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Date: Mon, 17 Jan 2005 18:50:57 +1100
From: Paul Mackerras <paulus@samba.org>
To: Chris Wedgwood <cw@f00f.org>
Cc: Andrew Morton <akpm@osdl.org>, torvalds@osdl.org, mingo@elte.hu,
       benh@kernel.crashing.org, linux-kernel@vger.kernel.org
Subject: Re: Horrible regression with -CURRENT from "Don't busy-lock-loop in preemptable spinlocks" patch
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Chris Wedgwood writes:

> +#define rwlock_is_write_locked(x) ((x)->lock == 0)

AFAICS on i386 the lock word, although it goes to 0 when write-locked,
can then go negative temporarily when another cpu tries to get a read
or write lock.  So I think this should be

((signed int)(x)->lock <= 0)

(or the equivalent using atomic_read).

Paul.