Re: [PATCH net-next v2] net: virtio: use eth_hw_addr_set()

On Wed, Oct 27, 2021 at 11:31 PM Michael S. Tsirkin [off-list ref] wrote:

On Wed, Oct 27, 2021 at 08:20:12AM -0700, Jakub Kicinski wrote:

quoted

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@kernel.org>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Jason Wang <redacted>

quoted

---
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@redhat.com
CC: jasowang@redhat.com
CC: virtualization@lists.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