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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no 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 10760C4361B for ; Mon, 14 Dec 2020 23:32:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C393422510 for ; Mon, 14 Dec 2020 23:32:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726410AbgLNXcX (ORCPT ); Mon, 14 Dec 2020 18:32:23 -0500 Received: from relay1-d.mail.gandi.net ([217.70.183.193]:44821 "EHLO relay1-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726407AbgLNXcV (ORCPT ); Mon, 14 Dec 2020 18:32:21 -0500 X-Originating-IP: 193.27.14.10 Received: from orivej.orivej.org (unknown [193.27.14.10]) (Authenticated sender: orivej@orivej.org) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id C32A6240003; Mon, 14 Dec 2020 23:31:36 +0000 (UTC) Date: Mon, 14 Dec 2020 23:31:34 +0000 From: Orivej Desh To: Sebastian Andrzej Siewior Cc: LKML , Thomas Gleixner , Steven Rostedt , linux-rt-users@vger.kernel.org, Peter Zijlstra , Brian Behlendorf Subject: Re: sched: exporting linux-rt migrate_disable for ZFS Message-ID: <20201214233134.06f12bbb@orivej.orivej.org> In-Reply-To: <20201214123302.w2bem7tlb664jdvx@linutronix.de> References: <20201208212841.694b3022@orivej.orivej.org> <20201214123302.w2bem7tlb664jdvx@linutronix.de> X-Mailer: Claws Mail 3.99.0 (GTK+ 3.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org * Sebastian Andrzej Siewior [2020-12-14] > On 2020-12-08 23:58:27 [+0000], Orivej Desh wrote: > > With sched-Add-migrate_disable.patch first released in v5.9-rc8-rt14 [1] > > linux-rt defines functions migrate_disable and migrate_enable. > > They are used in linux headers in various macros and static inline > > functions, and in particular in kmap_atomic and kunmap_atomic. > > The latter are needed by ZFS which currently fails to build against > > 5.9-rt [2] because these functions are exported with EXPORT_SYMBOL_GPL. > > Could you export them with EXPORT_SYMBOL instead? > > This is out of my jurisdiction, so just a few notes: > - v5.9 is out of maintenance. Be careful. Thanks! I have noticed a bug with usb-storage (using smp_processor_id in preemptible code) in 5.9.1-rt20 thas has been fixed in 5.10-rt17. > - We don't export symbols for out-of-tree modules. The issue is that in the vanilla kernel these two functions are available as macros that expand into EXPORT_SYMBOL function calls (kunmap_atomic_high, etc.). If I am not mistaken the kernel is generally supposed to keep the API made available to non-GPL modules still available, for example here https://lwn.net/Articles/171838/ : "When GPL-only exports were first added to the kernel, they went in with the understanding that only new symbols would be tagged GPL-only. The current module interface - while always subject to change - was not to have symbols withdrawn arbitrarily." The current rt patch has this effect: it makes non-GPL API of the vanilla kernel GPL-only.