Re: [PATCH V2] mac80211: Revise,pending queue depth in ieee80211_local data structure

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2010-03-31 at 17:12 +0900, Bruno Randolf wrote:
> On Tuesday 23 March 2010 03:12:44 you wrote:
> > On Sun, 2010-03-21 at 11:01 +0900, Bruno Randolf wrote:
> > > On Sunday 21 March 2010 05:40:05 Johannes Berg wrote:
> > > > On Sat, 2010-03-20 at 21:02 +0100, Lorenzo Bianconi wrote:
> > > > > >> setup 2 wireless cards, talking to each other (i use IBSS) on
> > > > > >> different
> > > > > 
> > > > > >> machines. then setup routing like this:
> > > > > PC1<--ethernet cable-->Device1<--wireless link-->Device2<--ethernet
> > > > > cable-->PC2
> > > > 
> > > > I'm not really sure how this scenario differs from injecting traffic
> > > > locally, but I'll try to reproduce.
> > > 
> > > if you generate traffic locally it's enough to stop the queues, this will
> > > cause userspace to stop generating traffic. in the forwarding case (which
> > > we are talking about) stopping the queues will not stop the sender to
> > > send traffic, thus we have to start dropping packets at some point.
> > 
> > So I tried this scenario, and I see the queues stopping, and traffic
> > being dropped quite as you'd want it. Even the race condition that I
> > noticed didn't ever trigger.
> > 
> > Please make sure you're using a kernel recent enough to include the
> > fixes, maybe try compat-wireless.
> 
> so it must be an ath5k bug then... lorenzo's description just resembled my 
> case so much, that i thought it could be the same bug. sorry to have bothered 
> you with this...

I don't think there's any way this can be a driver bug, assuming it
stops the queues properly, which it has to unless it comes up with its
own queueing scheme...

johannes