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[142.167.56.70]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7dcdc0f5d42sm515494885a.28.2025.07.14.07.34.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Jul 2025 07:34:44 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1ubKGR-00000008ft9-1MVt; Mon, 14 Jul 2025 11:34:43 -0300 Date: Mon, 14 Jul 2025 11:34:43 -0300 From: Jason Gunthorpe To: Mike Rapoport Cc: Pratyush Yadav , Christian Brauner , Pasha Tatashin , jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, zhangguopeng@kylinos.cn, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, gregkh@linuxfoundation.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com Subject: Re: [RFC v2 10/16] luo: luo_ioctl: add ioctl interface Message-ID: <20250714143443.GF1870174@ziepe.ca> References: <20250515182322.117840-1-pasha.tatashin@soleen.com> <20250515182322.117840-11-pasha.tatashin@soleen.com> <20250624-akzeptabel-angreifbar-9095f4717ca4@brauner> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 494F912000C X-Stat-Signature: dkrzbp7jus7jencwdihbntw4g5sieh3c X-Rspam-User: X-HE-Tag: 1752503687-354371 X-HE-Meta: U2FsdGVkX1//cGcVpDJaKBDkjWoSiV7riQFEjYoh5/SLLW2KeefvgYIUcn1e9z99DAAhR4r8svtX46+ip7FgwrtsyAcnpipQtFbKlipqHpmzgWum9TB8IO6AEZ1ev2jE0pXcwwObde0VA677FQ+AWAhKw0rkkFRMhGeCbacmCKtZhMT7/30T6x45qVKDlYpBWK6R17u0KuoQ4WpT9SQawKvmWvOCmTH5GrJza3PvbXhHmeXgli3BQoeX6DzjvS9AI0gZPgT15VWmWexrhM+Y0dFKUHRY5LRnLmgVysioUXuMVsZ0rXBFXRgKBJWcd7SCT5PpRtgzZVm91qvrvkWBL2mH1xVVK2dPp8ftC+RjLF78xP5zMf1QJsHc3Y4OhlfipRy28GrfnunDPC366V+sopIf9BW9+3lghubWWfOXUYM3fRknsbUuGepon2IUPa2XMt94/z/XIX46Smg+m3EZXJ/7QDP6Y43g3dYRfQ9gKZ2ez3ihfdMaOMb7SeLnnNqhIcQD38HrDkYgI11zN1LqjtIHx42eU9g6F4vq5eq4O5HvwQGFqjwrot2FhtH7bnJbdCaHaTUuzVRfjE042V88MxmeeIx/QzxQcXL8mRt4TAYm0LG1NEEQVnxNanJKWDbuwlkfbVI8iGGWseObwdlAAdOM/mvF1RnEB7vE8OBSEI6bf/wa1E/zWn7EZ4Ox0QRUQa/bmeJ39KhM+Kij45p4ny2BcoTlBbwamkUyQOKfI3guWxt/ZYIHf80sjqpuW62lq/ge03DqBycry+QMJqOGsQHQZ7CRzP0d4em7iMcA2K1v1MMUOmlR93gvuRftbW982gWU8jx0U+Cs+x3Ea5rowXVMt/vRkCJd9UYeUJyG3OrCAVzqsKHCeJKXFaC7LA5QUpgXjuxZn5pA/bcBeCpiFL9+hgKB6S5YTq+VPTQRPP2KXqYmV1XYUIO1zVP5iiHe18FJwIRj8t1WODKZ5sm iGe3opj2 /IaIh5JxSXhQM60RiNF783zoK4xz3k1EGltL7lc+dAKwduMPjQWqQ9c02Jf5vDNdXANKJKsGUW7HpMWFn5GhT/+vRoLhjlW5lQLfXCw0Z2umeAcs3P/jectheOeyTgs0e0QLNZ2puElhAnTw3TJeaaZYhFZgVvTS0DqkthibY/S1b5HYj2vTepd9IeFVo1a/e9VxHac0gSZoYv1tizV+aYaxJzXZUtZvMBs6KDjhHEgu+gZ8/Hr61LEdJqO9jWWsFLnRpPsCnBL9IlKhqkObhLDaIk0P6KfA3EDBkBHFhoszd2JWOWdLRsAzB6AKHN5R5w0mK5ImLzou8oSwvEEL6dyaQPPilnnFxuUZQZvS0H+IU4lzWNaA2+/KpBLgXPScSgbvXPZb1coNvA2W8lPLP9JZMCw== 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: List-Subscribe: List-Unsubscribe: On Thu, Jul 10, 2025 at 10:26:45AM +0300, Mike Rapoport wrote: > IIUC Christian's point was mostly not about using VFS APIs (i.e. > read/write) but about using a special pseudo fs rather than devtmpfs to > drive ioctls. > > So instead of > > fd = open("/dev/liveupdate", ...); > ioctl(fd, ...); > > we'd use > > fd = open("/sys/fs/kexec/control", ...); > ioctl(fd, ...); Please no, /sys/ is much worse. /dev/ has lots of infrastructure to control permissions/etc that /sys/ does not. If you want to do ioctls to something that you open() is a character dev and you accept the limitations with namespaces, coarse permissions and so on. Jason