Hi,
I told Linus and Marek that the implementation of some datastructures using reference counting and RCUs must be redesigned. The problem is that call_rcu should only be used when the reference count is zero because multiple call_rcu cannot be initiated at the same time. The next problem is that we may try to access an element with the refcount 0 when we try to traverse a rcu protected list. This problem cannot be solved by kref - thus we have to use atomic_t again to not increase the reference count when it was already zero.
I reviewed the posted patches, filled in the missing parts and fixed some bugs along the way. Feel free to comment.
@Linus: I believe it would be a good idea if your gateway patch was based on this patchset.
Cheers, Marek