releases/4.14.7/s390-qeth-fix-thinko-in-ipv4-multicast-address-tracking.patch

   1 From foo@baz Thu Dec 14 11:45:40 CET 2017
   2 From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
   3 Date: Fri, 1 Dec 2017 10:14:49 +0100
   4 Subject: s390/qeth: fix thinko in IPv4 multicast address tracking
   5
   6 From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
   7
   8
   9 [ Upsteam commit bc3ab70584696cb798b9e1e0ac8e6ced5fd4c3b8 ]
  10
  11 Commit 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback")
  12 reworked how secondary addresses are managed for qeth devices.
  13 Instead of dropping & subsequently re-adding all addresses on every
  14 ndo_set_rx_mode() call, qeth now keeps track of the addresses that are
  15 currently registered with the HW.
  16 On a ndo_set_rx_mode(), we thus only need to do (de-)registration
  17 requests for the addresses that have actually changed.
  18
  19 On L3 devices, the lookup for IPv4 Multicast addresses checks the wrong
  20 hashtable - and thus never finds a match. As a result, we first delete
  21 *all* such addresses, and then re-add them again. So each set_rx_mode()
  22 causes a short period where the IPv4 Multicast addresses are not
  23 registered, and the card stops forwarding inbound traffic for them.
  24
  25 Fix this by setting the ->is_multicast flag on the lookup object, thus
  26 enabling qeth_l3_ip_from_hash() to search the correct hashtable and
  27 find a match there.
  28
  29 Fixes: 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback")
  30 Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
  31 Signed-off-by: David S. Miller <davem@davemloft.net>
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  33 ---
  34  drivers/s390/net/qeth_l3_main.c |    1 +
  35  1 file changed, 1 insertion(+)
  36
  37 --- a/drivers/s390/net/qeth_l3_main.c
  38 +++ b/drivers/s390/net/qeth_l3_main.c
  39 @@ -1376,6 +1376,7 @@ qeth_l3_add_mc_to_hash(struct qeth_card
  40
  41                 tmp->u.a4.addr = be32_to_cpu(im4->multiaddr);
  42                 memcpy(tmp->mac, buf, sizeof(tmp->mac));
  43 +               tmp->is_multicast = 1;
  44
  45                 ipm = qeth_l3_ip_from_hash(card, tmp);
  46                 if (ipm) {