Re: [RFC PATCH 0/9] Remove useless on_each_cpu return value
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- To: linux-kernel@xxxxxxxxxxxxxxx, "Gilad Ben-Yossef" <gilad@xxxxxxxxxxxxx>
- Subject: Re: [RFC PATCH 0/9] Remove useless on_each_cpu return value
- From: "Michal Nazarewicz" <mina86@xxxxxxxxxx>
- Date: Tue, 03 Jan 2012 15:25:49 +0100
- Cc: "David Airlie" <airlied@xxxxxxxx>, dri-devel@xxxxxxxxxxxxxxxxxxxxx, "Benjamin Herrenschmidt" <benh@xxxxxxxxxxxxxxxxxxx>, "Paul Mackerras" <paulus@xxxxxxxxx>, "Grant Likely" <grant.likely@xxxxxxxxxxxx>, "Rob Herring" <rob.herring@xxxxxxxxxxx>, linuxppc-dev@xxxxxxxxxxxxxxxx, devicetree-discuss@xxxxxxxxxxxxxxxx, "Richard Henderson" <rth@xxxxxxxxxxx>, "Ivan Kokshaysky" <ink@xxxxxxxxxxxxxxxxxxxx>, "Matt Turner" <mattst88@xxxxxxxxx>, linux-alpha@xxxxxxxxxxxxxxx, "Thomas Gleixner" <tglx@xxxxxxxxxxxxx>, "Ingo Molnar" <mingo@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, x86@xxxxxxxxxx, "Tony Luck" <tony.luck@xxxxxxxxx>, "Fenghua Yu" <fenghua.yu@xxxxxxxxx>, linux-ia64@xxxxxxxxxxxxxxx, "Will Deacon" <will.deacon@xxxxxxx>, "Peter Zijlstra" <a.p.zijlstra@xxxxxxxxx>, "Arnaldo Carvalho de Melo" <acme@xxxxxxxxxxxxxxxxxx>, "Russell King" <linux@xxxxxxxxxxxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
- In-reply-to: <1325600353-10895-1-git-send-email-gilad@benyossef.com>
- List-id: <linux-ia64.vger.kernel.org>
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On Tue, 03 Jan 2012 15:19:04 +0100, Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx> wrote:
on_each_cpu() returns as its own return value the return value of
smp_call_function(). smp_call_function() in turn returns a hard
coded value of zero.
Some callers to on_each_cpu() waste cycles and bloat code space
by checking the return value to on_each_cpu(), probably for
historical reasons.
This patch set refactors callers to not test on_each_cpu()
(fixed) return value and then refactors on_each_cpu to
return void to avoid confusing future users.
In other words, this patch aims to delete 18 source code lines
while not changing any functionality :-)
I tested as best as I could the x86 changes and compiled some
of the others, but I don't have access to all the needed hardware
for testing. Reviewers and testers welcome!
Other then the lack of Signed-off-by in the patches, looks good to me,
even though personally I'd choose a bottom-up approach, ie. make
smp_call_function() return void and from that conclude that
on_each_cpu() can return void. With those patches, we have a situation,
where smp_call_function() has a return value which is then lost for no
immediately apparent reason lost in on_each_cpu().
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +----<email/xmpp: mpn@xxxxxxxxxx>--------------ooO--(_)--Ooo--
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