linux-kernel - [RFC PATCH 0/9] Remove useless on_each

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Message-Id: <1325600353-10895-1-git-send-email-gilad@benyossef.com>
Date:	Tue,  3 Jan 2012 16:19:04 +0200
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	linux-kernel@...r.kernel.org
Cc:	Gilad Ben-Yossef <gilad@...yossef.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	linuxppc-dev@...ts.ozlabs.org, devicetree-discuss@...ts.ozlabs.org,
	Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Matt Turner <mattst88@...il.com>, linux-alpha@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>, linux-ia64@...r.kernel.org,
	Will Deacon <will.deacon@....com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: [RFC PATCH 0/9] Remove useless on_each_cpu return value

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!

CC: Michal Nazarewicz <mina86@...a86.com>
CC: David Airlie <airlied@...ux.ie>
CC: dri-devel@...ts.freedesktop.org
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC: Paul Mackerras <paulus@...ba.org>
CC: Grant Likely <grant.likely@...retlab.ca>
CC: Rob Herring <rob.herring@...xeda.com>
CC: linuxppc-dev@...ts.ozlabs.org
CC: devicetree-discuss@...ts.ozlabs.org
CC: Richard Henderson <rth@...ddle.net>
CC: Ivan Kokshaysky <ink@...assic.park.msu.ru>
CC: Matt Turner <mattst88@...il.com>
CC: linux-alpha@...r.kernel.org
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: x86@...nel.org
CC: Tony Luck <tony.luck@...el.com>
CC: Fenghua Yu <fenghua.yu@...el.com>
CC: linux-ia64@...r.kernel.org
CC: Will Deacon <will.deacon@....com>
CC: Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC: Russell King <linux@....linux.org.uk>
CC: linux-arm-kernel@...ts.infradead.org

Gilad Ben-Yossef (9):
  arm: avoid using on_each_cpu hard coded ret value
  ia64: avoid using on_each_cpu hard coded ret value
  x86: avoid using on_each_cpu hard coded ret value
  alpha: avoid using on_each_cpu hard coded ret value
  ppc: avoid using on_each_cpu hard coded ret value
  agp: avoid using on_each_cpu hard coded ret value
  drm: avoid using on_each_cpu hard coded ret value
  smp: refactor on_each_cpu to void returning func
  x86: refactor wbinvd_on_all_cpus to void function

 arch/alpha/kernel/smp.c      |    7 ++-----
 arch/arm/kernel/perf_event.c |    2 +-
 arch/ia64/kernel/perfmon.c   |   12 ++----------
 arch/powerpc/kernel/rtas.c   |    3 +--
 arch/x86/include/asm/smp.h   |    5 ++---
 arch/x86/lib/cache-smp.c     |    4 ++--
 drivers/char/agp/generic.c   |    3 +--
 drivers/gpu/drm/drm_cache.c  |    3 +--
 include/linux/smp.h          |    7 +++----
 kernel/smp.c                 |    6 ++----
 10 files changed, 17 insertions(+), 35 deletions(-)

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