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Date: Sun, 21 Nov 2004 18:54:39 -0800
From: Andrew Morton <akpm@osdl.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] del_timer() vs. mod_timer() SMP race
Message-Id: <20041121185439.7fcfe514.akpm@osdl.org>
In-Reply-To: <1101091445.13612.31.camel@gaston>
References: <1101091445.13612.31.camel@gaston>
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Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>
> --- linux-work.orig/kernel/timer.c	2004-11-22 11:50:59.000000000 +1100
>  +++ linux-work/kernel/timer.c	2004-11-22 13:35:38.928448032 +1100
>  @@ -308,6 +308,7 @@
>   		goto repeat;
>   	}
>   	list_del(&timer->entry);
>  +	smp_wmb();

Pretty please, always add a comment when putting an open-coded barrier into
the kernel.  Otherwise people cannot tell why it is there.