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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85F12C433E0 for ; Sat, 23 May 2020 10:31:36 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id C9B67206DD for ; Sat, 23 May 2020 10:31:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=sakamocchi.jp header.i=@sakamocchi.jp header.b="H3rWb5HU"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="CcVRcc9i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C9B67206DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sakamocchi.jp Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18863-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 11548 invoked by uid 550); 23 May 2020 10:31:27 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 30383 invoked from network); 23 May 2020 07:59:15 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sakamocchi.jp; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm1; bh=K9bdneoooJ1uSBw5jkomBqz3iW0 HsoKgOxHBuN88dzA=; b=H3rWb5HUYcQn7iZXb7kBxoSo164u2D2hVvlNCeXfw33 vPfXrucVHEPaNFgPKynsNfLu9sswkct6TBU+ulxNIaw6VejbT3wIjZSh1SBgRWed 37G/3vgYwnuytM7AUt8VmRelj55JNfHGl1DFJBnkktNp8gbthsSgRqUD1vb3Dioo oApBMjnbaUmoQHmdsXR/FXiAtvFI3xc/C56alJZluumRtFOFuQWhJ6VtYXGn29mx /uHQLUxc7EcEWeJSmD0RVHQVwxL4y6E+vJ36WC4ktDt+GWzQYna8G67frcbar58V WkkaAGX9eKQ7ZdE0czbjq4KF00ZmXPj+KX9G9WSf7qA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=K9bdne oooJ1uSBw5jkomBqz3iW0HsoKgOxHBuN88dzA=; b=CcVRcc9iulo5FrFWsvMwNI lnO1f6CwgY494tKBtmumqn8rFALyNsIivbS9xjEuFDxNvieYN9l7bH8WRLr+piIR Hj1jylf3k9X9SMeOYOzEMKd1s/EJHu1VdQ7/+FqtPUVATE/KUoEHME8/ctLx+itm eagXQ48TrSjcTD6En5e10/SVYN8DPtqRQZIwzDFDZ6T4+ggwg+Z5pKCf5SwFjZNy H1xpeXO1XhBuis4MzAWZOClWQIJIggq4HU8TTMcNqQr+dMJbbRE/O5YaYggluu+v hkouwGdlZiV8+Gw6yhghDLUytmFQ+kUM8upUDnJlv3Gq1dPGRi5Cmr7Q6VFMCqQA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduhedruddugedguddvvdcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpeffhffvuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepvfgrkhgr shhhihcuufgrkhgrmhhothhouceoohdqthgrkhgrshhhihesshgrkhgrmhhotggthhhird hjpheqnecuggftrfgrthhtvghrnhephfefleekfeevgffhhfehudetkeeivdeuvdelgeej jefhffegkeffffdugfevudetnecuffhomhgrihhnpehgihhthhhusgdrtghomhdprghlsh grqdhprhhojhgvtghtrdhorhhgnecukfhppedukedtrddvfeehrdefrdehgeenucevlhhu shhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehoqdhtrghkrghshh hisehsrghkrghmohgttghhihdrjhhp X-ME-Proxy: Date: Sat, 23 May 2020 16:58:54 +0900 From: Takashi Sakamoto To: Greg KH Cc: Oscar Carter , stable , Kees Cook , Stefan Richter , Mauro Carvalho Chehab , Clemens Ladisch , Jaroslav Kysela , Takashi Iwai , kernel-hardening@lists.openwall.com, linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, alsa-devel@alsa-project.org, "Lev R . Oshvang ." Subject: Re: [PATCH v2] firewire: Remove function callback casts Message-ID: <20200523075854.GA170441@workstation> Mail-Followup-To: Greg KH , Oscar Carter , stable , Kees Cook , Stefan Richter , Mauro Carvalho Chehab , Clemens Ladisch , Jaroslav Kysela , Takashi Iwai , kernel-hardening@lists.openwall.com, linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, alsa-devel@alsa-project.org, "Lev R . Oshvang ." References: <20200519173425.4724-1-oscar.carter@gmx.com> <20200520061624.GA25690@workstation> <20200522174308.GB3059@ubuntu> <20200523061033.GB3131938@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200523061033.GB3131938@kroah.com> Hi Greg, On Sat, May 23, 2020 at 08:10:33AM +0200, Greg KH wrote: > On Fri, May 22, 2020 at 07:43:08PM +0200, Oscar Carter wrote: > > Hi, > > > > On Wed, May 20, 2020 at 03:16:24PM +0900, Takashi Sakamoto wrote: > > > Hi, > > > > > > I'm an author of ALSA firewire stack and thanks for the patch. I agree with > > > your intention to remove the cast of function callback toward CFI build. > > > > > > Practically, the isochronous context with FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL > > > is never used by in-kernel drivers. Here, I propose to leave current > > > kernel API (fw_iso_context_create() with fw_iso_callback_t) as is. > > If it's not used by anyone, why is it still there? Can't we just delete > it? For this patchset, I followed to the theory to keep backward compatibility when adding any change, and it's what I'd like to discuss. The isoc context of multichannel mode is also available for userspace applications, and libhinoko[1] uses it. In a point of backward compatibility for userspace, we can't delete the mode. (Practically, the mode is useful for the purpose of packet sniffing in bus and helpful to my work for development of ALSA firewire stack[2].) On the other hand, there's no unit driver to use the mode in upstream kernel. It's unlikely to use the mode for unit driver since the mode is not specific to unit functionality. In my opinion, it's reasonable to lose backward compatibility slightly by hiding the multichannel mode from in-kernel unit driver. I'll post v2 patchset later and I'd like you to merge them if no objections from the others for the loss of backward compatibility. [1] https://github.com/takaswie/libhinoko [2] https://mailman.alsa-project.org/pipermail/alsa-devel/2019-April/147862.html Regards Takashi Sakamoto