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Date: Mon, 28 Apr 2008 02:31:39 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Gautham R Shenoy <ego@in.ibm.com>,
       Paul Jackson <pj@sgi.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched: missing locking in sched_domains code
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On Mon, 28 Apr 2008 11:17:45 +0200 Heiko Carstens <heiko.carstens@de.ibm.com> wrote:

> On Mon, Apr 28, 2008 at 01:57:23AM -0700, Andrew Morton wrote:
> > On Mon, 28 Apr 2008 10:49:04 +0200 Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
> > >  /* doms_cur_mutex serializes access to doms_cur[] array */
> > > -static DEFINE_MUTEX(doms_cur_mutex);
> > > +static DEFINE_MUTEX(sched_domains_mutex);
> > 
> > The comment refers to a no-longer-existing lock, and no longer correctly
> > describes the lock's usage.
> 
> version 42. Please feel free to change the comment if you think it could
> be better :)

Actually, it's a pretty bad comment ;)

> +/* sched_domains_mutex serializes calls to arch_init_sched_domains,
> + * detach_destroy_domains and partition_sched_domains.
> + */

locks protect *data*, not "calls".  This matters.  Which data is actually
protected by this lock??