On Wed, Jan 06, 2016 at 09:51:52AM +0800, Boqun Feng wrote: > On Tue, Jan 05, 2016 at 06:16:48PM +0200, Michael S. Tsirkin wrote: > [snip] > > > > > Another thing is that smp_lwsync() may have a third user(other than > > > > > smp_load_acquire() and smp_store_release()): > > > > > > > > > > http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 > > > > > > > > > > I'm OK to change my patch accordingly, but do we really want > > > > > smp_lwsync() get involved in this cleanup? If I understand you > > > > > correctly, this cleanup focuses on external API like smp_{r,w,}mb(), > > > > > while smp_lwsync() is internal to PPC. > > > > > > > > > > Regards, > > > > > Boqun > > > > > > > > I think you missed the leading ___ :) > > > > > > > > > > What I mean here was smp_lwsync() was originally internal to PPC, but > > > never mind ;-) > > > > > > > smp_store_release is external and it needs __smp_lwsync as > > > > defined here. > > > > > > > > I can duplicate some code and have smp_lwsync *not* call __smp_lwsync > > > > > > You mean bringing smp_lwsync() back? because I haven't seen you defining > > > in asm-generic/barriers.h in previous patches and you just delete it in > > > this patch. > > > > > > > but why do this? Still, if you prefer it this way, > > > > please let me know. > > > > > > > > > > I think deleting smp_lwsync() is fine, though I need to change atomic > > > variants patches on PPC because of it ;-/ > > > > > > Regards, > > > Boqun > > > > Sorry, I don't understand - why do you have to do anything? > > I changed all users of smp_lwsync so they > > use __smp_lwsync on SMP and barrier() on !SMP. > > > > This is exactly the current behaviour, I also tested that > > generated code does not change at all. > > > > Is there a patch in your tree that conflicts with this? > > > > Because in a patchset which implements atomic relaxed/acquire/release > variants on PPC I use smp_lwsync(), this makes it have another user, > please see this mail: > > http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 > > in definition of PPC's __atomic_op_release(). > > > But I think removing smp_lwsync() is a good idea and actually I think we > can go further to remove __smp_lwsync() and let __smp_load_acquire and > __smp_store_release call __lwsync() directly, but that is another thing. > > Anyway, I will modify my patch. > > Regards, > Boqun Thanks! Could you send an ack then please? > > > > > > > > WRITE_ONCE(*p, v); \ > > > > > > } while (0) > > > > > > > > > > > > -#define smp_load_acquire(p) \ > > > > > > +#define __smp_load_acquire(p) \ > > > > > > ({ \ > > > > > > typeof(*p) ___p1 = READ_ONCE(*p); \ > > > > > > compiletime_assert_atomic_type(*p); \ > > > > > > - smp_lwsync(); \ > > > > > > + __smp_lwsync(); \ > > > > > > ___p1; \ > > > > > > }) > > > > > > > > > > > > -- > > > > > > MST > > > > > > > > > > > > -- > > > > > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > > > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > Please read the FAQ at http://www.tux.org/lkml/
