Re: lockdep trace from rc2.

[Stephen Hemminger <shemminger@vyatta.com>]

On Tue, 26 Feb 2008 18:13:54 -0800 (PST)
David Miller <davem@davemloft.net> wrote:

> From: Dave Jones <davej@codemonkey.org.uk>
> Date: Sun, 24 Feb 2008 21:22:37 -0500
> 
> > https://bugzilla.redhat.com/show_bug.cgi?id=431038 has some more info,
> > but the trace is below...
> > I'll get an rc3 kernel built and ask the user to retest, but in case this
> > isn't a known problem, I'm forwarding this here.
> 
> So basically, tulip's ->stop() calls tulip_down() which does a
> flush_scheduled_work().
> 
> Lockdep is saying that the RTNL mutex (which is held when we
> call the driver's ->stop() method) conflicts with that work
> queue lock that flush_scheduled_work() takes.
> 
> Maybe this has something to do with how linkwatch works, but
> I can't say that I've seen this before nor do I quite understand
> what lockdep doesn't exactly like here.
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This has come up before in other drivers,
you can't call flush_scheduled_work under RTNL.
See:  http://article.gmane.org/gmane.linux.network/86941