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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47B64C83F1B for ; Wed, 16 Jul 2025 09:43:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DE1178D0006; Wed, 16 Jul 2025 05:43:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DB9068D0001; Wed, 16 Jul 2025 05:43:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CF5BF8D0006; Wed, 16 Jul 2025 05:43:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id BC2B38D0001 for ; Wed, 16 Jul 2025 05:43:36 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 5E93AC0315 for ; Wed, 16 Jul 2025 09:43:36 +0000 (UTC) X-FDA: 83669640432.16.2BEEAF2 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf05.hostedemail.com (Postfix) with ESMTP id A126E100009 for ; Wed, 16 Jul 2025 09:43:34 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linuxfoundation.org header.s=korg header.b=QccxkNiH; dmarc=pass (policy=none) header.from=linuxfoundation.org; spf=pass (imf05.hostedemail.com: domain of gregkh@linuxfoundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752659014; a=rsa-sha256; cv=none; b=17DoIQwu+eD08xIPuBr41PEwhBNmmwdinLxmZvjcRqyfzRm1ZigkClKMD1Z6k74BCNLoER hnXCh+qJkSeW5DgTZyMhZ2dru3FA4nTS1vB1jGEcY8AwKXIZEF/GeZTowW842aJ3NZIRfk hHILaNemXY2CZFoalQ4oLaNFE6eDSRc= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=linuxfoundation.org header.s=korg header.b=QccxkNiH; dmarc=pass (policy=none) header.from=linuxfoundation.org; spf=pass (imf05.hostedemail.com: domain of gregkh@linuxfoundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1752659014; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=idh3sdBTJx8ELtmbGG9F8rLPgBN3eLJviroJ4FO4u+Y=; b=igy1UC/ah+VKOl5mtsrLsNAJIhKvxvfjSi3qrbqBJ7UR7R4ym9NQZjrDVsX/aKYng46iF9 ku5Nnae1ksi38sUmhpkTS1CXpxjNctcw+NmaWYJrDww9Dj8/c53F/irW4zuiX0GOAQq0Fw XVA2LmhSBagHyEEKbrWBAV7mbrHoDsU= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 541884373F; Wed, 16 Jul 2025 09:43:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27D82C4CEF0; Wed, 16 Jul 2025 09:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752659013; bh=q5LfttOSVPzCartXtZWejPzdbFBiNa7ERB5VCpk6jJw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QccxkNiHzqU3CbdaWh8pI3X9zIGdHfPtpPBsv2I/f8ke2IloGRiOuWsWwVyPJqjwm kqE3KFHjnMUgwtcxSnfjQZgOlc5l39L3q2Iey81EXDzttE0ZpmnIzhDIQyTobq3GuQ 1ZRqfoEY12f3dQdysOqxn6faTTM616N8B+BN7bN4= Date: Wed, 16 Jul 2025 11:43:30 +0200 From: Greg KH To: Jason Gunthorpe Cc: Mike Rapoport , 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, 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: <2025071602-ditch-danger-f5da@gregkh> References: <20250515182322.117840-1-pasha.tatashin@soleen.com> <20250515182322.117840-11-pasha.tatashin@soleen.com> <20250624-akzeptabel-angreifbar-9095f4717ca4@brauner> <20250714143443.GF1870174@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250714143443.GF1870174@ziepe.ca> X-Stat-Signature: i9a63confna56wiuy31khirmttczg3b5 X-Rspam-User: X-Rspamd-Queue-Id: A126E100009 X-Rspamd-Server: rspam02 X-HE-Tag: 1752659014-902883 X-HE-Meta: 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 PvTDxcCc NEIBrrL39wCjETxkMnGzSHHdjefJl84ZaHAlHNgJM8rKwRaAf+UNGR9IvEKlwxzqYqLMD5ivS30TDuOC2uWmo63+1Z0f56yEuy18S1zDUTXAQhaM2hYjN9/ieBbJJao1X09J1YSudR+KSoUfrp24rW1V0rDMB2QrbX3zBxqNeyn9iXy2dtqFxsiRwyYBFfuS8FFT/KeTHCp+FnvfNH4/r8LS8gKJku3DVcbSgPpsJCzvtoi2y19aPDXrA8JSeIo2VJbGmI7GuQHwyjF6SNX5CKOqy5ZCUY2O9mw8toRSuHOK15NyLTtQh4C05GkTTFJxJ5J+TLwPWJqsaHgscU4bndhvYdZEavX8Qig0gIBIzFFEy63iNdRkFztRguN/41jRkLGKFkQiYuLkTZBayvVE+MwZszzs0HN53CEy33pox1mAf2u1wRzO1R4wV9t3E1r4Ms+Pv 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 Mon, Jul 14, 2025 at 11:34:43AM -0300, Jason Gunthorpe wrote: > 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. Then use a special filesystem, and not sysfs. It's easy to embed a virtual filesystem in a driver, please do that instead. thanks, greg k-h