From: kaih@khms.westfalen.de (Kai Henningsen)
To: linux-kernel@vger.kernel.org
Subject: Re: page_launder() bug
Date: 08 May 2001 19:59:00 +0200 [thread overview]
Message-ID: <80VZCMhHw-B@khms.westfalen.de> (raw)
In-Reply-To: <200105071452.f47Eq2jn008611@pincoya.inf.utfsm.cl>
In-Reply-To: <davem@redhat.com> <15094.10942.592911.70443@pizda.ninka.net> <200105071452.f47Eq2jn008611@pincoya.inf.utfsm.cl>
vonbrand@inf.utfsm.cl (Horst von Brand) wrote on 07.05.01 in <200105071452.f47Eq2jn008611@pincoya.inf.utfsm.cl>:
> "David S. Miller" <davem@redhat.com> said:
> > Jonathan Morton writes:
> > > >- page_count(page) == (1 + !!page->buffers));
> > >
> > > Two inversions in a row?
> >
> > It is the most straightforward way to make a '1' or '0'
> > integer from the NULL state of a pointer.
>
> IMVHO, it is clearer to write:
>
> page_count(page) == 1 + (page->buffers != NULL)
>
> At least, the original poster wouldn't have wondered, and I wouldn't have
> had to think a bit to find out what it meant... If gcc generates worse code
> for this, it should be fixed.
Huh. IMO, that is significantly *less* readable. And incidentally I'd be
less certain that it actually does what you want - it is rather easy to
convince yourself that !! has to do the right thing.
MfG Kai
next prev parent reply other threads:[~2001-05-08 18:20 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-05-06 21:08 page_launder() bug BERECZ Szabolcs
2001-05-06 21:59 ` Jonathan Morton
2001-05-06 22:07 ` BERECZ Szabolcs
2001-05-07 4:55 ` David S. Miller
2001-05-07 5:19 ` Aaron Lehmann
2001-05-07 6:26 ` Tobias Ringstrom
2001-05-07 8:59 ` Helge Hafting
2001-05-07 19:02 ` J . A . Magallon
2001-05-08 7:52 ` Helge Hafting
2001-05-10 12:19 ` Ingo Oeser
2001-05-10 10:51 ` Anuradha Ratnaweera
2001-05-07 10:52 ` Alan Cox
2001-05-07 13:49 ` Daniel Phillips
2001-05-07 13:53 ` H. Peter Anvin
2001-05-07 8:54 ` David S. Miller
2001-05-07 15:12 ` Tobias Ringstrom
2001-05-07 14:52 ` Horst von Brand
[not found] ` <davem@redhat.com>
2001-11-21 7:16 ` [VM/MEMORY-SICKNESS] 2.4.15-pre7 kmem_cache_create invalid opcode Jeff V. Merkey
2001-11-21 6:22 ` David S. Miller
2001-11-21 6:47 ` David S. Miller
2001-11-21 6:54 ` Jeff Merkey
2001-11-21 6:56 ` David S. Miller
2001-11-21 7:03 ` Jeff Merkey
2001-11-21 7:49 ` arjan
2001-11-21 18:31 ` Jeff Merkey
2001-11-21 19:06 ` Doug Ledford
2001-11-21 19:51 ` Jeff Merkey
2001-11-21 19:58 ` J Sloan
2001-11-21 20:38 ` Doug Ledford
2001-11-21 21:17 ` Jeff Merkey
2001-11-21 19:16 ` Arjan van de Ven
2001-11-21 19:53 ` Jeff Merkey
2001-11-21 20:36 ` Doug Ledford
2001-11-21 21:16 ` Jeff Merkey
2001-11-21 21:28 ` Robert Love
2001-11-21 7:09 ` David S. Miller
2001-11-21 7:14 ` Jeff Merkey
2001-11-21 7:28 ` Stuart Young
2001-11-21 7:33 ` Jeff V. Merkey
2001-11-21 6:54 ` Chris Abbey
2001-11-21 7:05 ` Jeff Merkey
2001-11-21 6:47 ` Kai Henningsen
2001-11-21 18:28 ` Jeff Merkey
2001-11-21 8:49 ` Alan Cox
2001-11-21 18:28 ` Jeff Merkey
2001-05-08 17:59 ` Kai Henningsen [this message]
2001-05-09 2:32 ` page_launder() bug Rusty Russell
2001-05-09 8:43 ` Martin Dalecki
2001-05-09 3:36 ` Jonathan Morton
2001-05-07 17:59 ` Linus Torvalds
2001-05-07 21:22 ` Marcelo Tosatti
2001-05-07 23:23 ` Linus Torvalds
2001-05-07 21:50 ` Marcelo Tosatti
2001-05-07 23:52 ` Linus Torvalds
2001-05-07 22:26 ` Marcelo Tosatti
2001-05-08 2:29 ` Linus Torvalds
2001-05-13 16:08 ` Rik van Riel
2001-05-13 19:29 ` Linus Torvalds
2001-05-14 22:05 ` Marcelo Tosatti
2001-05-08 0:16 ` David S. Miller
2001-05-08 2:34 ` Linus Torvalds
2001-05-08 1:40 ` Marcelo Tosatti
2001-05-08 3:46 ` Linus Torvalds
2001-05-08 2:37 ` Marcelo Tosatti
2001-05-08 21:16 ` Marcelo Tosatti
2001-05-08 23:38 ` Linus Torvalds
2001-05-08 23:53 ` Marcelo Tosatti
2001-05-09 2:13 ` David S. Miller
2001-05-09 17:38 ` Marcelo Tosatti
2001-05-09 20:05 ` David S. Miller
2001-05-09 18:40 ` Marcelo Tosatti
2001-05-09 21:08 ` David S. Miller
2001-05-09 19:50 ` Marcelo Tosatti
2001-05-13 16:34 ` Rik van Riel
2001-05-13 19:34 ` Linus Torvalds
2001-05-13 19:39 ` Rik van Riel
2001-05-13 20:42 ` Linus Torvalds
2001-05-14 7:05 ` Kai Henningsen
2001-05-13 17:52 ` David S. Miller
2001-05-13 17:55 ` Rik van Riel
2001-05-13 18:00 ` David S. Miller
2001-05-08 6:50 ` David S. Miller
2001-05-08 7:40 ` Linus Torvalds
2001-05-08 18:53 ` Marcelo Tosatti
2001-05-08 8:29 ` David S. Miller
2001-05-08 3:22 ` David S. Miller
2001-05-08 3:26 ` Linus Torvalds
2001-05-08 2:47 ` David S. Miller
2001-05-08 1:34 ` Marcelo Tosatti
2001-05-08 3:18 ` David S. Miller
2001-05-08 1:47 ` Marcelo Tosatti
2001-05-08 3:24 ` Linus Torvalds
2001-05-08 3:29 ` David S. Miller
2001-05-08 10:36 ` BERECZ Szabolcs
2001-05-08 12:33 ` Mikulas Patocka
2001-05-13 16:24 ` Rik van Riel
2001-05-13 21:02 ` Another VM race? (was: page_launder() bug) Mikulas Patocka
2001-05-13 23:04 ` Rik van Riel
2001-05-14 9:53 ` Mikulas Patocka
2001-05-08 0:06 ` page_launder() bug David S. Miller
2001-05-07 23:31 ` David S. Miller
2001-05-07 22:44 ` David S. Miller
2001-05-08 1:00 ` Horst von Brand
2001-05-07 0:32 Jonathan Lundell
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