LDREX/STREX and pre-emption on SMP hardware

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:

quoted

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.