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[106.167.171.201]) by smtp.gmail.com with ESMTPSA id c24-20020a170902d91800b001c9ab91d3d7sm1657340plz.37.2023.10.20.08.24.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Oct 2023 08:24:55 -0700 (PDT) Message-ID: <03ea8aea-2d0c-48ab-bb0d-e585571f1926@gmail.com> Date: Sat, 21 Oct 2023 00:24:50 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH memory-model] docs: memory-barriers: Add note on compiler transformation and address deps To: paulmck@kernel.org, Jonas Oberhauser Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, Alan Stern , Andrea Parri , Will Deacon , Peter Zijlstra , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Daniel Lustig , Joel Fernandes , Jonathan Corbet References: <4110a58a-8db5-57c4-2f5a-e09ee054baaa@huaweicloud.com> <1c731fdc-9383-21f2-b2d0-2c879b382687@huaweicloud.com> <2694e6e1-3282-4a69-b955-06afd7d7f87f@paulmck-laptop> Content-Language: en-US From: Akira Yokosawa In-Reply-To: <2694e6e1-3282-4a69-b955-06afd7d7f87f@paulmck-laptop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Hi Paul, On 2023/10/20 22:57, Paul E. McKenney wrote: > On Fri, Oct 20, 2023 at 11:29:24AM +0200, Jonas Oberhauser wrote: >> >> Am 10/19/2023 um 6:39 PM schrieb Paul E. McKenney: >>> On Wed, Oct 18, 2023 at 12:11:58PM +0200, Jonas Oberhauser wrote: [...] >>>> Am 10/6/2023 um 6:39 PM schrieb Jonas Oberhauser: >>>>> Hi Paul, >>>>> >>>>> The "more up-to-date information" makes it sound like (some of) the >>>>> information in this section is out-of-date/no longer valid. >>> The old smp_read_barrier_depends() that these section cover really >>> does no longer exist. >> >> You mean that they *intend to* cover? smp_read_barrier_depends never appears >> in the text, so anyone reading this section without prior knowledge has no >> way of realizing that this is what the sections are talking about. > > It also doesn't appear in the kernel anymore. > >> On the other hand the implicit address dependency barriers that do exist are >> mentioned in the text. And that part is still true. > > And this relevant discussion is moving to rcu_dereference.rst, and the > current text is just for people who read memory-barriers.txt some time > back and are expecting to find the same information in the same place. > > So if there are things that rcu_dereference.rst is missing, they do > need to be added. As far as I can see, there is no mention of "address dependency" in rcu_dereference.rst. Yes, I see the discussion in rcu_dereference.rst is all about how not to break address dependency by proper uses of rcu_dereference() and its friends. But that might not be obvious for readers who followed the references placed in memory-barriers.txt. Using the term "address dependency" somewhere in rcu_dereference.rst should help such readers, I guess. [...] >> >> Thanks for the response, I started thinking my mails aren't getting through >> again. Jonas, FWIW, your email archived at https://lore.kernel.org/linux-doc/1c731fdc-9383-21f2-b2d0-2c879b382687@huaweicloud.com/ didn't reach my gmail inbox. I looked for it in the spam folder, but couldn't find it there either. Your first reply on Oct 6, which is archived at https://lore.kernel.org/linux-doc/4110a58a-8db5-57c4-2f5a-e09ee054baaa@huaweicloud.com/ ended up in my spam folder. I have no idea why gmail has trouble with your emails so often ... Anyway, LKML did accept your mails this time. HTH, Akira