[PATCH] synchronize_irq needs a barrier

[Benjamin Herrenschmidt]

 .../...

> This patch (mostly written by Linus) fixes this by using spin
> > locks instead of memory barries on the synchronize_irq() path.
> > 
> > Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
> 
> Good for me.
> 
> Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

Hrm... not on yet. Herbert, care to resend, looks like it fell down the
wrong hole in Linus mailbox :-)

Cheers,
Ben.