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Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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Date: Thu, 15 Dec 2005 14:56:19 +0000
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To: Nikita Danilov <nikita@clusterfs.com>
Cc: Andrew Morton <akpm@osdl.org>, tglx@linutronix.de, dhowells@redhat.com, pj@sgi.com, mingo@elte.hu, hch@infradead.org, torvalds@osdl.org, arjan@infradead.org, matthew@wil.cx, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
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On Iau, 2005-12-15 at 16:41 +0300, Nikita Danilov wrote:
> But this change is about fixing bugs: mutex assumes that
> 
>  - only owner can unlock, and
> 
>  - owner cannot lock (immediate self-deadlock).

So add mutex_up/mutex_down that use the same semaphores but do extra
checks if lock debugging is enabled. All you need is an owner field for
debugging.

Now generate a trace dump on up when up and to check for sleeping on a
lock you already hold (for both sem and mutex).

Alan