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Mon, 15 May 2023 05:43:39 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-415-gf2b17fe6c3-fm-20230503.001-gf2b17fe6 Mime-Version: 1.0 Message-Id: <4975b92f-92f6-4d50-8386-9add12ddfd61@app.fastmail.com> In-Reply-To: <20230515075659.118447996@infradead.org> References: <20230515075659.118447996@infradead.org> Date: Mon, 15 May 2023 11:42:23 +0200 From: "Arnd Bergmann" To: "Peter Zijlstra" , "Linus Torvalds" Cc: "Jonathan Corbet" , "Will Deacon" , "Boqun Feng" , "Mark Rutland" , "Catalin Marinas" , dennis@kernel.org, "Tejun Heo" , "Christoph Lameter" , "Heiko Carstens" , gor@linux.ibm.com, "Alexander Gordeev" , borntraeger@linux.ibm.com, "Sven Schnelle" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Dave Hansen" , x86@kernel.org, "H. Peter Anvin" , "Joerg Roedel" , suravee.suthikulpanit@amd.com, "Robin Murphy" , "David Woodhouse" , "Baolu Lu" , "Herbert Xu" , "David S . Miller" , "Pekka Enberg" , "David Rientjes" , "Joonsoo Kim" , "Andrew Morton" , "Vlastimil Babka" , "Roman Gushchin" , "Hyeonggon Yoo" <42.hyeyoo@gmail.com>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, iommu@lists.linux.dev, Linux-Arch , linux-crypto@vger.kernel.org Subject: Re: [PATCH v3 00/11] Introduce cmpxchg128() -- aka. the demise of cmpxchg_double() Content-Type: text/plain X-Stat-Signature: ewtytw53a4z9qh18trrphsmoi9kryza8 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C602040006 X-Rspam-User: X-HE-Tag: 1684143822-681958 X-HE-Meta: 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 5BfPlou7 5fQwX0SAcZpmNtq2idHqbh1AborvLmpxuM+EFOPG6cLtb3Ri2kc5nwYM271E8RN1bZM8W6myCRTt9JHEuvyp8SiYuaGjYZvQSyJs08CGDIENrc3ynQ5IVkf+MkMCS6PTN9WTWkMSf9e77IoOLM5EqLscjVBSvgoxpu+CsPGeiVdw08Ztal3PXvx1B6upVZC3JgUZHuXvnR6WHlSIjFRMji12mh2g6yJ4vlPcFMpESay/70F0innCom4kxc6MCjtxUYFQ7w1UM7zauHV4iC5AocdtL8w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 15, 2023, at 09:56, Peter Zijlstra wrote: > > Since v2: > > - reworked this_cpu_cmpxchg() to not implicity do u128 but provide explicit > this_cpu_cmpxchg128() (arnd) > - added try_cmpxchg12_local() (per the addition of the try_cmpxchg*_local() > family of functions) > - slight cleanup of the SLUB conversion (due to rebase and having to touch it) > - added a 'cleanup' patch for SLUB, since I was staring at that anyway > This is clearly an improvement over the previous state, so I'm happy with that, and the explicit this_cpu_cmpxchg128() interface addresses most of my previous concerns. Reviewed-by: Arnd Bergmann The need for runtime feature checking in the callers on x86-64 is still a bit awkward, but this is no worse than before. I understand that turning this into a compile-time choice would require first settling a larger debate about raising the default target for distros beyond the current CONFIG_GENERIC_CPU. Arnd