linux-kernel - Re: [RFC PATCH] x86: Add safe_udelay() and safe

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Date:	Tue, 11 Jan 2011 21:07:59 -0800
From:	Greg KH <greg@...ah.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux.com>, Tejun Heo <tj@...nel.org>
Subject: Re: [RFC PATCH] x86: Add safe_udelay() and safe_msleep()

On Wed, Jan 12, 2011 at 01:32:45PM +1100, Benjamin Herrenschmidt wrote:
> On Tue, 2011-01-11 at 17:06 -0800, Yinghai Lu wrote:
> > We need to use those function in early-quirk stage with code that is shared with
> > later stage.
> > 
> > for x86, normal udelay() will need to wait per_cpu(cpu_info) is allocated... that i
> > after smp_prepare_cpus(), because it need to use percpu.loops_per_jiffy.
> > 
> > Also msleep() will need to wait schedular is ready.
> > 
> > Try to have one early version udelay that use loops_per_jiffy directly.
> > and early msleep is just early delay.
> > 
> > This patch will set safe_udelay to early in x86 early arch code, and then init/main.c
> > will set them back.
> 
> I still think it's better to just make msleep() work with and without
> scheduler and avoid having to bother with a new API

I agree, this patch just makes things really complicated for no reason.

Again, I still fail to see why you are doing this patch series in the
first place...

thanks,

greg k-h
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