Using __kuser_cmpxchg

Fri Nov 16 00:25:00 GMT 2007

> > > In the mean time you can work around it by using a mutex around the
> > > thread state modification instead of using cmpxchg on it. Or if your
> > > platform is ARMv6 or higher then you won't get those spurious false
> > > negatives.
> >
> > Ah, OK, that's interesting: it sounds like you understand under what
> > circumstances it may fail "spuriously".
>> Heh, I wrote that code (and comment). :-)
>> > What are these?
>> On a pre-ARMv6 processor

Similar "spurious" failures can happen on ARMv6 processors.
ARMv6 cpus don't have atomic operations either. They have ldrex/strex, where 
the latter will fail if another CPU modifies the memory *or* a context switch 
occurs.
Paul