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

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Date:   Thu, 28 Oct 2021 10:30:34 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Jakub Kicinski <kuba@...nel.org>, davem <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH net-next v2] net: virtio: use eth_hw_addr_set()

On Wed, Oct 27, 2021 at 11:31 PM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Wed, Oct 27, 2021 at 08:20:12AM -0700, Jakub Kicinski wrote:
> > 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>
>
> Acked-by: Michael S. Tsirkin <mst@...hat.com>

Acked-by: Jason Wang <jasowang@...hat.com>

>
> > ---
> > 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
>