Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

Pull networking fixes from David Miller:
 "A quick batch of bug fixes:

  1) Fix build with IPV6 disabled, from Eric Dumazet.

  2) Several more cases of caching SKB data pointers across calls to
     pskb_may_pull(), thus referencing potentially free'd memory.  From
     Li RongQing.

  3) DSA phy code tests operation presence improperly, instead of going:

        if (x->ops->foo)
                r = x->ops->foo(args);

     it was going:

        if (x->ops->foo(args))
                r = x->ops->foo(args);

   Fix from Andew Lunn"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  Net: DSA: Fix checking for get_phy_flags function
  ipv6: fix a potential use after free in sit.c
  ipv6: fix a potential use after free in ip6_offload.c
  ipv4: fix a potential use after free in gre_offload.c
  tcp: fix build error if IPv6 is not enabled