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-rw-r--r--include/net/addrconf.h31
1 files changed, 31 insertions, 0 deletions
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 0c3ac5acb85f..b5474b1fcd83 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -91,6 +91,37 @@ int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2);
 void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr);
 void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr);
 
+static inline int addrconf_ifid_eui48(u8 *eui, struct net_device *dev)
+{
+	if (dev->addr_len != ETH_ALEN)
+		return -1;
+	memcpy(eui, dev->dev_addr, 3);
+	memcpy(eui + 5, dev->dev_addr + 3, 3);
+
+	/*
+	 * The zSeries OSA network cards can be shared among various
+	 * OS instances, but the OSA cards have only one MAC address.
+	 * This leads to duplicate address conflicts in conjunction
+	 * with IPv6 if more than one instance uses the same card.
+	 *
+	 * The driver for these cards can deliver a unique 16-bit
+	 * identifier for each instance sharing the same card.  It is
+	 * placed instead of 0xFFFE in the interface identifier.  The
+	 * "u" bit of the interface identifier is not inverted in this
+	 * case.  Hence the resulting interface identifier has local
+	 * scope according to RFC2373.
+	 */
+	if (dev->dev_id) {
+		eui[3] = (dev->dev_id >> 8) & 0xFF;
+		eui[4] = dev->dev_id & 0xFF;
+	} else {
+		eui[3] = 0xFF;
+		eui[4] = 0xFE;
+		eui[0] ^= 2;
+	}
+	return 0;
+}
+
 static inline unsigned long addrconf_timeout_fixup(u32 timeout,
 						   unsigned int unit)
 {