Message-ID: <3C596533.488F1470@dlr.de>
Date: Thu, 31 Jan 2002 16:39:31 +0100
From: Martin Wirth <Martin.Wirth@dlr.de>
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To: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2.5: push BKL out of llseek
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Sender: linux-kernel-owner@vger.kernel.org

On 30 Jan 2002, Martin Wirth wrote:
>
>void combi_mutex_lock(struct combilock *x)
.....
>       } else <---
>              x->owner=current;  
>       spin_unlock(&x->wait.lock);

Uugh, the else is wrong of course. The owner has to be set in any
case.(Just deleted some debugging code and reformatted a bit to quick
:))

A further note: Although the combilock shares some advantages with a
spin-lock (no unnecessary scheduling for short time locking) it may
behave like a semaphore on entry also if you call combi_spin_lock.
For example

       spin_lock(&slock);
       combi_spin_lock(&clock);

is a BUG because combi_spin_lock may sleep while holding slock!

Would be nice if there were some comments.

Martin Wirth
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