On Thu, 19 Aug 2010, Ian Campbell wrote:
> On Thu, 2010-08-19 at 11:50 +0100, Ian Campbell wrote:
> > On Thu, 2010-08-19 at 11:37 +0100, Stefano Stabellini wrote:
> > > On Thu, 19 Aug 2010, Ian Campbell wrote:
> > > > if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
> > > > + (xen_emul_unplug != -1) &&
> > > > (xen_emul_unplug & XEN_UNPLUG_IGNORE)))
> > >
> > > I wouldn't add xen_emul_unplug != -1 because it should be clear that
> > > xen_emul_unplug & XEN_UNPLUG_IGNORE always implies xen_emul_unplug != -1.
> >
> > That's not correct since -1 is all 1s. So you can get a false positive
> > for "xen_emul_unplug & XEN_UNPLUG_IGNORE" if xen_emul_unplug == -1.
>
> IOW if we were to rewrite the test to use less boolean logic the patch
> might look like:
>
> if (r) {
> if (r != XEN_PLATFORM_ERR_MAGIC)
> return;
> + if (xen_emul_unplug == -1)
> + return;
> if (!(xen_emul_unplug & XEN_UNPLUG_IGNORE))
> return;
> }
>
> Perhaps this refactoring is worthwhile in any case? It certainly makes
> my head hurt less ;-)
>
Yeah, it is probably worth it anyway :)
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