linux-kernel - Re: [RFC PATCH] locking/atomics/powerpc: Introduce optimized cmpxchg

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Date:   Sun, 06 May 2018 11:56:44 +1000
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        aryabinin@...tuozzo.com, boqun.feng@...il.com,
        catalin.marinas@....com, dvyukov@...gle.com, will.deacon@....com
Subject: Re: [RFC PATCH] locking/atomics/powerpc: Introduce optimized
 cmpxchg_release() family of APIs for PowerPC

On Sat, 2018-05-05 at 12:00 +0200, Ingo Molnar wrote:
> This clearly suggests that PPC_RELEASE_BARRIER is in active use and 'lwsync' is 
> the 'release barrier' instruction, if I interpreted that right.

The closest to one we got.

The semantics are that it orders all load/store pairs to cachable
storage except store+load.

Cheers,
Ben.