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Date: Tue, 11 Dec 2012 15:02:23 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20121211130223.GE15435@redhat.com>
References: <20121211055704.GA5080@t430s.nay.redhat.com>
	<20121211083843.GB23282@stefanha-thinkpad.muc.redhat.com>
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In-Reply-To: <20121211083843.GB23282@stefanha-thinkpad.muc.redhat.com>
Subject: Re: [Qemu-devel] Network isn't clean when qemu exits
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Amos Kong <akong@redhat.com>, Qemu Devel Mail List <qemu-devel@nongnu.org>

On Tue, Dec 11, 2012 at 09:38:43AM +0100, Stefan Hajnoczi wrote:
> On Tue, Dec 11, 2012 at 01:57:04PM +0800, Amos Kong wrote:
> > In vl.c:main(), tap device would be created when net_init_clients() is called.
> > "device" option is parsed after calling net_init_clients() by:
> > # "qemu_opts_foreach(qemu_find_opts("device"), device_init_func, NULL, 1)
> > 
> > Qemu will exit if fails to parse device parameters without calling net_cleanup().
> > I touch a problem, the tap device which is created by qemu-ifup script
> > could not be removed by qemu-ifdown script.
> > 
> > I did a quick fix, the tap device should be removed.
> > 
> > But there are many "exit(1)" after calling net_init_clients() in vl.c,
> > it's ugly to call net_cleanup() before each exit. Not sure if we have
> > other exit(1) in other sub-functions, which is also called after calling
> > net_init_clients().
> > 
> > Any comments?
> > 
> > =====
> > @@ -3882,8 +3889,11 @@ int main(int argc, char **argv, char **envp)
> >      }
> > 
> >      /* init generic devices */
> > -    if (qemu_opts_foreach(qemu_find_opts("device"), device_init_func,
> >      NULL, 1) != 0)
> > +    if (qemu_opts_foreach(qemu_find_opts("device"), device_init_func,
> > +                          NULL, 1) != 0) {
> > +        net_cleanup();
> >          exit(1);
> > +    }
> 
> How about qemu_add_exit_notifier() or atexit(3)?  Several other places
> in QEMU use this to clean up.
> 
> Then you can also remove net_cleanup() from the end of vl.c:main() since
> it gets called implicitly.
> 
> Stefan

Good idea, thanks a lot.