Re: Linux 2.6.32-rc1

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> * Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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.

Yeah - that was the cause of the hang.

I've pushed out the updated patches - they should show up in this thread 
soon. I also updated the emulation implementation to your simpler 
variant. (will test that too)

	Ingo
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