netdev - Re: linux-next: zillions of lockdep whinges in include/net/sock.h:1408

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Message-ID: <181815.1461532395@turing-police.cc.vt.edu>
Date:	Sun, 24 Apr 2016 17:13:15 -0400
From:	Valdis.Kletnieks@...edu
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: linux-next: zillions of lockdep whinges in include/net/sock.h:1408

On Sun, 24 Apr 2016 14:00:17 -0700, Eric Dumazet said:
> On Sun, 2016-04-24 at 15:56 -0400, Valdis.Kletnieks@...edu wrote:
> > On Sun, 24 Apr 2016 12:46:42 -0700, Eric Dumazet said:
> >
> > > >>> +	return !debug_locks ||
> > > >>> +	       lockdep_is_held(&sk->sk_lock) ||
> >
> > > Issue here is that once lockdep detected a problem (not necessarily in
> > > net/ tree btw), your helper always 'detect' a problem, since lockdep
> > > automatically disables itself.
> >
> > "D'Oh!" -- H. Simpson
> >
> > I thought this patch looked suspect, but couldn't put my finger on it. The
> > reason why I got like 41,000 of them is because I built a kernel that has
> > lockdep enabled, but I have an out-of-tree module that doesn't init something,
> > so I get this:
> >
> > [   48.898156] INFO: trying to register non-static key.
> > [   48.898157] the code is fine but needs lockdep annotation.
> > [   48.898157] turning off the locking correctness validator.
> >
> > After which point, even with this patch, every time through it's still going to
> > explode.
>
> Which patch are you talking about ?

The one that adds the !debug_locks check - once my out-of-kernel module
hits something that turns off lockdep, it's *still* going to complain on
pretty much all the same packets it complained about earlier.  I thought
it looked suspicious, but you clarified why...

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