Hi Paul, On Tue, Jul 14, 2015 at 01:45:40PM +0100, Paul E. McKenney wrote: > On Tue, Jul 14, 2015 at 11:04:29AM +0100, Will Deacon wrote: > > Given that RCU is currently the only user of this barrier, how would you > > feel about making the barrier local to RCU and not part of the general > > memory-barrier API? > > In theory, no objection. Your thought is to leave the definitions where > they are, mark them as being used only by RCU, and removing mention from > memory-barriers.txt? Or did you have something else in mind? Actually, I was thinking of defining them in an RCU header file with an #ifdef CONFIG_POWERPC for the smb_mb() version. Then you could have a big comment describing the semantics, or put that in an RCU Documentation file instead of memory-barriers.txt. That *should* then mean we notice anybody else trying to use the barrier, because they'd need to send patches to either add something equivalent or move the definition out again. > > My main reason for proposing its removal is because I don't want to see > > it being used (incorrectly) all over the place to order the new RELEASE > > and ACQUIRE operations I posted separately, at which point we have to try > > fixing up all the callers or retrofitting some semantics. It doesn't help > > that memory-barriers.txt lumps things like LOCK and ACQUIRE together, > > whereas this barrier is currently only intended to be used in conjunction > > with the former. > > Heh! That lumping was considered to be a feature at the time. ;-) Oh, I'm sure it was added with good intentions! Will -- 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
