linux-kernel - Re: Please don't replace numeric parameter like 0444 with macro

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Message-ID: <20160803004226.GF2356@ZenIV.linux.org.uk>
Date:	Wed, 3 Aug 2016 01:42:26 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Pavel Machek <pavel@....cz>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Baole Ni <baolex.ni@...el.com>,
	Russell King - ARM Linux <linux@...linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	chuansheng.liu@...el.com
Subject: Re: Please don't replace numeric parameter like 0444 with macro

On Tue, Aug 02, 2016 at 04:58:29PM -0400, Linus Torvalds wrote:
> [ So I answered similarly to another patch, but I'll just re-iterate
> and change the subject line so that it stands out a bit from the
> millions of actual patches ]
> 
> On Tue, Aug 2, 2016 at 1:42 PM, Pavel Machek <pavel@....cz> wrote:
> >
> > Everyone knows what 0644 is, but noone can read S_IRUSR | S_IWUSR |
> > S_IRCRP | S_IROTH (*). Please don't do this.
> 
> Absolutely. It's *much* easier to parse and understand the octal
> numbers, while the symbolic macro names are just random line noise and
> hard as hell to understand. You really have to think about it.
> 
> So we should rather go the other way: convert existing bad symbolic
> permission bit macro use to just use the octal numbers.
> 
> The symbolic names are good for the *other* bits (ie sticky bit, and
> the inode mode _type_ numbers etc), but for the permission bits, the
> symbolic names are just insane crap. Nobody sane should ever use them.
> Not in the kernel, not in user space.

Except that you are inviting the mixes like S_IFDIR | 17 /* oops, should've
been 017, or do we spell it 0017? */ that way.  I certainly agree that this
patch series had been a huge pile of manure, but "let's convert it in other
direction" is inviting pretty much the same thing, with lovely potential for
typos, etc.