Rafael J. Wysocki wrote: > On Tuesday, 13 March 2007 11:31, Nick Piggin wrote: > >>Rafael J. Wysocki wrote: >> >>>On Tuesday, 13 March 2007 10:23, Nick Piggin wrote: >>> >> >>>>I wouldn't say that. You're creating an interface here that is going to be >>>>used outside swsusp. Users of that interface may not need locking now, but >>>>that could cause problems down the line. >>> >>> >>>I think we can add the locking when it's necessary. For now, IMHO, it could be >>>confusing to someone who doesn't know the locking is not needed. >> >>I don't know why it would confuse them. We just define the API to >>guarantee the correct locking, and that means the locking _is_ needed. > > > Even if there are no users that actually need the locking and probably never > will be? Probably is the keyword. Why would you *not* make this a sane API? Surely performance isn't the reason? Nor complexity. > For now, register_nosave_region() is to be called by architecture > initialization code _only_ and there's no reason whatsoever why any > architecture would need to call it concurrently from many places. > > >>You don't have to care what the callers are doing. That's the beauty >>of a sane API. > > > Well, I don't think adding unneded infrastructure is a good thing. But defining good APIs is a very good thing. And with my good API, the lock is not unneeded. >>>>But that's because you even use mark_nosave_pages in your implementation. >>>>Mine uses the nosave regions directly. >>> >>> >>>Well, I think we need two bits per page anyway, to mark free pages and >>>pages allocated by swsusp, so using the nosave regions directly won't save us >>>much. >> >>Well I think it is a cleaner though. > > > This is a matter of opinion, too ... Well, as I'm not volunteering to maintain swsusp, if your opinion is that your way is cleaner, I can't argue ;) So long as it stops wasting those page flags then I'm happy. However the register_nosave API really should use locking, I think. There is absolutely no downside, AFAIKS. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxx https://lists.osdl.org/mailman/listinfo/linux-pm
