linux-kernel - Re: [PATCH] uio.c: Fix warning: 'ret' might be used uninitialized

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Message-ID: <20121201035625.GC2603@local>
Date:	Sat, 1 Dec 2012 04:56:25 +0100
From:	"Hans J. Koch" <hjk@...sjkoch.de>
To:	Cong Ding <dinggnu@...il.com>
Cc:	"Hans J. Koch" <hjk@...sjkoch.de>,
	Vitalii Demianets <vitas@...factor.kiev.ua>,
	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] uio.c: Fix warning: 'ret' might be used uninitialized

On Sat, Dec 01, 2012 at 02:22:44AM +0100, Cong Ding wrote:
> On Fri, Nov 30, 2012 at 10:33 PM, Hans J. Koch <hjk@...sjkoch.de> wrote:
> > On Fri, Nov 30, 2012 at 12:12:46PM +0100, Tux9 wrote:
> >> I like Vitalii's solution more. Hans's solution assign the value
> >> -ENOMEM to ret in every round of the loop, which is a kind of wasting
> >> CPU cycles.
> >
> > The difference between
> > 1 files changed, 12 insertions(+), 4 deletions(-) and
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > is more important. Note that this code is not in a fast path but only
> > called once at device creation.
> Why do you think the size of the patch is so important? I think the
> most important thing is the coding style and efficiency. I agree
> efficiency is not important in this case, but what about coding style?

Most important. Short is beautiful.

> Your code is _not_ very easy to understand.

You think so?

> It's a very natural thing
> to set the return value and then goto the error-handling codes, which
> is exactly same as what Vitalii did, rather than setting an initial
> value in the beginning of each round of the loop as you did.

Setting a default value at the beginning of a block is the most natural
thing. I don't want to repeat the same code in three places.

> There are
> also a bunch of codes in kernel in the same style with Vitalii, but I
> cannot find anything same as your codes.

If you follow LKML closely, you'll notice that simplifying code by
replacing unnecessary repetitions with shorter versions is always welcome.
If we didn't go for that, the kernel source would be a few million lines
bigger by now.

Thanks,
Hans
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