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Subject: Re: [PATCH] debug work struct cancel deadlocks with lockdep
From: Johannes Berg <johannes@sipsolutions.net>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
       Oleg Nesterov <oleg@tv-sign.ru>, Arjan van de Ven <arjan@infradead.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Thomas Sattler <tsattler@gmx.de>
In-Reply-To: <20070705084538.GA3476@elte.hu>
References: <1183583529.9662.34.camel@johannes.berg>
	 <20070705084538.GA3476@elte.hu>
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Date: Thu, 05 Jul 2007 10:50:48 +0200
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On Thu, 2007-07-05 at 10:45 +0200, Ingo Molnar wrote:

> > +#ifdef CONFIG_LOCKDEP
> > +		/*
> > +		 * It is permissible to free the struct work_struct
> > +		 * from inside the function that is called from it,
> > +		 * this we need to take into account for lockdep too.
> > +		 * To avoid bogus "held lock freed" warnings as well
> > +		 * as problems when looking into work->lockdep_map,
> > +		 * make a copy and use that here.
> > +		 */
> > +		struct lockdep_map lockdep_map =3D work->lockdep_map;
> > +#endif
>=20
> > +		lock_acquire(&lockdep_map, 0, 0, 0, 2, _THIS_IP_);
> >  		f(work);
> > +		lock_release(&lockdep_map, 1, _THIS_IP_);
>=20
> neat trick :)

Not like I had a choice ;) But since I assign .key it still works :)

Btw, do you have a tree you'll submit this through, or Oleg, or should I
send it to akpm after we sort out any further issues?

johannes

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