From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9919FCCD1BF for ; Thu, 23 Oct 2025 21:15:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=z6sEiHIDuaPc1r9BapkeRLwxlBj8uKP+Q15MeH29iBY=; b=n7eqbwfLe3U3jrNrhbP/EUtfRN IW74z9hRDyCt5kB9tPcgEu1e9McdePLwLTQ5cxbms51WT1DhKJXP2WKcJt2ayrkQ57rO9eNP1218r T7oY9M8ERGNvCZxKapEBqRpDoHjhdmtsNPkcIVPJR8w9HyT+MS1A1R4g/w3MIir3psLA9ar1s6rWb DTjYu5N/27cN/SVO7rLY+VOIpRqHbciiBAQsmwsZPaVo97tWpGKY+2Ars4ztUX7MQkOnSIz3G29WE l93/oRLjc7mUVL8J2zn8G6dykYKx44RMCZf5U2c3hRrymjo3Iq1uAzSU2Ou/A6HvbwnzxOyGsAPIe DH2bDWnw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vC2eC-00000007cfV-0Hof; Thu, 23 Oct 2025 21:15:00 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vC2eA-00000007cfG-3fEy for linux-arm-kernel@bombadil.infradead.org; Thu, 23 Oct 2025 21:14:59 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=z6sEiHIDuaPc1r9BapkeRLwxlBj8uKP+Q15MeH29iBY=; b=lnOU+B7TlZ2WrLmZYn7ahzJvx2 iimPjo6MrAV/0EX/+LhsDsoQvrz0ANXJO/03uBtWUn0U7kbaDFUdBlTkh1Wh307eH+ELEpB/nRPtP HSwlTPTLiBgOtrUWVbUAn4ALNqEH61JfNShCK2EVE2jPKpQF8mNhbAmLeRNwlfiRy68imN3a3Tw5q ipRmbiOKnAqrFTKtZg+s7xfJ3kXBGOT8RQZ2Z7DpEJ2TwBN2uLM1oelhZbQ6iCTnr9CV1dgPE6gEp qQ5i32j/sJHTy454Zlni5sw0jq30rIDmspcz76lSWGEM0XSPNYzpZc65XsU89WCp7FU4cbDhHn7dP /YBVYYBw==; Received: from mail-wr1-x432.google.com ([2a00:1450:4864:20::432]) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vC1mT-00000001lT4-0Scf for linux-arm-kernel@lists.infradead.org; Thu, 23 Oct 2025 20:19:30 +0000 Received: by mail-wr1-x432.google.com with SMTP id ffacd0b85a97d-3ecde0be34eso1644010f8f.1 for ; Thu, 23 Oct 2025 14:14:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1761254093; x=1761858893; darn=lists.infradead.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=z6sEiHIDuaPc1r9BapkeRLwxlBj8uKP+Q15MeH29iBY=; b=AOiSM1X3ScYZBNIeIckcc/m0pZJsuSlGDyEMWzRijc5O11NQzzkfnJjJ9JTR0oRios 6wsP+ZxuWMz0l/fXY8e+9GmxB9Z8JpthjUMwfC6fLoDA+6sMz2isCwgL8SFImSy45dBJ 6HLFTBkB0JTGAh8ZKCReDcIH+vyiT6Ok0DLjZOsHxlyboCH5lHH5gj6+9NOtSJLqBN0U 5mlCRWZrFSm2vkFeO070J9adbb/U1PV8mpCK8+YytzqfUdhjeOTq8vf8LAE+kD560OQa fPyTR3fuDQe0VX6AqAwoLJSkk9PFszz35ksQpQjNPAJasELMifJmOO9ySFX5rf3rzKEH 5Vaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761254093; x=1761858893; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=z6sEiHIDuaPc1r9BapkeRLwxlBj8uKP+Q15MeH29iBY=; b=bkoQdpiJg7smA68QoUMs8oYvYP4hOvjkM7eRTySlv7xA1QgCZEuLi5Qp+JEDHIdTMj X0ERavyeihBUahudxlzRQW13WOeyIaaoemJOrcVe3/CBIuN9oEPX8nFumR8pD14tNEmO JwX/EJ6gf1//xvASP/7h1i/JZRBRFpuwtYYEOq4YV+wfsJpn0dvniRHJHECOUS/wrk/9 drIdyUjjxkAqbRQItMTd580CxIEhHIVq6IWUmQIe6F+Ho29h2yfpWYAWJfhoycFudcu/ 52qqQUkN/RyiEUTeBQ2+XqM3xvqz9mG7O6+XAOsrtafsmbaBA+Rdu3Zw+uyy+9bJw6MF yl+Q== X-Forwarded-Encrypted: i=1; AJvYcCXa6vrnCT1RjqExMqmqo0t7KWLy6rSbJzul52/ZAOgbp64asvnMMooZAy80Oo8QNcrDJSTOX7wFUIecsI8AF4W3@lists.infradead.org X-Gm-Message-State: AOJu0YyWVWljG+m+axGGVaM7VTIIkPOMrTW24QVLMhwxT2QHvpXev6Fb GtIP3TlIp1sYHJWzR0litW6BqU75lb7xgqiBDsn1RW1bFXbm14+I18jN X-Gm-Gg: ASbGncvpp7q5JcskDrUe4kglMnFBO5V6I18wh0zssk/1ShIVLfR9XMcfaMR77ch2f7V JWOpH7ecRVUCpP9l89tGAvCC5EMY+QpRaYkn7ZoRAHgcp06Pbt3dbZAc2WXpKLPUbk72ae+pBfL zxoSrvWRPuMiEUvgI6YYf/GMfqc8w2oMWia4F9lfqBVfl+RUk88uvU++OrcPv+AmY6Ml3x8YO7G IjiRe+MwYebfA43bIWqDakTPqv9UwS6RpEOZhhr1NQIcBgsLBT1XYSYJ/wxxLYlnwUWXgKGCvDy rGPXKObeo/9YbfV1ZmBlmLYCp9OmAJ1Au61F4Fo5guXs4WlQfFc8zb5AJ6WEJak4Nk8XpYbQCj/ RV0FHsTwN+FZdIxAOHiRUd7CzJwla2XlOhcwYK7XPJhwVyI4k6Hz1Zklh64MlhbgRGK2mIti37Y QKsiy7plKQrO0oGyzwSUflKsGyxvG8PiTdi5ndcMb3KQ== X-Google-Smtp-Source: AGHT+IGk8eEDWy3Lb1qhGeYZ8N0urG/YCIu8xY7+WZCUmyVKdYxjr9Zc6A6l5BFcgm2g7Vw9SfAVXA== X-Received: by 2002:a05:6000:1446:b0:427:374:d91e with SMTP id ffacd0b85a97d-4298f545550mr248975f8f.11.1761254093423; Thu, 23 Oct 2025 14:14:53 -0700 (PDT) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [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) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251023_211929_228118_B9ED6085 X-CRM114-Status: GOOD ( 15.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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