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

Julian Wiedmann
2018-04-26T07:42:24Z

From: Julian Wiedmann <jwi@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 <jwi@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