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Message-ID: <20071128150055.GK20238@traven>
Date: Wed, 28 Nov 2007 16:00:55 +0100
From: Matthias Kaehlcke <matthias.kaehlcke@...il.com>
To: Larry Finger <larry.finger@...inger.net>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: Re: Question regarding mutex locking
El Wed, Nov 28, 2007 at 08:46:51AM -0600 Larry Finger ha dit:
> Matthias Kaehlcke wrote:
> > El Tue, Nov 27, 2007 at 10:37:00PM -0600 Larry Finger ha dit:
> >
> >> If a particular routine needs to lock a mutex, but it may be entered with that mutex already locked,
> >> would the following code be SMP safe?
> >>
> >> hold_lock = mutex_trylock()
> >>
> >> ...
> >>
> >> if (hold_lock)
> >> mutex_unlock()
> >
> > this is wont work, a mutex must not be released from another
> > context than the one that acquired it.
>
> I thought that mutex_trylock() returned 1 if it got the lock and 0 if not. If that is true, wouldn't
> the if statement only unlock if the lock was obtained in this routine?
you're right, sorry i read to fast and interpreted that you want to
release the mutex in any case
--
Matthias Kaehlcke
Linux Application Developer
Barcelona
You must have a plan. If you don't have a plan,
you'll become part of somebody else's plan
.''`.
using free software / Debian GNU/Linux | http://debian.org : :' :
`. `'`
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