queue-5.1/neighbor-call-__ipv4_neigh_lookup_noref-in-neigh_xmit.patch

   1 From foo@baz Sun 09 Jun 2019 09:24:16 AM CEST
   2 From: David Ahern <dsahern@gmail.com>
   3 Date: Wed, 1 May 2019 18:18:42 -0700
   4 Subject: neighbor: Call __ipv4_neigh_lookup_noref in neigh_xmit
   5
   6 From: David Ahern <dsahern@gmail.com>
   7
   8 [ Upstream commit 4b2a2bfeb3f056461a90bd621e8bd7d03fa47f60 ]
   9
  10 Commit cd9ff4de0107 changed the key for IFF_POINTOPOINT devices to
  11 INADDR_ANY but neigh_xmit which is used for MPLS encapsulations was not
  12 updated to use the altered key. The result is that every packet Tx does
  13 a lookup on the gateway address which does not find an entry, a new one
  14 is created only to find the existing one in the table right before the
  15 insert since arp_constructor was updated to reset the primary key. This
  16 is seen in the allocs and destroys counters:
  17     ip -s -4 ntable show | head -10 | grep alloc
  18
  19 which increase for each packet showing the unnecessary overhread.
  20
  21 Fix by having neigh_xmit use __ipv4_neigh_lookup_noref for NEIGH_ARP_TABLE.
  22
  23 Fixes: cd9ff4de0107 ("ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY")
  24 Reported-by: Alan Maguire <alan.maguire@oracle.com>
  25 Signed-off-by: David Ahern <dsahern@gmail.com>
  26 Tested-by: Alan Maguire <alan.maguire@oracle.com>
  27 Signed-off-by: David S. Miller <davem@davemloft.net>
  28 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29 ---
  30  net/core/neighbour.c |    9 ++++++++-
  31  1 file changed, 8 insertions(+), 1 deletion(-)
  32
  33 --- a/net/core/neighbour.c
  34 +++ b/net/core/neighbour.c
  35 @@ -31,6 +31,7 @@
  36  #include <linux/times.h>
  37  #include <net/net_namespace.h>
  38  #include <net/neighbour.h>
  39 +#include <net/arp.h>
  40  #include <net/dst.h>
  41  #include <net/sock.h>
  42  #include <net/netevent.h>
  43 @@ -2984,7 +2985,13 @@ int neigh_xmit(int index, struct net_dev
  44                 if (!tbl)
  45                         goto out;
  46                 rcu_read_lock_bh();
  47 -               neigh = __neigh_lookup_noref(tbl, addr, dev);
  48 +               if (index == NEIGH_ARP_TABLE) {
  49 +                       u32 key = *((u32 *)addr);
  50 +
  51 +                       neigh = __ipv4_neigh_lookup_noref(dev, key);
  52 +               } else {
  53 +                       neigh = __neigh_lookup_noref(tbl, addr, dev);
  54 +               }
  55                 if (!neigh)
  56                         neigh = __neigh_create(tbl, addr, dev, false);
  57                 err = PTR_ERR(neigh);