linux-kernel - Re: [GIT PULL] percpu fixes for 2.6.32-rc6

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Date:	Thu, 12 Nov 2009 19:11:15 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yhlu.kernel@...il.com>
Subject: Re: [GIT PULL] percpu fixes for 2.6.32-rc6

Hello, Ingo.

11/12/2009 04:57 AM, Ingo Molnar wrote:
> Sure - pulled it into tip:master for testing earlier today and after a 
> few hours of it's looking good so far in x86 runtime tests. I also did 
> cross-build testing to a dozen non-x86 architectures and it was fine 
> there too.

Great.

> btw., there's some 80-cols checkpatch warning artifacts in the commit:
> 
> +                       if (pcpu_extend_area_map(chunk, new_alloc) < 0) {
> +                               err = "failed to extend area map of "
> +                                       "reserved chunk";
> 
> which suggest that the logic here is perhaps nested a bit too deep. It 
> could be improved by moving the reserved allocation branch of 
> pcpu_alloc():

Strange, although the line break isn't the prettiest thing, the only
checkpatch problem I can see is the following.

  > scripts/checkpatch.pl 0001-percpu-restructure-pcpu_extend_area_map-to-fix-bugs-.patch 
  ERROR: trailing whitespace
  #80: FILE: mm/percpu.c:382:
  +^Ireturn new_alloc;^I$

  total: 1 errors, 0 warnings, 179 lines checked

  0001-percpu-restructure-pcpu_extend_area_map-to-fix-bugs-.patch has style problems, please review.  If any of these errors
  are false positives report them to the maintainer, see
  CHECKPATCH in MAINTAINERS.

The patch adds a trailing tab.  I'll fix that up (I usually catch
these while using quilt but this one didn't go through quilt and I
forgot to run checkpatch).

>         if (reserved && pcpu_reserved_chunk) {
> 
> into a helper inline function, something like __pcpu_alloc_reserved().
> 
> It's a rare special case anyway. It could be changed to return with the 
> pcpu_lock always taken, so the above branch would look like this:
> 
> 	if (unlikely(reserved)) {
> 		off = __pcpu_alloc_reserved(&chunk, size, align, &err);
> 		if (off < 0)
> 			goto fail_unlock;
> 		goto area_found;
> 	}
> 
> Which is a cleaner flow IMO, and which simplifes pcpu_alloc().

Hmmm... The thing is that the nesting isn't that deep there and
breaking string in the middle is something we do quite often.  What
checkpatch warning did you see?

Thanks.

-- 
tejun
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