linux-kernel - Re: Regression :-) Re: [GIT PULL RESEND] x86/jumpmplabel changes for v3.12-rc1

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Message-ID: <20130911135237.245386fb@gandalf.local.home>
Date:	Wed, 11 Sep 2013 13:52:37 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Jason Baron <jbaron@...mai.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	boris.ostrovsky@...cle.com, david.vrabel@...rix.com
Subject: Re: Regression :-) Re: [GIT PULL RESEND] x86/jumpmplabel changes
 for v3.12-rc1

On Wed, 11 Sep 2013 13:25:52 -0400
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> wrote:


> commit 97ce2c88f9ad42e3c60a9beb9fca87abf3639faa
> Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
> Date:   Wed Oct 12 16:17:54 2011 -0700
> 
>     jump-label: initialize jump-label subsystem much earlier
>     
>     Initialize jump_labels much, much earlier, so they're available for use
>     during system setup.
>     
>     Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
>     Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> 
> 
> implies that yes.

Unfortunately it does not. All that patch did was move
jump_label_init() up more. If anything, it implies "no".

The question is, can we enable jump_labels before jump_label_init()?

Note, we may still be able to (as it seems to work), the thing is, the
only thing that static_key_slow_inc() does is to tell jump_label_init()
to enable it. Before jump_label_init() is called, nothing has changed.
No code modification, all users of paravirt_ticketlocks_enabled are
still off.

-- Steve
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