On Tue, 17 Jun 2014, Tejun Heo wrote:
> * Add data dependency barrier to percpu accessors and write barrier to > the allocator with the comment that this will be replaced with > proper assignment macros and mark this change w/ -stable. > > * Later, introduce percpu pointer assignment macros and convert all > users and remove the wmb added above. Uhhh no. The percpu stuff and the associated per cpu atomics are to be used for stuff that is per cpu specific and runs at the fastest speed doable at that level. Introducing implicit barriers is not that good an idea. The concurrency guarantees for the per cpu operations are related to being interrupted or rescheduled but not for accesses from other processors. Cpus maintain at least the appearance of operations being visible in sequence for code running on the same processor. Therefore no barriers are needed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
