[ofa-general] Re: [PATCH] IPoIB: Remove redundant check in xmit handler

[Roland Dreier]

 > qdisc_run() first checks netif_queue_stopped(dev), and then if
 > it can get the __LINK_STATE_QDISC_RUNNING bit, it calls
 > __qdisc_run() which will do the actual xmit. Subsequent calls
 > to xmit within __qdisc_run checks for netif_queue_stopped.
 > 
 > So there is no way that xmit can be called with a stopped queue
 > as the core does it for every skb. And no other cpu can execute
 > this at the same time as the RUNNING bit is held. So this is a
 > completely safe removal of check for every skb.

Hmm, I don't see any changes that prevent the race I originally
described in http://oss.sgi.com/archives/netdev/2004-12/msg00474.html
Maybe your test may just not be able to hit the race, or am I missing
something?

Anyway medium-term I want to move IPoIB away from LLTX so this doesn't
matter that much.

 - R.