Re: [PATCH 01/12] staging: lustre: fid: Use !x to check for kzalloc failure

From: Dan Carpenter
Date: Tue Jun 23 2015 - 05:23:23 EST

On Tue, Jun 23, 2015 at 08:25:05AM +0000, Dilger, Andreas wrote:
> I've found in the past that developers can introduce bugs when they treat
> return values as boolean when they really aren't.

I can imagine a bug like that where a function can return 0-2 and people

if (ret)

instead of:

if (ret == 1)

but that bug is something else besides pointers so it doesn't apply

What someone should do is try to measure it scientifically where we
flash some code on the screen and you have to press J for NULL and K for
non-NULL and we time it to the hundredth of a second. I have a feeling
that (NULL != foo) is the worst way to write it because of the double
negative Yoda code.

Yoda code is the most useless thing ever. I have actually measured this
and we introduce about 2 = vs == bugs per year. It's probably less now
that we have so many static checks against it. But people decided that
Yoda code was a good idea based on their gut instead of using statistics
and measurements and science.

dan carpenter

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