From: Rusty Russell <rusty@rustcorp.com.au>
To: torvalds@transmeta.com (Linus Torvalds)
Cc: linux-kernel@vger.kernel.org
Subject: Re: [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion
Date: Fri, 12 Oct 2001 15:06:06 +1000 [thread overview]
Message-ID: <20011012150606.5d522fda.rusty@rustcorp.com.au> (raw)
In-Reply-To: <9q20a2$2cg$1@penguin.transmeta.com>
In-Reply-To: <OF206EE8AA.7A83A16B-ON88256AE1.005467E3@boulder.ibm.com> <20011010185848.D726@athlon.random> <9q20a2$2cg$1@penguin.transmeta.com>
On Wed, 10 Oct 2001 17:25:22 +0000 (UTC)
torvalds@transmeta.com (Linus Torvalds) wrote:
> Absolutely. It's not that expensive an operation on sane hardware. And
> it's definitely conceptually the only right thing to do - we're saying
> that we're doing a read that depends on a previous read having seen
> previous memory. Ergo, "rmb()".
Accessing pointer contents after you dereference the pointer is "obvious":
we've been trying to get Richard to understand the problem for FIVE MONTHS,
and he's not stupid!
The PPC manual (thanks Paul M) clearly indicates rmbdd() is not neccessary.
That they mention it explicitly suggests it's going to happen on more
architectures: you are correct, we should sprinkle rmbdd() everywhere
(rmb() is heavy on current PPC) and I'll update the Kernel Locking Guide now
the rules have changed.[1]
Rusty.
[1] Aren't we lucky our documentation is so sparse noone can accuse us of being
inconsistent? 8)
next prev parent reply other threads:[~2001-10-12 5:10 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-10-10 15:24 [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion Paul McKenney
2001-10-10 16:58 ` Andrea Arcangeli
2001-10-10 17:25 ` Linus Torvalds
2001-10-12 5:06 ` Rusty Russell [this message]
2001-10-12 16:28 ` Linus Torvalds
2001-10-12 19:50 ` Al Dunsmuir
2001-10-13 1:07 ` Paul Mackerras
2001-10-13 1:54 ` Davide Libenzi
2001-10-13 2:04 ` Linus Torvalds
2001-10-13 2:31 ` Davide Libenzi
2001-10-13 2:46 ` Davide Libenzi
2001-10-13 3:30 ` Linus Torvalds
2001-10-13 2:49 ` Paul Mackerras
2001-10-13 14:11 ` Re: RFC: patch to allow lock-free traversal of lists Paul E. McKenney
2001-10-13 2:00 ` [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion Linus Torvalds
2001-10-13 13:54 ` [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists Alan Cox
2001-10-13 7:38 ` [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion Rusty Russell
2001-10-13 16:28 ` Re: RFC: patch to allow lock-free traversal of lists with insertion ^M Paul E. McKenney
2001-10-13 21:23 ` Rusty Russell
2001-10-12 5:43 ` [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with Albert D. Cahalan
2001-10-12 6:26 ` Paul Mackerras
2001-10-12 8:28 ` Alex Bligh - linux-kernel
2001-10-12 8:51 ` Jonathan Lundell
-- strict thread matches above, loose matches on Subject: below --
2001-10-13 14:42 [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion Paul McKenney
2001-10-13 17:23 ` Linus Torvalds
2001-10-13 17:28 ` Linus Torvalds
2001-10-14 7:25 ` Dipankar Sarma
2001-10-13 18:42 ` Andi Kleen
2001-10-13 19:15 ` Alexander Viro
2001-10-13 20:44 ` Rusty Russell
2001-10-13 21:19 ` Rusty Russell
2001-10-11 10:34 Dipankar Sarma
2001-10-10 21:44 Paul McKenney
2001-10-10 16:00 Paul McKenney
2001-10-10 10:06 Dipankar Sarma
2001-10-10 10:18 ` Linus Torvalds
2001-10-10 11:43 ` Dipankar Sarma
2001-10-12 3:27 ` Rusty Russell
2001-10-12 16:56 ` Linus Torvalds
2001-10-12 18:53 ` Dipankar Sarma
2001-10-13 7:25 ` Rusty Russell
[not found] <20011010182730.0077454b.rusty@rustcorp.com.au>
2001-10-10 9:36 ` Linus Torvalds
2001-10-11 6:50 ` Rusty Russell
2001-10-10 7:58 Dipankar Sarma
2001-10-10 7:06 Dipankar Sarma
2001-10-10 7:21 ` BALBIR SINGH
2001-10-10 9:06 ` Dipankar Sarma
2001-10-10 6:54 Dipankar Sarma
2001-10-10 4:43 Paul McKenney
2001-10-09 15:45 Paul McKenney
2001-10-10 2:05 ` [Lse-tech] " Andrea Arcangeli
2001-10-10 5:05 ` Linus Torvalds
2001-10-10 5:17 ` BALBIR SINGH
2001-10-10 5:29 ` Davide Libenzi
2001-10-10 5:46 ` Linus Torvalds
2001-10-10 6:01 ` BALBIR SINGH
2001-10-10 15:23 ` Victor Yodaiken
2001-10-10 6:16 ` Paul Mackerras
2001-10-10 6:30 ` Linus Torvalds
2001-10-10 7:36 ` Paul Mackerras
2001-10-10 15:54 ` Victor Yodaiken
2001-10-10 21:56 ` Keith Owens
2001-10-10 22:24 ` Victor Yodaiken
2001-10-10 23:46 ` David S. Miller
2001-10-11 0:24 ` Davide Libenzi
2001-10-10 11:54 ` Keith Owens
2001-10-10 13:24 ` Ivan Kokshaysky
2001-10-10 13:41 ` Andrea Arcangeli
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