On 01/13, Will Deacon wrote: > > 1. Does smp_mb__before_spinlock actually have to order prior loads > against later loads and stores? Documentation/memory-barriers.txt > says it does, but that doesn't match the comment
The comment says that smp_mb__before_spinlock() + spin_lock() should only serialize STOREs with LOADs. This is because it was added to ensure that the setting of condition can't race with ->state check in ttwu(). But since we use wmb() it obviously serializes STOREs with STORES. I do not know if this should be documented, but we already have another user which seems to rely on this fact: set_tlb_flush_pending(). As for "prior loads", this doesn't look true... Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
