linux-kernel - Re: [PATCH] scripts: improve checkstack

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Message-ID: <20100222084339.1367cfe6@nehalam>
Date:	Mon, 22 Feb 2010 08:43:39 -0800
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Cong Wang <amwang@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Luis R. Rodriguez" <lrodriguez@...eros.com>,
	Sam Ravnborg <sam@...nborg.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	Uwe Kleine-KÃ¶nig 
	<u.kleine-koenig@...gutronix.de>,
	"Robert P. J. Day" <rpjday@...shcourse.ca>,
	Arnd Bergmann <arnd@...db.de>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Hui Zhu <teawater@...il.com>,
	Ozan Ãaglayan <ozan@...dus.org.tr>,
	Matthew Wilcox <willy@...ux.intel.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Li Hong <lihong.hi@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Matt Fleming <matt@...sole-pimps.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scripts: improve checkstack

On Sat, 20 Feb 2010 15:35:06 +0800
Cong Wang <amwang@...hat.com> wrote:

> Stephen Hemminger wrote:
> > Turn on strict checking, and get rid of annoying use of prototype.
> > Fix syntax error in declaration
> > 
> > Use efficient sort algorithm by using schwartzian transform.
> >   http://en.wikipedia.org/wiki/Schwartzian_transform
> 
> 
> Yeah, the idea is good, this can also make it more perlish. ;)
> 
> But...
> 
> 
> > -print sort bysize @stack;
> > +# Use Schwartzian transform to sort by last field (size)
> > +print map { $_->[0] }
> > +      sort { $b->[1] <=> $a->[1] }
> > +      map { [$_, /:\t*(\d+)$/] } @stack;
> 
> This regex here is not strictly the same as before.
> 
> Can we just keep the original regex? If not, what's wrong?

The original one had extra cruft:
  1. The expression is anchored on right, so leading .* is meaningless
  2. Putting tab directly makes it invisible when reading source (use \t)
  3. Want to match on number, not just anything (that is why the \d)
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