[{"id":3683298,"web_url":"http://patchwork.ozlabs.org/comment/3683298/","msgid":"","list_archive_url":null,"date":"2026-04-28T09:25:11","subject":"Re: [RFC PATCH v1 4/9] uaccess: Introduce\n copy_{to/from}_user_partial()","submitter":{"id":703,"url":"http://patchwork.ozlabs.org/api/people/703/","name":"Geert Uytterhoeven","email":"geert@linux-m68k.org"},"content":"Hi Christophe,\n\nThanks for your patch!\n\nOn Mon, 27 Apr 2026 at 19:18, Christophe Leroy (CS GROUP)\n wrote:\n> Today there are approximately 3000 calls for copy_to_user() and\n> 3000 calls to copy_from_user().\n>\n> The majority of callers of copy_{to/from}_user() don't care about the\n> return value, they only check whether it is 0 or not, and when it is\n> not 0 they handle it as a -EACCES.\n\nI think the \"a\" can be dropped.\n\n> In order to allow better optimisation of copy_{to/from}_user() when\n> the size of the copy is known at build time, create new fonctions\n\nfunctions\n\n> named copy_{to/from}_user_partial() to be used by the few callers\n> that are interested in partial copies and need to now how many\n\nknow\n\n> bytes remain at the end of the copy.\n>\n> For the time being it is just the same as copy_{to/from}_user().\n>\n> Signed-off-by: Christophe Leroy (CS GROUP) \n\nGr{oetje,eeting}s,\n\n Geert","headers":{"Return-Path":"\n ","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n secure) header.d=lists.infradead.org header.i=@lists.infradead.org\n header.a=rsa-sha256 header.s=bombadil.20210309 header.b=NdXUQ795;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=none (no SPF record) smtp.mailfrom=lists.infradead.org\n (client-ip=2607:7c80:54:3::133; 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Tue, 28 Apr 2026\n 02:25:24 -0700 (PDT)"],"MIME-Version":"1.0","References":"\n ","In-Reply-To":"\n ","From":"Geert Uytterhoeven ","Date":"Tue, 28 Apr 2026 11:25:11 +0200","X-Gmail-Original-Message-ID":"\n ","X-Gm-Features":"AVHnY4JEWBVPw4tSjHgbQTia8gZd2WGJ1sv6qLdKJbtvs4hms1blpvc35yb0VWw","Message-ID":"\n ","Subject":"Re: [RFC PATCH v1 4/9] uaccess: Introduce\n copy_{to/from}_user_partial()","To":"\"Christophe Leroy (CS GROUP)\" ","Cc":"Yury Norov , Andrew Morton ,\n\tLinus Torvalds ,\n David Laight ,\n\tThomas Gleixner , linux-alpha@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org,\n\tlinux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,\n\tlinuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,\n\tlinux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,\n\tsparclinux@vger.kernel.org, linux-um@lists.infradead.org,\n\tdmaengine@vger.kernel.org, linux-efi@vger.kernel.org,\n\tlinux-fsi@lists.ozlabs.org, amd-gfx@lists.freedesktop.org,\n\tdri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,\n\tlinux-wpan@vger.kernel.org, netdev@vger.kernel.org,\n\tlinux-wireless@vger.kernel.org, linux-spi@vger.kernel.org,\n\tlinux-media@vger.kernel.org, linux-staging@lists.linux.dev,\n\tlinux-serial@vger.kernel.org, linux-usb@vger.kernel.org,\n\txen-devel@lists.xenproject.org, linux-fsdevel@vger.kernel.org,\n\tocfs2-devel@lists.linux.dev, bpf@vger.kernel.org, kasan-dev@googlegroups.com,\n\tlinux-mm@kvack.org, linux-x25@vger.kernel.org,\n rust-for-linux@vger.kernel.org,\n\tlinux-sound@vger.kernel.org, sound-open-firmware@alsa-project.org,\n\tlinux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org,\n\tloongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org,\n\tlinux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org,\n\tlinux-sh@vger.kernel.org, linux-arch@vger.kernel.org","Content-Type":"text/plain; charset=\"UTF-8\"","X-CRM114-Version":"20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 ","X-CRM114-CacheID":"sfid-20260428_023122_140667_1283E209 ","X-CRM114-Status":"GOOD ( 24.41 )","X-Spam-Score":"-1.6 (-)","X-Spam-Report":"Spam detection software,\n running on the system \"bombadil.infradead.org\",\n has NOT identified this incoming email as spam. The original\n message has been attached to this so you can view it or label\n similar future email. If you have any questions, see\n the administrator of that system for details.\n Content preview: Hi Christophe, Thanks for your patch! On Mon, 27 Apr 2026\n at 19:18, Christophe Leroy (CS GROUP) wrote: > Today\n there are approximately 3000 calls for copy_to_user() and > 3000 calls to\n copy_from_user(). > > The majori [...]\n Content analysis details: (-1.6 points, 5.0 required)\n pts rule name description\n ---- ----------------------\n --------------------------------------------------\n -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no\n trust\n [209.85.208.49 listed in list.dnswl.org]\n 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record\n -0.0 SPF_PASS SPF: sender matches SPF record\n -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1%\n [score: 0.0000]\n 0.2 HEADER_FROM_DIFFERENT_DOMAINS From and EnvelopeFrom 2nd level mail\n domains are different\n 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail\n provider\n [geert.uytterhoeven(at)gmail.com]\n 0.0 FREEMAIL_FORGED_FROMDOMAIN 2nd level domains in From and EnvelopeFrom\n freemail headers are different\n 0.0 RCVD_IN_MSPIKE_H2 RBL: Average reputation (+2)\n [209.85.208.49 listed in wl.mailspike.net]","X-BeenThere":"linux-um@lists.infradead.org","X-Mailman-Version":"2.1.34","Precedence":"list","List-Id":"","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Sender":"\"linux-um\" ","Errors-To":"linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org"}}]