[RFC PATCH 0/9] Remove useless on_each_cpu return value

Gilad Ben-Yossef gilad at benyossef.com
Wed Jan 4 01:19:04 EST 2012

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 at mina86.com>
CC: David Airlie <airlied at linux.ie>
CC: dri-devel at lists.freedesktop.org
CC: Benjamin Herrenschmidt <benh at kernel.crashing.org>
CC: Paul Mackerras <paulus at samba.org>
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CC: linuxppc-dev at lists.ozlabs.org
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CC: Richard Henderson <rth at twiddle.net>
CC: Ivan Kokshaysky <ink at jurassic.park.msu.ru>
CC: Matt Turner <mattst88 at gmail.com>
CC: linux-alpha at vger.kernel.org
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CC: Ingo Molnar <mingo at redhat.com>
CC: "H. Peter Anvin" <hpa at zytor.com>
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CC: Tony Luck <tony.luck at intel.com>
CC: Fenghua Yu <fenghua.yu at intel.com>
CC: linux-ia64 at vger.kernel.org
CC: Will Deacon <will.deacon at arm.com>
CC: Peter Zijlstra <a.p.zijlstra at chello.nl>
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CC: Russell King <linux at arm.linux.org.uk>
CC: linux-arm-kernel at lists.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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