linux-kernel - Re: [PATCH] Documentation: Fix incorrect paths/magic in magic numbers rst

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Message-ID: <87jzdi7oa7.fsf@trenco.lwn.net>
Date: Mon, 04 Nov 2024 13:10:56 -0700
From: Jonathan Corbet <corbet@....net>
To: Nir Lichtman <nir@...htman.org>
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Documentation: Fix incorrect paths/magic in magic
 numbers rst

Nir Lichtman <nir@...htman.org> writes:

> On Mon, Nov 04, 2024 at 12:35:30PM -0700, Jonathan Corbet wrote:
>> Nir Lichtman <nir@...htman.org> writes:
>> 
>> > Fix some no longer true header/c file paths and correct the BAYCOM_MAGIC
>> > value to be decimal as in the source instead of incorrectly hexadecimal
>> >
>> > Signed-off-by: Nir Lichtman <nir@...htman.org>
>> > ---
>> >  Documentation/staging/magic-number.rst | 6 +++---
>> >  1 file changed, 3 insertions(+), 3 deletions(-)
>> 
>> I've applied this, thanks.  I do continue to wonder about the value of
>> this file in general, though...
>
> Agreed, it feels pretty much like abandoned book keeping that gives minimal
> value since the chance of magics colliding is slim, but I think the general tip
> before the table of magics is pretty good.
>
> What is your opinion about integrating the tip in a different page and deleting
> this page entirely?

Well, that's part of my reasoning, actually.  I assume you're talking
about this:

> It is a **very** good idea to protect kernel data structures with magic
> numbers.  This allows you to check at run time whether (a) a structure
> has been clobbered, or (b) you've passed the wrong structure to a
> routine. 

The thing is, that's really not a guideline that anybody has followed
for many years.  I dug into this a while back:

  https://lwn.net/Articles/915163/

There was a series to remove all of this cruft a couple of years ago
that the author eventually gave up on:

  https://lore.kernel.org/lkml/cover.1668128257.git.nabijaczleweli@nabijaczleweli.xyz/

Honestly, I think the best thing to do is to simply remove the file.

Thanks,

jon