Re: x86 arch updates also broke s390

Ingo Molnar
2008-02-01T10:03:11Z

* Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> On Fri, 2008-02-01 at 10:48 +0100, Ingo Molnar wrote:
> > > Defining GENERIC_LOCKBREAK in arch/s390/Kconfig takes care of it.
> > I'll
> > > cook up a patch and queue it in git390.
> >
> > the one below should do the trick.
>
> Thanks but I already queued a different one (see below). The other
> architectures that define GENERIC_LOCKBREAK have the "depends on SMP
> && PREEMPT" line as well. The line does make sense if you look at the
> way how spin_is_contended is used, no ?

yes, you are right and your fix is the correct one. Currently, if we
define GENERIC_LOCKBREAK on UP then we get accesses to the non-existing
lock->need_lockbreak field.

[ btw., this is really a small uncleanliness in the generic code: it
should be possible for an architecture to just enable
GENERIC_LOCKBREAK unconditionally, to indicate that it intends to "let
the generic code do this". Then the generic code, when it does not
have a field (such as on UP), should just not access it. But this is a
small detail. ]

Ingo