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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429897ff3f5sm5951290f8f.22.2025.10.23.14.14.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Oct 2025 14:14:53 -0700 (PDT) Date: Thu, 23 Oct 2025 22:14:50 +0100 From: David Laight To: Linus Torvalds Cc: Thomas Gleixner , LKML , Peter Zijlstra , Darren Hart , Davidlohr Bueso , =?UTF-8?B?QW5kcsOp?= Almeida , kernel test robot , Russell King , linux-arm-kernel@lists.infradead.org, x86@kernel.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , linuxppc-dev@lists.ozlabs.org, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Heiko Carstens , Christian Borntraeger , Sven Schnelle , linux-s390@vger.kernel.org, Mathieu Desnoyers , Andrew Cooper , Julia Lawall , Nicolas Palix , Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org Subject: Re: [patch V4 10/12] futex: Convert to scoped user access Message-ID: <20251023221450.1303003d@pumpkin> In-Reply-To: References: <20251022102427.400699796@linutronix.de> <20251022103112.478876605@linutronix.de> <873479xxtu.ffs@tglx> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 23 Oct 2025 09:26:12 -1000 Linus Torvalds wrote: > On Thu, 23 Oct 2025 at 08:44, Thomas Gleixner wrote: > > > > But as you said out-of-line function call it occured to me that these > > helpers might be just named get/put_user_inline(). Hmm? > > Yeah, with a comment that clearly says "you need to have actual > performance numbers for why this needs to be inlined" for people to > use it. Avoiding an extra clac/stac pair for two accesses might be enough. But for a single access it might be hard to justify. (Even if 'return' instructions are horribly painful. Although anyone chasing performance is probably using a local system and just disables all that 'stuff'.) > > Linus