netdev - [PATCH net-next v2] net: virtio: use eth_hw_addr

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Date:   Wed, 27 Oct 2021 08:20:12 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        mst@...hat.com, jasowang@...hat.com,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH net-next v2] net: virtio: use eth_hw_addr_set()

Commit 406f42fa0d3c ("net-next: When a bond have a massive amount
of VLANs...") introduced a rbtree for faster Ethernet address look
up. To maintain netdev->dev_addr in this tree we need to make all
the writes to it go through appropriate helpers.

Even though the current code uses dev->addr_len the we can switch
to eth_hw_addr_set() instead of dev_addr_set(). The netdev is
always allocated by alloc_etherdev_mq() and there are at least two
places which assume Ethernet address:
 - the line below calling eth_hw_addr_random()
 - virtnet_set_mac_address() -> eth_commit_mac_addr_change()

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
v2: - actually switch to eth_hw_addr_set() not dev_addr_set()
    - resize the buffer to ETH_ALEN
    - pass ETH_ALEN instead of dev->dev_addr to virtio_cread_bytes()

CC: mst@...hat.com
CC: jasowang@...hat.com
CC: virtualization@...ts.linux-foundation.org
---
 drivers/net/virtio_net.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index c501b5974aee..cc79343cd220 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3177,12 +3177,16 @@ static int virtnet_probe(struct virtio_device *vdev)
 	dev->max_mtu = MAX_MTU;
 
 	/* Configuration may specify what MAC to use.  Otherwise random. */
-	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
+		u8 addr[ETH_ALEN];
+
 		virtio_cread_bytes(vdev,
 				   offsetof(struct virtio_net_config, mac),
-				   dev->dev_addr, dev->addr_len);
-	else
+				   addr, ETH_ALEN);
+		eth_hw_addr_set(dev, addr);
+	} else {
 		eth_hw_addr_random(dev);
+	}
 
 	/* Set up our device-specific information */
 	vi = netdev_priv(dev);
-- 
2.31.1