Re: [Qemu-devel] [PATCH] net: synchronize net_host_device_remove with host_net_remove_completion

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Fri, Feb 06, 2015 at 03:46:42PM +0100, Paolo Bonzini wrote:
> 
> 
> On 06/02/2015 14:54, Stefan Hajnoczi wrote:
> > On Mon, Jan 19, 2015 at 12:27:11PM +0100, Paolo Bonzini wrote:
> >> On 02/01/2015 17:20, Paolo Bonzini wrote:
> >>>>>
> >>>>> The assert can be dropped completely since the code already has an
> >>>>> equivalent assert:
> >>>>>
> >>>>>   queues = qemu_find_net_clients_except(nc->name, ncs,
> >>>>>                                         NET_CLIENT_OPTIONS_KIND_NIC,
> >>>>>                                         MAX_QUEUE_NUM);
> >>>>>   assert(queues != 0); <-- fail if type == NET_CLIENT_OPTIONS_KIND_NIC
> >>> I left it on purpose for documentation, but I'll send v2 next week that
> >>> removes it.
> >>
> >> Actually it's not the same.  If you have "-netdev user,id=e1000 -device
> >> e1000,netdev=e1000" you will be able to call qemu_del_net_client on the
> >> NIC, and it will _not_ fail if the assertion is removed.
> > 
> > I don't follow.
> > 
> > If you call qemu_del_net_client(e1000_nic) then
> > qemu_find_net_clients_except(nc->name, ncs, NET_CLIENT_OPTIONS_KIND_NIC,
> > MAX_QUEUE_NUM) returns 0.  This causes the assert(queues != 0) to fail.
> 
> NICs and other clients are in separate namespaces.  So if you do
> 
>    -netdev user,id=e1000
>    -device e1000,netdev=e1000,id=e1000
> 
> you have two NetClients named "e1000".  If you call (by mistake)
> qemu_del_net_client(e1000_nic), qemu_find_net_clients_except will return
> the SLIRP client and the assertion will not fail.

Thanks for explaining.

Applied to my net tree:
https://github.com/stefanha/qemu/commits/net

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