linux-kernel - Re: Mark bitrevX() functions as const

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: <15033.1165842882@redhat.com>
Date:	Mon, 11 Dec 2006 13:14:42 +0000
From:	David Howells <dhowells@...hat.com>
To:	Jeff Garzik <jeff@...zik.org>
Cc:	David Howells <dhowells@...hat.com>,
	Akinobu Mita <akinobu.mita@...il.com>, torvalds@...l.org,
	akpm@...l.org, linux-kernel@...r.kernel.org,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: Mark bitrevX() functions as const 

Jeff Garzik <jeff@...zik.org> wrote:

> * overall, I agree with this type of change.  several Linux lib functions
> could use this sort of annotation.

Yes.  I just happened to notice bitrev.c at the end of my git pull and wondered
if it was what it sounded like...

> * I question its usefulness on static [inline] functions, because the compiler
> should be able to figure out side effects.  have you examined before-and-after
> asm to see if the code generation changes for the inlined area?

It doesn't actually make any difference, but I think such functions should be
so marked anyway: it gives both the code writer and the compiler more
information (though they're both free to ignore it if they like).

> * naked __attribute__ is ugly.  define something short and memorable in
> include/linux/compiler.h.

I'm not sure that's a good idea.  You have to be careful not to cause confusion
with ordinary "const".

> * another annotation to consider is C99 keyword 'restrict'.

Indeed, though I presume you don't mean in this particular case...

David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/