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Date: Wed, 19 Jan 2005 09:04:03 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Peter Chubb <peterc@gelato.unsw.edu.au>
Cc: Tony Luck <tony.luck@intel.com>, Darren Williams <dsw@gelato.unsw.edu.au>,
       Andrew Morton <akpm@osdl.org>, Chris Wedgwood <cw@f00f.org>,
       torvalds@osdl.org, benh@kernel.crashing.org,
       linux-kernel@vger.kernel.org, Ia64 Linux <linux-ia64@vger.kernel.org>,
       Christoph Hellwig <hch@infradead.org>
Subject: Re: Horrible regression with -CURRENT from "Don't busy-lock-loop in preemptable spinlocks" patch
Message-ID: <20050119080403.GB29037@elte.hu>
References: <20050117055044.GA3514@taniwha.stupidest.org> <20050116230922.7274f9a2.akpm@osdl.org> <20050117143301.GA10341@elte.hu> <20050118014752.GA14709@cse.unsw.EDU.AU> <16877.42598.336096.561224@wombat.chubb.wattle.id.au>
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* Peter Chubb <peterc@gelato.unsw.edu.au> wrote:

> Here's a patch that adds the missing read_is_locked() and
> write_is_locked() macros for IA64.  When combined with Ingo's patch, I
> can boot an SMP kernel with CONFIG_PREEMPT on.
> 
> However, I feel these macros are misnamed: read_is_locked() returns
> true if the lock is held for writing; write_is_locked() returns true
> if the lock is held for reading or writing.

well, 'read_is_locked()' means: "will a read_lock() succeed" [assuming
no races]. Should name it read_trylock_test()/write_trylock_test()
perhaps?

	Ingo