Re: [PATCH net-next v6 5/8] vsock: add a netlink command to assign the g2h device to a netns

[Bobby Eshleman <bobbyeshleman@meta.com>]

On Sun, Nov 15, 2026 at 04:01:29AM +0000, netdev-bot+sashiko@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found more severe
> issue(s) in other patches of this series. This mail is only an FYI, in case
> you want to address the nit picks below when you respin.
> 
> Low priority / nit picks for your consideration:
> 
> - [Low] The new `vsock` generic netlink family defines `dev-netns-set`
>   (VSOCK_CMD_DEV_NETNS_SET) as a do-request with no reply.
> 
> --
> 
> vsock: add a netlink command to assign the g2h device to a netns
> 
> This patch adds a vsock generic netlink family. VSOCK_CMD_DEV_NETNS_SET
> moves the guest's G2H vsock device into a given network namespace, and
> VSOCK_CMD_DEV_NETNS_GET reports the assignment as an nsid relative to
> the caller. Connected sockets that can no longer reach the device are
> closed with ECONNRESET, and an assignment that would cause a CID
> collision is refused.
> 
> Link: https://lore.kernel.org/all/20200427142518.uwssa6dtasrp3bfc@steredhat/
> 
> > diff --git a/Documentation/netlink/specs/vsock.yaml b/Documentation/netlink/specs/vsock.yaml
> > new file mode 100644
> > index 0000000000000..f260ee88b1402
> > --- /dev/null
> > +++ b/Documentation/netlink/specs/vsock.yaml
> 
> [ ... ]
> 
> > +operations:
> > +  list:
> > +    -
> > +      name: dev-netns-set
> > +      doc: |
> > +        Set the network namespace of the guest's vsock device.
> 
> [ ... ]
> 
> > +        The assignment holds a reference on the namespace.
> > +      attribute-set: vsock
> > +      flags: [admin-perm]
> > +      do:
> > +        request:
> > +          attributes:
> > +            - netns-fd
> > +            - netns-pid
> 
> [Severity: Low]
> This isn't a bug, but should dev-netns-set have a reply block here?
> 
> The spec gives dev-netns-set a request and no reply. As a result,
> vsock_nl_dev_netns_set_doit() only returns an errno and the caller gets a
> bare ACK.
> 
> The netlink guidance for new families says every operation should reply
> with a full message that identifies the resulting object. It also says
> that once a command only ACKs, the ACK-only behaviour becomes uAPI and
> cannot be changed later.
> 
> The v3 revision replied with netns-id. The v5 changelog says the reply
> was dropped at Stefano's request, so this looks deliberate. Since this
> family has not been released yet, could that decision be checked once
> more?
> 
> A netns-id reply would tell the caller where the device ended up,
> relative to its own namespace, without a second dev-netns-get request.

Actually, now that we're taking a netns-fd/netns-pid, the reply makes
sense because it can be something besides the current netns.

pw-bot: cr

-Bobby

> 
> > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > index 37abde1ca26cd..d4d88c8cf142f 100644
> > --- a/net/vmw_vsock/af_vsock.c
> > +++ b/net/vmw_vsock/af_vsock.c
> 
> [ ... ]
> 
> > +int vsock_nl_dev_netns_set_doit(struct sk_buff *skb, struct genl_info *info)
> > +{
> 
> [ ... ]
> 
> > +	err = vsock_g2h_net_assign(net, info->extack);
> > +	put_net(net);
> > +
> > +	return err;
> > +}
> 
> This is where a reply would be built, for example by reusing
> vsock_nl_dev_netns_fill() as vsock_nl_dev_netns_get_doit() does.
> 
> -- 
> Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261113-vsock-guest-ns-v6-0-3737ce4673c0%40meta.com