Messages in this thread | | | Date | Thu, 16 Jan 2014 11:36:59 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock() |
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On Thu, Jan 16, 2014 at 06:39:23AM +0700, Linus Torvalds wrote: > On Jan 16, 2014 6:22 AM, "Peter Zijlstra" <peterz@infradead.org> wrote: > > > > So while the primitive is called smp_store_release() the !SMP variant > > still does: > > > > *(volatile __type *) = ptr; > > > > which should not compile on any Alpha pre EV56, SMP or no for __type == > > u8. > > I'm not sure where you get that "should not compile" theory from. > > I'm pretty sure it will compile just fine. It will just generate the same > standard read-modify-write sequence (and not using the ldl/stc sequence > either). Do you have any actual reason to believe it won't, apart from your > theoretical wishes of how the world should work?
No, I earlier even said it probably would compile. My usage of 'should' comes from how we've 'defined' volatile/ACCESS_ONCE in Documentation/memory-barriers.txt. According to those constraints the rmw cycle is not proper code.
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