On Mon, Jan 04, 2016 at 02:36:58PM +0100, Peter Zijlstra wrote: > On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote: > > On Sat, Jan 02, 2016 at 11:24:38AM +0000, Russell King - ARM Linux wrote: > > > > My only concern is that it gives people an additional handle onto a > > > "new" set of barriers - just because they're prefixed with __* > > > unfortunately doesn't stop anyone from using it (been there with > > > other arch stuff before.) > > > > > > I wonder whether we should consider making the smp memory barriers > > > inline functions, so these __smp_xxx() variants can be undef'd > > > afterwards, thereby preventing drivers getting their hands on these > > > new macros? > > > > That'd be tricky to do cleanly since asm-generic depends on > > ifndef to add generic variants where needed. > > > > But it would be possible to add a checkpatch test for this. > > Wasn't the whole purpose of these things for 'drivers' (namely > virtio/xen hypervisor interaction) to use these? My take out from discussion with you was that virtualization is probably the only valid use-case. So at David Miller's suggestion there's a patch later in the series that adds virt_xxxx wrappers and these are then used by virtio xen and later maybe others. > And I suppose most of virtio would actually be modules, so you cannot do > what I did with preempt_enable_no_resched() either. > > But yes, it would be good to limit the use of these things. Right so the trick is checkpatch warns about use of __smp_xxx and hopefully people are not crazy enough to use virt_xxx variants for non-virtual drivers. -- MST
