linux-kernel - Re: [PATCH] use spinlock instead of binary mutex in idt77252 driver

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Message-ID: <20070423075722.GE10339@traven>
Date:	Mon, 23 Apr 2007 09:57:22 +0200
From:	Matthias Kaehlcke <matthias.kaehlcke@...il.com>
To:	"Eddie C. Dost" <ecd@...com.com>
Cc:	Kyle Moffett <mrmacman_g4@....com>, chas@....nrl.navy.mil,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] use spinlock instead of binary mutex in idt77252 driver

hi,

El Mon, Apr 23, 2007 at 09:40:19AM +0200 Eddie C. Dost ha dit:

> as long as mutexes are not converted to nop when CONFIG_SMP is not
> defined (I don't know what current kernels do), this is of course
> correct. You need to verify the headerfiles for the above.

i just checked this, neither the mutex header nor implementation files
handle things different for CONFIG_SMP. 

thanks for your comments

> On Mon, Apr 23, 2007 at 09:40:26AM +0200, Matthias Kaehlcke wrote:
> > El Mon, Apr 23, 2007 at 09:16:08AM +0200 Eddie C. Dost ha dit:
> >  
> > > Please note that the semaphore is used to lock the idt77252 config
> > > tables among multiple users including atmsigd even on single processor
> > > machines. Does this work with mutexes?
> > 
> > afaik mutexes have the same behaviour as binary semaphores that are
> > used as mutexes (always locked and unlocked by the same
> > process/thread):
> > 
> > ".. the semaphore type can officially be considered to be on its way
> > out. New code should not use semaphores, and old code which uses
> > semaphores as mutexes should be converted over when an opportunity
> > presents itself."
> > 
> > http://lwn.net/Articles/167034/
> > 
> > please correct me if i'm wrong, i'm just doing my first steps with
> > linux kernel development

-- 
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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