linux-kernel - Re: [PATCH] smp.c: Quit unconditionally enabling irqs in on_each_cpu

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Date:	Mon, 12 Aug 2013 15:16:32 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	David Daney <ddaney@...iumnetworks.com>
Cc:	Gilad Ben-Yossef <gilad@...yossef.com>,
	Christoph Lameter <cl@...two.org>,
	David Daney <ddaney.cavm@...il.com>,
	<linux-kernel@...r.kernel.org>,
	Chris Metcalf <cmetcalf@...era.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	David Daney <david.daney@...ium.com>
Subject: Re: [PATCH] smp.c: Quit unconditionally enabling irqs in
 on_each_cpu_mask().

On Fri, 9 Aug 2013 12:24:56 -0700 David Daney <ddaney@...iumnetworks.com> wrote:

> > otherwise the bugs
> > stemming from incorrect use can be tricky to catch.
> >
> 
> ... all my patch does is allow on_each_cpu_mask() to be called with IRQs 
> disabled if we are in Early Boot.  This is already the case with 
> smp_call_function(), smp_call_function_many() and on_each_cpu().  I am 
> arguing that for the sake of consistency and the principle that function 
> behavior shouldn't be surprising, that we make on_each_cpu_mask() work 
> the same way.

Yup, the check in smp_call_function_many() will tell us if anyone calls
on_each_cpu_mask() with interrupts disabled any time after boot.

The whole early_boot_irqs_disabled thing is of course totally vile :(
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