On Fri, Dec 11, 2015 at 01:33:14PM +0000, Will Deacon wrote: > On Fri, Dec 11, 2015 at 01:26:47PM +0100, Peter Zijlstra wrote:
> > While we're there, the acquire in osq_wait_next() seems somewhat ill > > documented too. > > > > I _think_ we need ACQUIRE semantics there because we want to strictly > > order the lock-unqueue A,B,C steps and we get that with: > > > > A: SC > > B: ACQ > > C: Relaxed > > > > Similarly for unlock we want the WRITE_ONCE to happen after > > osq_wait_next, but in that case we can even rely on the control > > dependency there. > > Even for the lock-unqueue case, isn't B->C ordered by a control dependency > because C consists only of stores? Hmm, indeed. So we could go fully relaxed on it I suppose, since the same is true for the unlock site. -- 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/
