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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> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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