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Date: Thu, 5 Jul 2007 10:45:38 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Johannes Berg <johannes@sipsolutions.net>
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>
Subject: Re: [PATCH] debug work struct cancel deadlocks with lockdep
Message-ID: <20070705084538.GA3476@elte.hu>
References: <1183583529.9662.34.camel@johannes.berg>
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* Johannes Berg <johannes@sipsolutions.net> 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 = work->lockdep_map;
> +#endif

> +		lock_acquire(&lockdep_map, 0, 0, 0, 2, _THIS_IP_);
>  		f(work);
> +		lock_release(&lockdep_map, 1, _THIS_IP_);

neat trick :)

	Ingo