Thread (7 messages) 7 messages, 3 authors, 2012-01-08

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

From: Gilad Ben-Yossef <gilad@benyossef.com>
Date: 2012-01-03 16:08:38
Also in: dri-devel, linux-alpha, linux-arm-kernel, linux-devicetree, lkml

2012/1/3 Michal Nazarewicz [off-list ref]:
On Tue, 03 Jan 2012 15:19:04 +0100, Gilad Ben-Yossef <gilad@benyossef.com=

wrote:
quoted
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,
Blimey! I'll resend with a proper Signed-off-by after more people have
a chance to
comment. And thanks for the review.
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. =A0With 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().
There are so many call site of smp_call_function() that do not check the
return value right now that I think we can tolerate it for just a
little bit longer
until that get fixed as well... :-)

Thanks,
Gilad


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Gilad Ben-Yossef
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gilad@benyossef.com
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