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Re: [libvirt] 答复: Re: [PATCH] qemu: change the name of tap device for a tapand bridge network



FYI your replies to messages on the list are almost impossible
to read & understand.

Your email client is sending HTML and badly mangled plain text.
Please make it send plain text only to public mailing lists,
with line wrapping and sensibly trim & quote text you are
replying to.

I can't see any comment you made in this latest message so I can't
reply to you.

On Tue, May 09, 2017 at 08:44:55AM +0800, lu zhipeng zte com cn wrote:
> On Mon, May 08, 2017 at 03:03:30PM +0800, ZhiPeng Lu wrote:>> In qemuProcessStop we explicitly remove the port from the openvswitch bridge after>> qemuProcessKill is called. But there is a certain interval of time between>> deleting tap device and removing it from bridge. The problem occurs when two vms>> start and shutdown with the same name's network interface attached to the same>> openvswitch bridge. When one vm with the nic named "vnet0" stopping, it deleted>>tap device without timely removing the port from bridge.>>.At this time, another vm created the tap device named "vnet0" and added port to the>> same bridge. Then, the first vm removed the port from the same bridge.>> Finally, the tap device of the second vm did not attached to the bridge.>> We need to delete the bridge port before deleting the tap device instead of after.>> So what's needed is to move the loop in qemuProcessStop that cleans up>> network interfaces so that it happens before qemuProcessKill is called.>This fix won't work correctly either. You cannot assume that libvirt has>control over when the QEMU process exits. It may exit itself *before*>libvirt runs any of its cleanup code.
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> On Mon, May 08, 2017 at 06:18:25PM +0800, lu zhipeng zte com cn wrote:> I may not have described it clearly.  > > i need to ensure  the order of  adding port to bridge and deleting from bridge.> > i  rename tap device to avoid the problem  in my first patch.i think it can solve the problem.> > my second patch may can't resolve the problem .> > Do you  have any better ideas?
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> 为了让您的VPlat虚拟化故障得到高效的处理,请上报故障到: $VPlat技术支持。
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> 芦志朋 luzhipeng
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> IT开发工程师 IT Development
> Engineer
> 操作系统产品部/中心研究院/系统产品 OS Product Dept./Central R&D Institute/System Product
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> 原始邮件
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> 发件人: <berrange redhat com>
> 收件人: <laine laine org>
> 抄送人: <libvir-list redhat com>芦志朋10108272
> 日 期 :2017年05月02日 16:41
> 主 题 :Re: [libvirt] [PATCH] qemu: change the name of tap device for a tapand bridge network
> 
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> On Fri, Apr 28, 2017 at 01:08:45PM -0400, Laine Stump wrote:
> > On 04/28/2017 05:33 AM, Daniel P. Berrange wrote:
> > > On Fri, Apr 28, 2017 at 05:23:19PM +0800, ZhiPeng Lu wrote:
> > >> Creating tap device and adding the device to bridge are not atomic operation.
> > >> Similarly deleting tap device and removing it from bridge are not atomic operation.
> > >> The Problem occurs when two vms start and shutdown. When one vm with the nic
> > >> named "vnet0" stopping, it deleted tap device but not removing port from bridge.
> > >> At this time, another vm created the tap device named "vnet0" and added port to the
> > >> same bridge. Then, the first vm deleted the tap device from the same bridge.
> > >> Finally, the tap device of the second vm don't attached to the bridge.
> > >> So, we can add domid to vm's nic name. For example, the vm's domid is 1 and vnet0
> > >> is renamed to vnet1.0.
> > > 
> > > Surely deleting the NIC automatically removes it from the bridge so we
> > > can just remove the code that delets the bridge port.
> > 
> > That is true when using a Linux host bridge, but I recall that for
> > openvswitch (which I think is what ZhiPeng is using, based on an earlier
> > patch), you must explicitly remove the port from the bridge - apparently
> > the port is still there in openvswitch's table as some sort of "zombie"
> > connection even after the tap device itself no longer exists.
> > 
> > 
> > But instead of changing the naming scheme, maybe we should just delete
> > the bridge port *before* deleting the tap device instead of after. (Am I
> > recalling correctly that the tap device is deleted automatically when
> > the qemu process is killed? If so, then what's needed is to move the
> > loop in qemuProcessStop() that cleans up network interfaces so that it
> > happens before qemuProcessKill() is called.
> 
> Agreed, we should just reverse the order.
> 
> Regards,
> Daniel
> -- 
> |: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
> |: https://libvirt.org         -o-            https://fstop138.berrange.com :|
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Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|


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