[{"id":3683310,"web_url":"http://patchwork.ozlabs.org/comment/3683310/","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","sparclinux@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; 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Tue, 28 Apr 2026\n 02:25:24 -0700 (PDT)"],"Precedence":"bulk","X-Mailing-List":"sparclinux@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","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; 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