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[27.32.36.31]) by smtp.gmail.com with ESMTPSA id h5sm16037129pfn.12.2020.11.15.17.49.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Nov 2020 17:49:05 -0800 (PST) Date: Mon, 16 Nov 2020 11:48:58 +1000 From: Nicholas Piggin Subject: Re: [PATCH 1/3] asm-generic/atomic64: Add support for ARCH_ATOMIC To: Christophe Leroy , Peter Zijlstra Cc: Alexey Kardashevskiy , Arnd Bergmann , Boqun Feng , Christophe Leroy , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Michael Ellerman , Will Deacon References: <20201111110723.3148665-1-npiggin@gmail.com> <20201111110723.3148665-2-npiggin@gmail.com> <3086114c-8af6-3863-0cbf-5d3956fcda95@csgroup.eu> <20201111134412.GT2611@hirez.programming.kicks-ass.net> In-Reply-To: <20201111134412.GT2611@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Message-Id: <1605491118.ek4lw8ppgq.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Excerpts from Peter Zijlstra's message of November 11, 2020 11:44 pm: > On Wed, Nov 11, 2020 at 02:39:01PM +0100, Christophe Leroy wrote: >> Hello, >>=20 >> Le 11/11/2020 =C3=A0 12:07, Nicholas Piggin a =C3=A9crit=C2=A0: >> > This passes atomic64 selftest on ppc32 on qemu (uniprocessor only) >> > both before and after powerpc is converted to use ARCH_ATOMIC. >>=20 >> Can you explain what this change does and why it is needed ? >=20 > That certainly should've been in the Changelog. This enables atomic > instrumentation, see asm-generic/atomic-instrumented.h. IOW, it makes > atomic ops visible to K*SAN. >=20 Right. This specific patch doesn't actually "do" anything except allow generic atomic64 to be used with ARCH_ATOMIC. It does that by re-naming some things to avoid name collisions and also providing the arch_ prefix that ARCH_ATOMIC expects. I don't know what should be in the changelog. I suppose the latter, the former is discoverable by looking at ARCH_ATOMIC code and patches but I guess it's polite and doesn't hurt to include the former as well. I'll send an update before long. Thanks, Nick