[Libvir] FYI: bug in remote code

[Daniel P. Berrange]

On Tue, Oct 16, 2007 at 02:52:27PM -0400, Mark Johnson wrote:
> I ran into a bug in the remote code...
> 
> I was doing
>   # virsh -c xen_tcp://<ip_addr>/
> 
> It you don't have qemu compiled in, you will hang in in libvirtd in
> 
> do_open()
>    res = virNetworkDriverTab[i]->open (ret, name, flags);
> 
> when trying to open the remote network driver. Usually qemu
> returns success and you fall out of the loop before you call
> this (which is why you won't see it with qemu support built in).
> 
> You hang in libvirtd trying to read from the libvirtd PF_UNIX
> socket. You read from the socket because you hit this code
> path in doRemoteOpen()
> 
>     if (!uri->server && !transport_str) {
>         if (flags & VIR_DRV_OPEN_REMOTE_UNIX) {
>             transport = trans_unix;
> 
> No idea what it should be doing? :-)

That means if you don't specify a server / transport, it'll try to use
the local libvirtd daemon. ie, it supports  qemu:///system  URIs 
So this is the correct thing to be doing, but the open question is why
it would hang. If libvirtd isn't running locally it should give you
back an immediate rejection / failure, not hang in read.

> I reproduced it on todays CVS bits on FC7 by commenting out qemu's
> network register..
> 
> int qemudRegister(void) {
>     virRegisterDriver(&qemuDriver);
>     /* virRegisterNetworkDriver(&qemuNetworkDriver); */
>     virRegisterStateDriver(&qemuStateDriver);
>     return 0;
> }

I'll give that a try.


Dan.
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