Re: [libvirt] [PATCHv3] lxc veth interfaces: fix interface name collisions

The previous veth interface naming scheme tried to find the lowest unused index for both the parent and container veth interfaces. That's susceptible to race conditions when multiple containers are started at the same time. Try to pick a random unused interface id for the parent if one wasn't given by the caller and use that as a template for the container interface name. This should prevent races to create two uniquely named interfaces for each container. The caller can still assign the parent interface name manually and that name is used for in container (before the interface is moved to the container namespace and renamed.) Signed-off-by: Oskari Saarenmaa <os(a)ohmu.fi&gt; --- My previous two patches for this issue were rejected because of concerns with the naming scheme (in v1) or leaving fixing the race condition to the caller (v2) and I mostly forgot about this issue after implementing a workaround in my application, but yesterday someone else on #virt ran into the same issue and I took another look at my patches. The third iteration of this patch uses random identifiers and makes sure they're not already in use, but still does not retry interface creation on failure. I believe this is good enough as the likelihood of two containers starting up at the same time and coming up with the same random 32-bit identifier should be rather low. This does change the interface names from nice low integers to random larger integers, but I don't see that an issue. And the caller can select any other name they like if that's not acceptable.