Re: q == &noop_qdisc warning from 802.11 code

[David Miller <davem@davemloft.net>]

From: Johannes Berg <johannes@sipsolutions.net>
Date: Wed, 23 Jul 2008 16:53:05 +0200

> 
> > I also hit a bug related to noop_qdisc running the net-next kernel. 
> > I hit this bug every time I run "ifconfig eth0 mtu 9000; ifconfg eth0 1500" for any
> > interface (tested against s2io and e1000) that is up, otherwise the bug isn't
> > reproducible.
> > 
> > The bug dumps the following calltrace: 
> > 
> > [root@io-dolphins net-next-2.6]# ifconfig eth0  mtu 9000; ifconfig eth0 mtu 1500
> > ------------[ cut here ]------------
> > kernel BUG at net/core/dev.c:1328!
> 
> > void __netif_schedule(struct Qdisc *q)
> > {
> >         BUG_ON(q == &noop_qdisc);
> > 
> > So, somehow we're reaching __netif_schedule() using a noop_qdisc. 
> 
> Yeah, I'm looking into it. Just removing the netif_wake calls in mlme.c
> might work.

Don't work too hard on this now, I'm removing the warning as I mentioned
in a recent posting.

Most important is the bug where wireless expects the SKB control block
to be untouched across the qdisc layer, which was never true :-)