Hi Cong,
On Tue, May 30, 2017 at 04:18:17PM -0700, Cong Wang wrote:
> On Tue, May 30, 2017 at 3:07 PM, Harald Welte <lafo...@gnumonks.org> wrote:
> > But, to the contrary, this doesn't happen. The unshare-created netns is
> > gone, but the netdevice did not get moved back to the root namespace
> > either. The only hack to get back to the "eth0" device is to unload the
> > driver and re-load it.
>
>
> Net namespace simply unregisters all netdevices inside when it is
> gone, no matter where they are from.
ah, ok. I missed that part. Is there a good piece of documentation on
netwokr namespaces that I should read?
> I am pretty sure you can move it back to root-ns if you want,
Yes, I can explicitly do that, but this of course doesn't work if e.g.
my [single] process in that namespace crashes due to some bug, OOM or
the like.
> it is a little tricky because you have to give the root-ns a name
> first.
It's actually not, as you can just identify the root-ns by pid 1, so
"ip link set $DEV netns 1" will move it back. As indicated, I'm worried
about the error paths.
> > What am I missing here? Is this the intended behavior?
>
> Yes it is.
thanks for your confirmation. Guess I have to get used to it.
> > Of course I know I could simply do something like "ip link set eth0
> > netns 1" from within the namespace before leaving. But what if the
> > process is not bash and the process exits abnormally? I'd consider
> > that explicit reassignment more like a hack than a proper solution...
>
> It doesn't make sense to move it back to where it is from, for example,
> what if you move a veth0 from netns1 to netns2 and netns1 is gone
> before netns2?
for virtual devices, I would agree. For physical devices, I think the
default behavior to unregister them is - from my of course very
subjective point of view - quite questionable.
Regards,
Harald
--
- Harald Welte <lafo...@gnumonks.org> http://laforge.gnumonks.org/
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