in ip6gre_tap_init(). > > Fix the first case by updating dev->mtu with 'tb[IFLA_MTU]' > parameter if a user sets it manually on a device creation, > and fix the second one by moving ip6gre_tnl_link_config() > call after register_netdevice(). > > Fixes: b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") > Fixes: db2ec95d1ba4 ("ip6_gre: Fix MTU setting") > Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com> > --- > > v2: Instead of checking whether dev->mtu equals zero or not > in ip6gre_tunnel_init_common(), update 'dev->mtu' once > more with 'IFLA_MTU' parameter after register_netdevice(). Applied and queued up for -stable, thanks Alexey. I was almost tricked that this approach would have problems because you do the MTU setting after register_netdevice(), but we hold the RTNL semaphore so even if the device becomes globally visible the user can't perform a change of the device's MTU before we do it. Thanks.
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 7726959..8735492 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -337,11 +337,12 @@ static void ip6gre_tunnel_unlink(struct ip6gre_net *ign, struct ip6_tnl *t) nt->dev = dev; nt->net = dev_net(dev); - ip6gre_tnl_link_config(nt, 1); if (register_netdevice(dev) < 0) goto failed_free; + ip6gre_tnl_link_config(nt, 1); + /* Can use a lockless transmit, unless we generate output sequences */ if (!(nt->parms.o_flags & TUNNEL_SEQ)) dev->features |= NETIF_F_LLTX; @@ -1303,7 +1304,6 @@ static void ip6gre_netlink_parms(struct nlattr *data[], static int ip6gre_tap_init(struct net_device *dev) { - struct ip6_tnl *tunnel; int ret; ret = ip6gre_tunnel_init_common(dev); @@ -1312,10 +1312,6 @@ static int ip6gre_tap_init(struct net_device *dev) dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; - tunnel = netdev_priv(dev); - - ip6gre_tnl_link_config(tunnel, 1); - return 0; } @@ -1408,12 +1404,16 @@ static int ip6gre_newlink(struct net *src_net, struct net_device *dev, nt->dev = dev; nt->net = dev_net(dev); - ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]); err = register_netdevice(dev); if (err) goto out; + ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]); + + if (tb[IFLA_MTU]) + ip6_tnl_change_mtu(dev, nla_get_u32(tb[IFLA_MTU])); + dev_hold(dev); ip6gre_tunnel_link(ign, nt);
Commit b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") moved dev->mtu initialization from ip6gre_tunnel_setup() to ip6gre_tunnel_init(), as a result, the previously set values, before ndo_init(), are reset in the following cases: * rtnl_create_link() can update dev->mtu from IFLA_MTU parameter. * ip6gre_tnl_link_config() is invoked before ndo_init() in netlink and ioctl setup, so ndo_init() can reset MTU adjustments with the lower device MTU as well, dev->mtu and dev->hard_header_len. Not applicable for ip6gretap because it has one more call to ip6gre_tnl_link_config(tunnel, 1) in ip6gre_tap_init(). Fix the first case by updating dev->mtu with 'tb[IFLA_MTU]' parameter if a user sets it manually on a device creation, and fix the second one by moving ip6gre_tnl_link_config() call after register_netdevice(). Fixes: b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") Fixes: db2ec95d1ba4 ("ip6_gre: Fix MTU setting") Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com> --- v2: Instead of checking whether dev->mtu equals zero or not in ip6gre_tunnel_init_common(), update 'dev->mtu' once more with 'IFLA_MTU' parameter after register_netdevice(). net/ipv6/ip6_gre.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-)