From: Andrea Arcangeli <andrea@suse.de>
To: Andrew Morton <akpm@digeo.com>
Cc: "David S. Miller" <davem@redhat.com>,
shemminger@osdl.org, rmk@arm.linux.org.uk, ak@muc.de,
davidm@napali.hpl.hp.com, anton@samba.org, linux-mm@kvack.org
Subject: Re: Linus rollup
Date: Thu, 30 Jan 2003 02:35:22 +0100 [thread overview]
Message-ID: <20030130013522.GP1237@dualathlon.random> (raw)
In-Reply-To: <20030129172743.1e11d566.akpm@digeo.com>
On Wed, Jan 29, 2003 at 05:27:43PM -0800, Andrew Morton wrote:
> @@ -82,11 +85,12 @@ static inline int fr_write_trylock(frloc
>
> if (ret) {
> ++rw->pre_sequence;
> - wmb();
> + mb();
> }
this isn't needed
if we hold the spinlock, the serialized memory can't be change under us,
so there's no need to put a read barrier, we only care that pre_sequence
is visible before the chagnes are visible and before post_sequence is
visible, hence only wmb() (after spin_lock and pre_sequence++) is
needed there and only rmb() is needed in the read-side.
Andrea
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next prev parent reply other threads:[~2003-01-30 1:35 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-29 6:07 Andrew Morton
2003-01-29 6:53 ` David Mosberger
2003-01-29 7:25 ` David S. Miller
2003-01-29 9:33 ` Andrew Morton
2003-01-29 9:35 ` David S. Miller
2003-01-29 9:54 ` Anton Blanchard
2003-01-29 9:59 ` Russell King
2003-01-29 9:51 ` David S. Miller
2003-01-29 10:26 ` Andrew Morton
2003-01-29 22:35 ` Stephen Hemminger
2003-01-29 23:12 ` Andrew Morton
2003-01-30 0:30 ` David S. Miller
2003-01-30 1:27 ` Andrew Morton
2003-01-30 1:24 ` Andi Kleen
2003-01-30 2:01 ` Andrew Morton
2003-01-30 1:35 ` Andrea Arcangeli [this message]
2003-01-30 2:00 ` Andrew Morton
2003-01-30 1:50 ` Jeff Garzik
2003-01-30 2:03 ` Andrea Arcangeli
2003-01-30 17:09 ` Stephen Hemminger
2003-01-30 17:15 ` Randy.Dunlap
2003-01-30 17:25 ` Andi Kleen
2003-01-30 17:23 ` Randy.Dunlap
2003-01-30 1:52 ` Richard Henderson
2003-01-30 2:06 ` Andrea Arcangeli
2003-01-30 1:54 ` Andrea Arcangeli
2003-01-30 2:19 ` Andrew Morton
2003-01-30 17:37 ` Stephen Hemminger
2003-01-30 17:50 ` Andrea Arcangeli
2003-01-30 2:00 ` Richard Henderson
2003-01-30 0:46 ` Andrea Arcangeli
2003-01-30 0:43 ` Andrea Arcangeli
2003-01-29 10:16 ` Andrew Morton
2003-01-29 17:04 ` David Mosberger
2003-01-29 17:25 ` Russell King
2003-01-29 19:05 ` David Mosberger
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