Re: Linux 2.6.32-rc1

Ingo Molnar
2009-09-30T20:22:53Z

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Wed, 30 Sep 2009, Eric Dumazet wrote:
> > > +#define cmpxchg64(ptr, o, n) \
> > > +({ \
> > > + __typeof__(*(ptr)) __ret; \
> > > + __typeof__(*(ptr)) __old = (o); \
> > > + __typeof__(*(ptr)) __new = (n); \
> > > + alternative_io("call cmpxchg8b_emu", \
> > > + "lock; cmpxchg8b (%%esi)" , \
> > > + X86_FEATURE_CX8, \
> > > + "=A" (__ret), \
> > > + "S" ((ptr)), "0" (__old), \
> > > + "b" ((unsigned int)__new), \
> > > + "c" ((unsigned int)(__new>>32))); \
> >
> > probably a "memory" clobber is needed, alternative_io() doesnt provide it.
>
> Yeah, good catch.

Yeah - i'm testing this right now, it looks like something that could
explain the hang.

Ingo