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Date: Mon, 31 Jul 2017 17:04:11 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: jkosina@suse.cz, masami.hiramatsu.pt@hitachi.com, hpa@linux.intel.com,
        linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [RFC][PATCH]: x86: clarify/fix no-op barriers for text_poke_bp()
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On Mon, Jul 31, 2017 at 10:23:23AM -0400, Steven Rostedt wrote:
> > -	smp_wmb();
> 
> Heh, I think this was a "lets not leak bp_patching_in_progress" out of
> this function. But I don't see any harm if it happens.
> 
> As this function was a *very* slow path, that smp_wmb() was a "it's not
> really needed, but it wont hurt anything to slap it in there just in
> case".

Well, this is x86, its a NO-OP. The only reason to write barriers like
that is for documentation purposes and in that regard is confuses. IOW
has negative value.