Re: [PATCH v2 0/2] Move net backend cleanup to NIC cleanup

[Eugenio Perez Martin]

On Fri, Dec 20, 2024 at 10:02 PM Michael Tokarev <mjt@tls.msk.ru> wrote:
>
> 12.09.2024 19:54, Eugenio Pérez wrote:
> > Commit a0d7215e33 ("vhost-vdpa: do not cleanup the vdpa/vhost-net
> > structures if peer nic is present") effectively delayed the backend
> > cleanup, allowing the frontend or the guest to access it resources as
> > long as the frontend NIC is still visible to the guest.
> >
> > However it does not clean up the resources until the qemu process is
> > over.  This causes an effective leak if the device is deleted with
> > device_del, as there is no way to close the vdpa device.  This makes
> > impossible to re-add that device to this or other QEMU instances until
> > the first instance of QEMU is finished.
> >
> > Move the cleanup from qemu_cleanup to the NIC deletion.
> >
> > v2:
> > Remove NIC peer also at net_cleanup. vhost-user trust all the
> > backends are clean before qemu removes char devices.
> >
> > This is not a requisite introduced by this commit as
> > system/runstate.c:qemu_cleanup shows.
> >
> > Eugenio Pérez (2):
> >    net: parameterize the removing client from nc list
> >    net: move backend cleanup to NIC cleanup
> >
> >   net/net.c        | 44 ++++++++++++++++++++++++++++++++++----------
> >   net/vhost-vdpa.c |  8 --------
> >   2 files changed, 34 insertions(+), 18 deletions(-)
> Hi!
>
> It looks like this series has been forgotten.  Is it still needed?
>
> In order for it to build, a single line in patch 2 needs to be
> changed (in net_cleanup()), from:
>
> +                for (int i = 0; i < queues; i++) {
> +                    NetClientState *nc = qemu_get_subqueue(nic, i);
> +                    qemu_cleanup_net_client(nc->peer, false);
> +                }
>
> to
>
> +                for (int i = 0; i < queues; i++) {
> +                    nc = qemu_get_subqueue(nic, i);
> +                    qemu_cleanup_net_client(nc->peer, false);
> +                }
>
> so there's no variable shadowing anymore.
>
> Should this series be resent (a v3), or can this be fixed at apply time?
>

I guess it is better to resend a v3, so we don't have a compiler
warning (or error). Jonah, maybe do you want to move this one forward?

Thanks!