• Maciej Żenczykowski's avatar
    Revert "ipv6: add mtu lock check in __ip6_rt_update_pmtu" · 09454fd0
    Maciej Żenczykowski authored
    This reverts commit 19bda36c:
    
    | ipv6: add mtu lock check in __ip6_rt_update_pmtu
    |
    | Prior to this patch, ipv6 didn't do mtu lock check in ip6_update_pmtu.
    | It leaded to that mtu lock doesn't really work when receiving the pkt
    | of ICMPV6_PKT_TOOBIG.
    |
    | This patch is to add mtu lock check in __ip6_rt_update_pmtu just as ipv4
    | did in __ip_rt_update_pmtu.
    
    The above reasoning is incorrect.  IPv6 *requires* icmp based pmtu to work.
    There's already a comment to this effect elsewhere in the kernel:
    
      $ git grep -p -B1 -A3 'RTAX_MTU lock'
      net/ipv6/route.c=4813=
    
      static int rt6_mtu_change_route(struct fib6_info *f6i, void *p_arg)
      ...
        /* In IPv6 pmtu discovery is not optional,
           so that RTAX_MTU lock cannot disable it.
           We still use this lock to block changes
           caused by addrconf/ndisc.
        */
    
    This reverts to the pre-4.9 behaviour.
    
    Cc: Eric Dumazet <edumazet@google.com>
    Cc: Willem de Bruijn <willemb@google.com>
    Cc: Xin Long <lucien.xin@gmail.com>
    Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
    Signed-off-by: default avatarMaciej Żenczykowski <maze@google.com>
    Fixes: 19bda36c ("ipv6: add mtu lock check in __ip6_rt_update_pmtu")
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    09454fd0
route.c 159 KB