On Fri, 31 Mar 2006, Chen, Kenneth W wrote: > > They are not. They provide equivalent barrier when performed > > before/after a clear_bit, there is a big difference. > > Just to give another blunt brutal example, what is said here is equivalent > to say kernel requires: > > <end of critical section> > smp_mb_before_spin_unlock > spin_unlock > > Because it is undesirable to have spin_unlock to leak into the critical > Section and allow critical section to leak after spin_unlock. This is > just plain brain dead. I think we could say that lock semantics are different from barriers. They are more like acquire and release on IA64. The problem with smb_mb_*** is that the coder *explicitly* requested a barrier operation and we do not give it to him. - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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