linux-kernel - Re: [PATCH] mm/page_alloc: fix documentation error and remove magic numbers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200624140958.GN21350@casper.infradead.org>
Date:   Wed, 24 Jun 2020 15:09:58 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Rafael Aquini <aquini@...hat.com>
Cc:     Joel Savitz <jsavitz@...hat.com>, linux-kernel@...r.kernel.org,
        Vlastimil Babka <vbabka@...e.cz>,
        John Hubbard <jhubbard@...dia.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Subject: Re: [PATCH] mm/page_alloc: fix documentation error and remove magic
 numbers

On Wed, Jun 24, 2020 at 10:07:27AM -0400, Rafael Aquini wrote:
> On Wed, Jun 24, 2020 at 12:12:55PM +0100, Matthew Wilcox wrote:
> > On Tue, Jun 23, 2020 at 11:27:12PM -0400, Joel Savitz wrote:
> > > In addition, this patch replaces the magic number bounds with symbolic
> > > constants to clarify the logic.
> > 
> > Why do people think this kind of thing makes the code easier to read?
> > It actually makes it harder.  Unless the constants are used in more
> > than one place, just leave the numbers where they are.
> > 
> > > @@ -7852,6 +7852,9 @@ void setup_per_zone_wmarks(void)
> > >   * 8192MB:	11584k
> > >   * 16384MB:	16384k
> > >   */
> > > +static const int MIN_FREE_KBYTES_LOWER_BOUND = 1 << 7;
> > > +static const int MIN_FREE_KBYTES_UPPER_BOUND = 1 << 18;
> > > +
> 
> I think these constants would look better if declared as an enum.

Why does having to look in two different places make the code clearer?