On Mon, Jun 27, 2022 at 02:36:56PM +0800, Jason Wang wrote:
> We used to call virtio_device_ready() after netdev registration.
s/used to call/currently call/
> This
> cause
s/This cause/Since ndo_open can be called immediately
after register_netdev, this means there exists/
> a race between ndo_open() and virtio_device_ready(): if
> ndo_open() is called before virtio_device_ready(), the driver may
> start to use the device before DRIVER_OK which violates the spec.
>
> Fixing
s/Fixing/Fix/
> this by switching to use register_netdevice() and protect the
> virtio_device_ready() with rtnl_lock() to make sure ndo_open() can
> only be called after virtio_device_ready().
>
> Fixes: 4baf1e33d0842 ("virtio_net: enable VQs early")
it's an unusual use of Fixes - the patch in question does not
introduce the problem, it just does not fix it completely.
But OK I guess.
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
With commit log changes:
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index db05b5e930be..8a5810bcb839 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3655,14 +3655,20 @@ static int virtnet_probe(struct virtio_device *vdev)
> if (vi->has_rss || vi->has_rss_hash_report)
> virtnet_init_default_rss(vi);
>
> - err = register_netdev(dev);
> + /* serialize netdev register + virtio_device_ready() with ndo_open() */
> + rtnl_lock();
> +
> + err = register_netdevice(dev);
> if (err) {
> pr_debug("virtio_net: registering device failed\n");
> + rtnl_unlock();
> goto free_failover;
> }
>
> virtio_device_ready(vdev);
>
> + rtnl_unlock();
> +
> err = virtnet_cpu_notif_add(vi);
> if (err) {
> pr_debug("virtio_net: registering cpu notifier failed\n");
> --
> 2.25.1
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