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- using INT_BUFSIZE_BOUND() to determine the length of the buffersize for printing and integer into - not explicitly initializing static var threadsTerminate to false anymore, since that's done automatically Changes after V2: - removed while looks in case of OOM error - removed on ifaceDown() call - preceding one ifaceDown() call with an ifaceCheck() call Since the name of an interface can be the same between stops and starts of different VMs I have to switch the IP address learning thread to use the index of the interface to determine whether an interface is still available or not - in the case of macvtap the thread needs to listen for traffic on the physical interface, thus having to time out periodically to check whether the VM's macvtap device is still there as an indication that the VM is still alive. Previously the following sequence of 2 VMs with macvtap device virsh start testvm1; virsh destroy testvm1 ; virsh start testvm2 would not terminate the thread upon testvm1's destroy since the name of the interface on the host could be the same (i.e, macvtap0) on testvm1 and testvm2, thus it was easily race-able. The thread would then determine the IP address parameter for testvm2 but apply the rule set for testvm1. :-( I am also introducing a lock for the interface (by name) that the thread must hold while it listens for the traffic and releases when it terminates upon VM termination or 0.5 second thereafter. Thus, the new thread for a newly started VM with the same interface name will not start while the old one still holds the lock. The only other code that I see that also needs to grab the lock to serialize operation is the one that tears down the firewall that were established on behalf of an interface. I am moving the code applying the 'basic' firewall rules during the IP address learning phase inside the thread but won't start the thread unless it is ensured that the firewall driver has the ability to apply the 'basic' firewall rules.
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>