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Date:   Fri, 4 Jun 2021 21:17:56 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Segher Boessenkool <segher@kernel.crashing.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Will Deacon <will@kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
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        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Subject: Re: [RFC] LKMM: Add volatile_if()
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On Fri, Jun 04, 2021 at 12:24:07PM -0500, Segher Boessenkool wrote:
> On Fri, Jun 04, 2021 at 10:10:29AM -0700, Linus Torvalds wrote:
> > The compiler *cannot* just say "oh, I'll do that 'volatile asm
> > barrier' whether the condition is true or not". That would be a
> > fundamental compiler bug.
> 
> Yes.

So we can all agree on something like this?

#define volatile_if(x) \
	if (({ _Bool __x = (x); BUILD_BUG_ON(__builtin_constant_p(__x)); __x; }) && \
	    ({ barrier(); 1; }))

Do we keep volatile_if() or do we like ctrl_dep_if() better?