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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "David S. Miller" <davem@redhat.com>
Cc: Willy Tarreau <willy@w.ods.org>,
	jamie@shareable.org, albert@users.sourceforge.net,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	chip@pobox.com
Subject: Re: [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers
Date: 09 Aug 2003 11:42:54 +0100	[thread overview]
Message-ID: <1060425774.4933.73.camel@dhcp22.swansea.linux.org.uk> (raw)
In-Reply-To: <20030809015142.56190015.davem@redhat.com>

On Sad, 2003-08-09 at 09:51, David S. Miller wrote:
> I believe the C language allows for systems where the NULL pointer is
> not zero.

Its a fudge for some systems. However NULL == 0 is always true.

> I can't think of any reason why the NULL macro exists otherwise.

<OldFart>
NULL is really important in K&R C because you don't have prototypes and
sizeof(foo *) may not be the same as sizeof(int). This leads to very
nasty problems that people nowdays forget about.
</OldFart>



  parent reply	other threads:[~2003-08-09 10:46 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-05 12:44 [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers Albert Cahalan
2003-08-09  0:21 ` Jamie Lokier
2003-08-09  8:13   ` Willy Tarreau
2003-08-09  8:51     ` David S. Miller
2003-08-09  9:36       ` Jamie Lokier
2003-08-09 10:10       ` Herbert Xu
2003-08-09 10:42       ` Alan Cox [this message]
2003-08-09 16:23         ` Jamie Lokier
2003-08-09 17:30           ` NULL. Again. (was Re: [PATCH] 2.4.22pre10: {,un}likely_p()) Chip Salzenberg
2003-08-09 17:43             ` Sean Neakums
2003-08-11  1:04               ` Jamie Lokier
2003-08-11 23:06               ` Timothy Miller
2003-08-09 19:44             ` Jamie Lokier
  -- strict thread matches above, loose matches on Subject: below --
2003-08-10  4:03 [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers Albert Cahalan
2003-08-10  7:29 ` Willy Tarreau
2003-08-10  8:02   ` Willy Tarreau
2003-08-11  1:23   ` Chip Salzenberg
2003-08-11  2:09     ` Jamie Lokier
2003-08-11  2:39       ` Chip Salzenberg
2003-08-11  4:02         ` Albert Cahalan
2003-08-11  4:30         ` Jamie Lokier
2003-08-11  5:30         ` Willy Tarreau
2003-08-11  5:42           ` Jamie Lokier
2003-08-11 13:09             ` Albert Cahalan
2003-08-11 18:55               ` Andrew Morton
2003-08-11 23:13                 ` Albert Cahalan
2003-08-13 19:42                   ` Jamie Lokier
2003-08-11  4:55   ` Jamie Lokier
2003-08-11  5:26     ` Willy Tarreau
2003-08-11  5:38       ` Jamie Lokier
2003-08-04 17:06 Chip Salzenberg

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