[PATCH RFC 1/3] net/tun: Ensure tun devices have a MAC address

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

A non-zero MAC address enables a network device to be assigned as
the underlying device for a virtual RDMA device. Without a non-
zero MAC address, cma_acquire_dev_by_src_ip() is unable to find the
underlying egress device that corresponds to a source IP address,
and rdma_resolve_address() fails.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 drivers/net/tun.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d4d0a41a905a..da85abfcd254 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1384,7 +1384,7 @@ static void tun_net_initialize(struct net_device *dev)
 
 		/* Point-to-Point TUN Device */
 		dev->hard_header_len = 0;
-		dev->addr_len = 0;
+		dev->addr_len = ETH_ALEN;
 		dev->mtu = 1500;
 
 		/* Zero header length */
@@ -1399,8 +1399,6 @@ static void tun_net_initialize(struct net_device *dev)
 		dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 		dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
 
-		eth_hw_addr_random(dev);
-
 		/* Currently tun does not support XDP, only tap does. */
 		dev->xdp_features = NETDEV_XDP_ACT_BASIC |
 				    NETDEV_XDP_ACT_REDIRECT |
@@ -1409,6 +1407,8 @@ static void tun_net_initialize(struct net_device *dev)
 		break;
 	}
 
+	eth_hw_addr_random(dev);
+
 	dev->min_mtu = MIN_MTU;
 	dev->max_mtu = MAX_MTU - dev->hard_header_len;
 }