[PATCH net-next 13/13] s390/qeth: improve fallback to random MAC address

[Julian Wiedmann]

From: Julian Wiedmann <j...@linux.vnet.ibm.com>

If READ MAC fails to fetch a valid MAC address, allow some more device
types (IQD and z/VM OSD) to fall back to a random address.
Also use eth_hw_addr_random(), for indicating to userspace that the
address type is NET_ADDR_RANDOM.

Note that while z/VM has various protection schemes to prohibit
custom addresses on its NICs, they are all optional. So we should at
least give it a try.

Signed-off-by: Julian Wiedmann <j...@linux.vnet.ibm.com>
---
 drivers/s390/net/qeth_l2_main.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 810d69bd9991..a7cb37da6a21 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -439,7 +439,6 @@ static int qeth_l2_process_inbound_buffer(struct qeth_card 
*card,
 static int qeth_l2_request_initial_mac(struct qeth_card *card)
 {
        int rc = 0;
-       char vendor_pre[] = {0x02, 0x00, 0x00};
 
        QETH_DBF_TEXT(SETUP, 2, "l2reqmac");
        QETH_DBF_TEXT_(SETUP, 2, "doL2%s", CARD_BUS_ID(card));
@@ -459,16 +458,20 @@ static int qeth_l2_request_initial_mac(struct qeth_card 
*card)
            card->info.type == QETH_CARD_TYPE_OSX ||
            card->info.guestlan) {
                rc = qeth_setadpparms_change_macaddr(card);
-               if (rc) {
-                       QETH_DBF_MESSAGE(2, "couldn't get MAC address on "
-                               "device %s: x%x\n", CARD_BUS_ID(card), rc);
-                       QETH_DBF_TEXT_(SETUP, 2, "1err%04x", rc);
-                       return rc;
-               }
-       } else {
-               eth_random_addr(card->dev->dev_addr);
-               memcpy(card->dev->dev_addr, vendor_pre, 3);
+               if (!rc)
+                       goto out;
+               QETH_DBF_MESSAGE(2, "READ_MAC Assist failed on device %s: 
x%x\n",
+                                CARD_BUS_ID(card), rc);
+               QETH_DBF_TEXT_(SETUP, 2, "1err%04x", rc);
+               /* fall back once more: */
        }
+
+       /* some devices don't support a custom MAC address: */
+       if (card->info.type == QETH_CARD_TYPE_OSM ||
+           card->info.type == QETH_CARD_TYPE_OSX)
+               return (rc) ? rc : -EADDRNOTAVAIL;
+       eth_hw_addr_random(card->dev);
+
 out:
        QETH_DBF_HEX(SETUP, 2, card->dev->dev_addr, card->dev->addr_len);
        return 0;
-- 
2.13.5