[libvirt] [PATCH] macvtap: Work-around failing nl_connect calls (weird problem)

[Stefan Berger]

On 02/14/2011 02:51 PM, Daniel P. Berrange wrote:
>
> This approach feels like a nasty hack to me and potentially still leaves
> us with a problem in netcf which is also using netlink sockets. I think
> we need to get a clearer picture of what the root cause is before going
> for this kind of patch
Correct, I am 'fixing' this in the wrong place. The issues is in the 
call sequence

nl_handle = nl_handle_alloc()
nl_connect(nl_handle, NETLINK_ROUTE)

with the second one failing taking merely input from the 1st one. These 
are obviously two libnl calls. Something is either not using libn or not 
using it correctly.
Thanks for pointing out netcf. I looked at libnetcf code and found this 
sequence here:

[...]
int netlink_init(struct netcf *ncf) {

     ncf->driver->nl_sock = nl_handle_alloc();
     if (ncf->driver->nl_sock == NULL)
         goto error;
     if (nl_connect(ncf->driver->nl_sock, NETLINK_ROUTE) < 0) {
         goto error;
     }

This seems to be doing the same as I do. Maybe there is yet 'something 
else' that's using netlink sockets.
What's also strange is that the first 'virsh start' still works, but the 
subsequent 'virsh destroy' then does not.

    Stefan