From: Linus Torvalds <torvalds@osdl.org>
To: Peter Chubb <peterc@gelato.unsw.edu.au>
Cc: Chris Wedgwood <cw@f00f.org>, Andrew Morton <akpm@osdl.org>,
paulus@samba.org, linux-kernel@vger.kernel.org, mingo@elte.hu,
tony.luck@intel.com, dsw@gelato.unsw.edu.au,
benh@kernel.crashing.org, linux-ia64@vger.kernel.org,
hch@infradead.org, wli@holomorphy.com, jbarnes@sgi.com
Subject: Re: [PATCH RFC] 'spinlock/rwlock fixes' V3 [1/1]
Date: Thu, 20 Jan 2005 07:51:08 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.58.0501200747230.8178@ppc970.osdl.org> (raw)
In-Reply-To: <16879.29449.734172.893834@wombat.chubb.wattle.id.au>
On Thu, 20 Jan 2005, Peter Chubb wrote:
>
> I suggest reversing the sense of the macros, and having read_can_lock()
> and write_can_lock()
>
> Meaning:
> read_can_lock() --- a read_lock() would have succeeded
> write_can_lock() --- a write_lock() would have succeeded.
Yes. This has the advantage of being readable, and the "sense" of the test
always being obvious.
We have a sense problem with the "trylock()" cases - some return "it was
locked" (semaphores), and some return "I succeeded" (spinlocks), so not
only is the sense not immediately obvious from the usage, it's actually
_different_ for semaphores and for spinlocks.
So I like "read_can_lock()", since it's also obvious what it returns.
(And yes, we should fix the semaphore trylock return code, dammit.)
Linus
next prev parent reply other threads:[~2005-01-20 15:55 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
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 [this message]
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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