[openib-general] [PATCH] ipoib: dont lock tx on completion

[Roland Dreier]

    Michael> By testing again, and waking the net queue if completions
    Michael> arrived, we can avoid taking the tx lock on send
    Michael> completion in ip over ib, reducing the lock contention.

I really like the clever way of retesting after putting the queue to
sleep.  However I can't convince myself that some test or other will
be wrong because of stale values of tx_head or tx_tail, and I'm always
scared of code that requires multiple barriers and so on.  So I'm
going to defer applying this until I have time to think hard and make
sure there aren't any subtle races.

 - R.