linux-kernel - Re: [PATCH v5 1/8] smp: Introduce a generic on_each_cpu

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Message-ID: <op.v7h259ad3l0zgt@mpn-glaptop>
Date:	Tue, 03 Jan 2012 09:57:35 +0100
From:	"Michal Nazarewicz" <mina86@...a86.com>
To:	"Gilad Ben-Yossef" <gilad@...yossef.com>
Cc:	linux-kernel@...r.kernel.org,
	"Chris Metcalf" <cmetcalf@...era.com>,
	"Peter Zijlstra" <a.p.zijlstra@...llo.nl>,
	"Frederic Weisbecker" <fweisbec@...il.com>,
	"Russell King" <linux@....linux.org.uk>, linux-mm@...ck.org,
	"Pekka Enberg" <penberg@...nel.org>,
	"Matt Mackall" <mpm@...enic.com>, "Rik van Riel" <riel@...hat.com>,
	"Andi Kleen" <andi@...stfloor.org>,
	"Sasha Levin" <levinsasha928@...il.com>,
	"Mel Gorman" <mel@....ul.ie>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Alexander Viro" <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, "Avi Kivity" <avi@...hat.com>
Subject: Re: [PATCH v5 1/8] smp: Introduce a generic on_each_cpu_mask function

> 2012/1/3 Michal Nazarewicz <mina86@...a86.com>:
>> on_each_cpu() returns an int.  For consistency reasons, would it make sense
>> to make on_each_cpu_maks() to return and int?  I know that the difference
>> is that smp_call_function() returns and int and smp_call_function_many()
>> returns void, but to me it actually seems strange and either I'm missing
>> something important (which is likely) or this needs to get cleaned up at
>> one point as well.

On Tue, 03 Jan 2012 09:12:21 +0100, Gilad Ben-Yossef <gilad@...yossef.com> wrote:
> I'd say we should go the other way around - kill the return value on
> on_each_cpu()
>
> The return value is always a hard coded zero and we have some code that tests
> for that return value. Silly...
>
> It looks like it's there for hysterical reasons to me :-)

That might be right.  Of course, this goes deeper then on_each_cpu() since
some of the smp_call_function functions have an int return value, but I
couldn't find an instance when they return non-zero.

I'd offer to volunteer to do the clean-up but I have too little experience
in IPI to say with confidence that we in fact can and want to drop the “int”
return value from all of those functions.

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +----<email/xmpp: mpn@...gle.com>--------------ooO--(_)--Ooo--
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