From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Mon, 14 Sep 2009 15:21:48 +0100
Subject: LDREX/STREX and pre-emption on SMP hardware
In-Reply-To: <20090914140908.GD21580@n2100.arm.linux.org.uk>
References: <1250890146.29685.18.camel@david-laptop>
	<1251128692.28977.17.camel@pc1117.cambridge.arm.com>
	<1251134043.31975.23.camel@david-laptop>
	<1251135709.28977.40.camel@pc1117.cambridge.arm.com>
	<20090914014353.GA4762@shareable.org>
	<20090914100056.GC16644@n2100.arm.linux.org.uk>
	<1252922773.16853.62.camel@pc1117.cambridge.arm.com>
	<1252928832.16853.96.camel@pc1117.cambridge.arm.com>
	<1252930881.16853.99.camel@pc1117.cambridge.arm.com>
	<20090914140908.GD21580@n2100.arm.linux.org.uk>
Message-ID: <20090914142148.GE21580@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Sep 14, 2009 at 03:09:09PM +0100, Russell King - ARM Linux wrote:
> On Mon, Sep 14, 2009 at 01:21:21PM +0100, Catalin Marinas wrote:
> > And here's an untested patch to clear the exclusive monitor on the
> > exception return path. If you are OK with the idea, I'll do some testing
> > before pushing it for upstream:
> 
> However, a plain STR is not guaranteed to change the state of the
> exclusive monitor - it is implementation defined whether STR does
> or not.
> 
> This is true for both the local and global exclusive monitors.

... only for the same local CPU.  A STR done by another CPU to the
address being monitored clears the global monitor.