Messages in this thread | | | Date | Fri, 1 Apr 2016 21:53:29 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] locking/qrwlock: Allow multiple spinning readers |
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On Fri, Apr 01, 2016 at 05:47:43PM +0100, Will Deacon wrote: > > +#define smp_cond_load_acquire(ptr, cond_expr) ({ \ > > + typeof(ptr) __PTR = (ptr); \ > > + typeof(*ptr) VAL; \ > > It's a bit grim having a magic variable name, but I have no better > suggestion.
Right; we had this discussion and this is the best we could come up with.
lkml.kernel.org/r/CA+55aFzZA9EB3hFptSpdmeMOifeM5BWQGOW+ib7SLvyMTETzaA@mail.gmail.com
> > + for (;;) { \ > > + VAL = READ_ONCE(*__PTR); \ > > + if (cond_expr) \ > > + break; \ > > + cpu_relax(); \ > > + } \ > > + smp_rmb(); /* ctrl + rmb := acquire */ \ > > + VAL; \ > > +}) > > Can you stick some #ifndef guards around this, please?
Oh sure; I'll even compile and boot it when I find a moment ;-)
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