Synchronizing if_xennet_xenbus detach with event-handling

[Rohan Desai <desai.p.rohan%gmail.com@localhost>]

I'm getting a panic due to a race between the detach path (xennet_xenbus_detach) and event handling (xennet_handler called from triggered event channel). xennet_xenbus_detach frees up the tx ring and xennet_handler tries to access it. I'm not sure what event the event channel is being poked for (tx complete, rx ready, other). Does anybody know how these two code-paths are supposed to be synchronized ?