On Fri, Jul 10, 2015 at 04:30:46AM +0000, Vineet Gupta wrote: > > Since we are on the topic, the cmpxchg() loop in arch/arc/kernel/smp.c still > irritates me. > Do we need a new set of primitives to operate atomically on non atomic_t data or > does that mean that the data *not* being atomic_t but requiring such semantics is > the fundamental problem and thus needs to be converted first. So if you look at the last patch, there's already a few sites that do things like: + atomic_or(*mask, (atomic_t *)&flushcache_cpumask); Which is of course ugly as hell, but does work. Esp. inside arch code. Now the 'problem' with cmpxchg/xchg, the instructions working on !atomic data is: http://lkml.kernel.org/r/alpine.LRH.2.02.1406011342470.20831@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx http://lkml.kernel.org/r/20140606175316.GV13930@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx And note that includes some arc. Adding more such primitives will only make it harder on those already 'broken' archs. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
