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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 25 Mar 2017 11:28:35 -0700
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Subject: Re: locking/atomic: Introduce atomic_try_cmpxchg()
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        "H. Peter Anvin" <hpa@zytor.com>, Josh Poimboeuf <jpoimboe@redhat.com>,
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On Sat, Mar 25, 2017 at 11:20 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> Added above, a few bytes smaller than the shiny new one actually.

Hmm. Sad. The label approach looked like it would match the semantics
of cmpxchg perfectly, but it's not as optimal as it superficially
would have seemed.

And I assume that register allocation etc is different enough that
there's no sane way to diff the asm to see what changed.

           Linus