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Date: Fri, 24 Mar 2017 21:46:15 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: locking/atomic: Introduce atomic_try_cmpxchg()
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On Fri, Mar 24, 2017 at 12:08:32PM -0700, Linus Torvalds wrote:
> On Fri, Mar 24, 2017 at 10:23 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > I tried a few variants, but nothing really made it better.
> 
> So I really hate how your thing has two return values, and fakes the
> second one using the pointer value. 

Inspired by C11 I'm afraid..

> So how about we change the interface entirely, with the goal being
> both type safety and good code generation?

I certainly like it better, but so far I'm having trouble reproducing
your results. What compiler version are you on?