From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8304C17C211; Thu, 29 May 2025 21:07:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748552864; cv=none; b=SKP7Rk3jgGmBVsf6BPZfw+cMhOIXvEn+RxSSQIJGN8oto8F0tCqv8zpCE6tz3pH7du/EsC/3dHAAekuJ0EkhSB+FADhVv1Cp4/x4enbGY9nuaLdYrY0IODIwymjgHAoWJkPk5Qdwj/cftCShkMmpO0cFoMDKDYLcHB0HQhGcs0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748552864; c=relaxed/simple; bh=9lwVrDAjs/lkkEAfim6H2iCHnFpOqWZjGv1g1H2UR54=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=KwaNbx1AFzVMLSjdHi5sttJ/5c/JVy3zfLZcBwR7CJvo6P77ft2ZtKT0FMuir5qTelBsYRCUNxrQe0AqFwqnWt8McrJIUaGxsG41ZJnUjCb6Wm+TnFfT/VoQGl/TKW40aEj/VI+DizLO/HeKlY1U8khIzFR/BxkZN6n8e1Wix/Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bZZSuhmK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bZZSuhmK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA6FAC4AF0C; Thu, 29 May 2025 21:07:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1748552863; bh=9lwVrDAjs/lkkEAfim6H2iCHnFpOqWZjGv1g1H2UR54=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=bZZSuhmKMa+ge/xdHma3i0suzM815Bf2D4x+BYt+i34JtRs/kmCqXpRdGhEvRds4S ZmEwUURQQDjoPF9bLAvlZkEYV4LdWskLOflZ7bjWO0NGIV9gYVfLRxhj0eTiIPzjCU wulMkOReCHVq1Wxmonyd2VzGykKYQ7mrD9L7hz5dlF9ZkqfoS5qn3sP7QV868xTVrw fsDOA90TbRsRqQ+CmTtUL9Cnh82r24Ov/E/2oJOfQRkX1ONPJrvob5vedbAKESI5EK qp+kaZj/CaO/SLJopwuoXT3AtLMmqmJxFqAQvrqFJ3rcRJR6qLx/FQMpU1dBLGcbcD 8EhINM1lfyXeQ== Received: by mail-qt1-f171.google.com with SMTP id d75a77b69052e-48d71b77cc0so15867601cf.1; Thu, 29 May 2025 14:07:43 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCUYfjL2+RuYSooKtSUSLlhYZKdk0cJQUi2mMAsu17HzC/fiTKpis9pZ9OtzWcLiMqrE2/XnIPjU8sFJ7ZhV@vger.kernel.org, AJvYcCUkuppWCgwurLjJlP1fJXvUOgZWj9Vr6Z56CrymB2O+a0BUtk41H5lhljROpbkRoycG11Zi6kumAe7n1V8VwHygz7ByGiw5@vger.kernel.org, AJvYcCWbMm6l4PaCcj4ZFB5ZiRbsG8szagoMMwC96xoK3gxmld8336aA6DKjUvmPVisAS4VM3fw=@vger.kernel.org, AJvYcCXH9Y7TPdPtw7kyhvmoFULmu4kqY0QgLiDmGovXS7PouRYCvoQGc3AfoCDGcXHnxVM0sMGcyG9g7QMruLoyNg==@vger.kernel.org X-Gm-Message-State: AOJu0YxmMmypGUWIsdZGt+01WwMQakJy9cTzpDeGQNKgFe026ZHJqvmx AWzJbH71rw29XuVcEKm0HdDAUHo3rMgW8fW2BrkLHyOHpIxcSCS/a9MN9IoJGrVYnbggSRWnaDl JBdWm1clpS44ve1MOQJjTBwU5JIW2blc= X-Google-Smtp-Source: AGHT+IGw4pMchJ96DZc80mIXOTOvp7NLuynoTZX9jfg2YvO62Aip44MiKW0pjVLexS09OxgB8FMIx+eE6NshgaPUNGE= X-Received: by 2002:a05:622a:40c5:b0:48a:2429:9dc1 with SMTP id d75a77b69052e-4a440020affmr17445751cf.9.1748552862928; Thu, 29 May 2025 14:07:42 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250528222623.1373000-1-song@kernel.org> <20250528222623.1373000-4-song@kernel.org> <20250528223724.GE2023217@ZenIV> <20250529173810.GJ2023217@ZenIV> <20250529183536.GL2023217@ZenIV> <20250529201551.GN2023217@ZenIV> In-Reply-To: <20250529201551.GN2023217@ZenIV> From: Song Liu Date: Thu, 29 May 2025 14:07:31 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: AX0GCFv7sIxT-gOoEHzHaCe2UgQwTNnXO5Ui6eVKQasQUvClMf-PLOS5PhBxXHA Message-ID: Subject: Re: [PATCH bpf-next 3/4] bpf: Introduce path iterator To: Al Viro Cc: Jan Kara , bpf@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@meta.com, andrii@kernel.org, eddyz87@gmail.com, ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, brauner@kernel.org, kpsingh@kernel.org, mattbobrowski@google.com, amir73il@gmail.com, repnop@google.com, jlayton@kernel.org, josef@toxicpanda.com, mic@digikod.net, gnoack@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, May 29, 2025 at 1:15=E2=80=AFPM Al Viro w= rote: > > On Thu, May 29, 2025 at 12:46:00PM -0700, Song Liu wrote: > > > > Basically, you are creating a spot we will need to watch very careful= ly > > > from now on. And the rationale appears to include "so that we could > > > expose that to random out-of-tree code that decided to call itself LS= M", > > > so pardon me for being rather suspicious about the details. > > > > No matter what we call them, these use cases exist, out-of-tree or > > in-tree, as BPF programs or kernel modules. We are learning from > > Landlock here, simply because it is probably the best way to achieve > > this. > > If out-of-tree code breaks from something we do kernel-side, it's the > problem of that out-of-tree code. You are asking for a considerable > buy-in, without even bothering to spell out what it is that we are > supposed to care about supporting. > > If you want cooperation, explain what is needed, and do it first, so that > there's no goalpost shifting afterwards. We have made it very clear what is needed now: an iterator that iterates towards the root. This has been discussed in LPC [1] and LSF/MM/BPF [2]. We don't know what might be needed in the future. That's why nothing is shared. If the problem is that this code looks extendible, we sure can remove it for now. But we cannot promise there will never be use cases that could benefit from a slightly different path iterator. Either way, if = we are adding/changing anything to the path iterator, you will always be CC'ed. You are always welcome to NAK anything if there is real issue with the code being developed. Thanks, Song [1] https://lpc.events/event/18/contributions/1940/ [2] https://lwn.net/Articles/1018493/