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
Date: Mon, 17 Jan 2005 18:50:57 +1100 [thread overview]
Message-ID: <16875.28257.239324.486966@cargo.ozlabs.ibm.com> (raw)
In-Reply-To: <20050117073345.GA3616@taniwha.stupidest.org>
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.
next prev parent reply other threads:[~2005-01-17 7:51 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-17 5:50 Horrible regression with -CURRENT from "Don't busy-lock-loop in preemptable spinlocks" patch Chris Wedgwood
2005-01-17 7:09 ` Andrew Morton
2005-01-17 7:33 ` Chris Wedgwood
2005-01-17 7:50 ` Paul Mackerras [this message]
2005-01-17 8:00 ` Chris Wedgwood
2005-01-17 14:33 ` Ingo Molnar
2005-01-18 1:47 ` Darren Williams
2005-01-18 4:28 ` Darren Williams
2005-01-18 7:08 ` Chris Wedgwood
2005-01-19 0:14 ` Peter Chubb
2005-01-19 8:04 ` Ingo Molnar
2005-01-19 9:18 ` Peter Chubb
2005-01-19 9:20 ` Ingo Molnar
2005-01-19 21:43 ` Paul Mackerras
2005-01-20 2:34 ` [PATCH RFC] 'spinlock/rwlock fixes' V3 [1/1] Chris Wedgwood
2005-01-20 3:01 ` Andrew Morton
2005-01-20 3:18 ` Chris Wedgwood
2005-01-20 3:33 ` Andrew Morton
2005-01-20 8:59 ` Peter Chubb
2005-01-20 13:04 ` Ingo Molnar
2005-01-20 15:51 ` Linus Torvalds
2005-01-20 16:08 ` [patch 1/3] spinlock fix #1, *_can_lock() primitives Ingo Molnar
2005-01-20 16:11 ` [patch 2/3] spinlock fix #2: generalize [spin|rw]lock yielding Ingo Molnar
2005-01-20 16:12 ` [patch 3/3] spinlock fix #3: type-checking spinlock primitives, x86 Ingo Molnar
2005-01-20 16:14 ` [patch] stricter type-checking rwlock " Ingo Molnar
2005-01-20 16:16 ` [patch] minor spinlock cleanups Ingo Molnar
2005-01-20 16:31 ` [patch 1/3] spinlock fix #1, *_can_lock() primitives Linus Torvalds
2005-01-20 16:40 ` Ingo Molnar
2005-01-20 17:48 ` Linus Torvalds
2005-01-20 17:53 ` Ingo Molnar
2005-01-20 18:22 ` [patch, BK-curr] nonintrusive spin-polling loop in kernel/spinlock.c Ingo Molnar
2005-01-20 18:25 ` [patch, BK-curr] rename 'lock' to 'slock' in asm-i386/spinlock.h Ingo Molnar
2005-01-20 23:45 ` [patch, BK-curr] nonintrusive spin-polling loop in kernel/spinlock.c Linus Torvalds
2005-01-20 16:44 ` [patch 1/3] spinlock fix #1, *_can_lock() primitives Ingo Molnar
2005-01-20 16:59 ` Ingo Molnar
2005-01-20 16:47 ` Ingo Molnar
2005-01-20 16:57 ` Ingo Molnar
2005-01-20 16:05 ` [PATCH RFC] 'spinlock/rwlock fixes' V3 [1/1] Linus Torvalds
2005-01-20 16:20 ` Ingo Molnar
2005-01-20 16:18 ` Linus Torvalds
2005-01-20 16:23 ` Ingo Molnar
2005-01-20 17:30 ` Linus Torvalds
2005-01-20 17:38 ` Ingo Molnar
2005-01-20 16:28 ` Ingo Molnar
2005-01-20 5:49 ` Horrible regression with -CURRENT from "Don't busy-lock-loop in preemptable spinlocks" patch Grant Grundler
2005-01-17 7:38 ` [PATCH] __get_cpu_var should use __smp_processor_id() not smp_processor_id() Chris Wedgwood
2005-01-17 14:40 ` Ingo Molnar
2005-01-17 18:53 ` Chris Wedgwood
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