linux-kernel - Re: [RFC][PATCH 1/5] x86: Remove const_udelay() caring about which cpu var it uses

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Date:	Mon, 19 Sep 2011 19:31:32 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Christoph Lameter <cl@...two.org>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Christoph Lameter <cl@...ux.com>
Subject: Re: [RFC][PATCH 1/5] x86: Remove const_udelay() caring about which
 cpu var it uses

On Mon, 2011-09-19 at 16:51 -0500, Christoph Lameter wrote:
> On Mon, 19 Sep 2011, Steven Rostedt wrote:
> 
> > The __const_udelay() code originally used raw_smp_processor_id()
> > in its calculations for a delaying. Probably because if it were
> > to migrate, it would take much longer to do so than the requested
> > delay.
> >
> > Switch from this_cpu_read() to __this_cpu_read() to document that
> > the read is racy and we do not care.
> 
> Is preemption disabled by all callers to __const_udelay?

Nope, because I triggered a splat with it :-) From lots of places.

-- Steve


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