LDREX/STREX and pre-emption on SMP hardware

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Sep 14 10:21:48 EDT 2009

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.

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