On 12/19/2013 10:09 AM, H. Peter Anvin wrote: > On 12/19/2013 09:07 AM, Ingo Molnar wrote: >> >> Likewise, having a barrier before the MONITOR looks sensible as well. >> Having it _after_ monitor looks weird and is probably wrong. [It might >> have been the effects of someone seeing the spurious wakeup problems >> with realizing the true source, or so.] >> > > Does anyone know the history of this barrier after the monitor? I know > Len is looking for a minimal patchset that can go into -stable, and it > seems prudent to not preturb the code more than necessary, but going > forward it would be nice to know... > Hmm... it *looks* like it is intended to be part of the construct: smp_mb(); if (!need_resched()) ... I found a note in the HLT variant of the function saying: /* * TS_POLLING-cleared state must be visible before we * test NEED_RESCHED: */ ... which presumably has been copied elsewhere. -hpa -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html