linux-kernel - Re: [PATCH 34/35] tick: Provide tick_suspend

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Date:	Tue, 17 Feb 2015 16:29:08 -0500 (EST)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
cc:	Peter Zijlstra <peterz@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	Russell King <rmk+kernel@....linux.org.uk>
Subject: Re: [PATCH 34/35] tick: Provide tick_suspend_local()

On Tue, 17 Feb 2015, Nicolas Pitre wrote:

> On Tue, 17 Feb 2015, Lorenzo Pieralisi wrote:
> 
> > On Mon, Feb 16, 2015 at 12:15:09PM +0000, Peter Zijlstra wrote:
> > > From: Thomas Gleixner <tglx@...utronix.de>
> > > 
> > > This function is intended to use by the freezer once the freezer folks
> > > solved their race issues. Also required to get rid of the ARM BL
> > > switcher tick hackery.
> > 
> > Totally agree with the patch(es), but I noticed that the ARM bL switcher
> > does not depend on PM_SLEEP, so I do not think you can compile
> > tick_{suspend/resume}_local() out if !PM_SLEEP, unless dependency
> > is enforced by the ARM bL switcher config but I do not think that
> > the config dependency really exists, Nico please correct me if I am
> > wrong.
> 
> The ARM bL switcher does not depend on PM_SUSPEND nor does it enforce it 
> because it currently doesn't need it.  So yeah, either PM_SUSPEND is 
> selected bringing quite a lot of code with it, or another symbol is used 
> for those functions (CONFIG_HOTPLUG_CPU maybe?).

Note the same problem exists with arch/x86/xen/suspend.c that calls 
tick_resume_local() yet this file is not subject to a dependency on 
CONFIG_PM_SUSPEND.


Nicolas
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