From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Waiman Long <waiman.long@hpe.com>, Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [PATCH] locking/qrwlock: Allow multiple spinning readers
Date: Fri, 1 Apr 2016 21:53:29 +0200 [thread overview]
Message-ID: <20160401195329.GO3448@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160401164742.GD3991@arm.com>
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 ;-)
prev parent reply other threads:[~2016-04-01 19:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-20 3:21 [PATCH] locking/qrwlock: Allow multiple spinning readers Waiman Long
2016-03-20 10:43 ` Peter Zijlstra
2016-03-22 2:21 ` Waiman Long
2016-03-29 20:20 ` Peter Zijlstra
2016-03-31 22:12 ` Waiman Long
2016-04-01 10:29 ` Peter Zijlstra
2016-04-01 10:31 ` Peter Zijlstra
2016-04-01 10:41 ` Will Deacon
2016-04-01 10:54 ` Peter Zijlstra
2016-04-01 11:43 ` Peter Zijlstra
2016-04-01 16:47 ` Will Deacon
2016-04-01 19:53 ` Peter Zijlstra [this message]
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