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> Have you seen any benefit of the rwsem over a simple mutex? I would guess
> that you can never even get into the situation where you get concurrent
> readers since I haven't found a single down_read() in your code, only
> downgrade_write()

We implemented a rwsem here because you can get concurrent readers.
My understanding is that downgrade_write() puts the rewem into the
same state as down_read().  Am I mistaken?