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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D88FAC3A5A5 for ; Thu, 5 Sep 2019 11:16:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B301C22CF5 for ; Thu, 5 Sep 2019 11:16:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567682188; bh=+Ngi9GoneR0+xaQyOFn0Cdw5Tsg/+FcNM58Ucnjchoo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=GCO8fNYWGZsXyE/jLhZ92W28AEHo+JN66PGX74DoHY7I8FQDz6xoCwquZ4M+WK67r 28+mtF3zEJHxl1u7t3xwMKmpjr2ulLNLemR7l21t3t7CfRYcuuTbhaQGHS9g68LiSm hvzRZLRTSMdOf1SGAzZMp1WDw3qNrPRIGCyfyi6o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732714AbfIELQZ (ORCPT ); Thu, 5 Sep 2019 07:16:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:55672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732604AbfIELQY (ORCPT ); Thu, 5 Sep 2019 07:16:24 -0400 Received: from linux-8ccs (charybdis-ext.suse.de [195.135.221.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 957E321883; Thu, 5 Sep 2019 11:16:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567682183; bh=+Ngi9GoneR0+xaQyOFn0Cdw5Tsg/+FcNM58Ucnjchoo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pU2eFvW5HfenoH+To4/oSVkLeQI2FBOiG5hX1GqEMy1b2Q7w9d9+tL2UdeK2BQd2Q kNSR8x789mrQCNe9TlydGmgY+MP7FDdIqE1ojxROLWqkHD5z32yFDTgxBUeLh/7Hbe M4/KPgLKqNi6eHRn+vWGYTSJ9i9a6+NdeQS0znDE= Date: Thu, 5 Sep 2019 13:16:17 +0200 From: Jessica Yu To: Arnd Bergmann Cc: Matthew Dharm , Guenter Roeck , Masahiro Yamada , Matthias Maennich , Linux Kernel Mailing List , "Cc: Android Kernel" , Greg Kroah-Hartman , "Joel Fernandes (Google)" , Lucas De Marchi , Martijn Coenen , Sandeep Patil , Will Deacon , Linux Kbuild mailing list , linux-modules@vger.kernel.org, linux-usb , USB Mass Storage on Linux , LINUXWATCHDOG Subject: Re: [usb-storage] Re: [PATCH v4 12/12] RFC: watchdog: export core symbols in WATCHDOG_CORE namespace Message-ID: <20190905111617.GB27788@linux-8ccs> References: <20180716122125.175792-1-maco@android.com> <20190903150638.242049-1-maennich@google.com> <20190903150638.242049-13-maennich@google.com> <20190903161045.GA22754@roeck-us.net> <20190905104147.GA27788@linux-8ccs> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: X-OS: Linux linux-8ccs 4.12.14-lp150.12.61-default x86_64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org +++ Arnd Bergmann [05/09/19 12:52 +0200]: >On Thu, Sep 5, 2019 at 12:41 PM Jessica Yu wrote: >> +++ Matthew Dharm [04/09/19 09:16 -0700]: >> >On Wed, Sep 4, 2019 at 5:12 AM Guenter Roeck wrote: > >> >HOWEVER, I have one question: If these patches are included, and >> >someone wants to introduce a bit of code which needs to use two >> >symbols from different namespaces but with the same name, can that be >> >done? That is, if driver A has symbol 'foo' and driver B has symbol >> >'foo' (both in their respective namespaces), and driver C wants to use >> >A.foo and B.foo, can that be supported? >> >> As of now, we currently don't support this - modpost will warn if a >> symbol is exported more than once (across modules + vmlinux), and the >> module loader currently assumes exported symbol names are unique. Do >> you have a concrete use case? If there is a strong need for this, I >> don't think it'd be too hard to implement. > >I think what would prevent this from working in general is that having >two modules with the same exported symbol in different namespaces >won't link if you try to build both modules into the kernel itself. > > Arnd Ah yeah, you are right. I only tried building an identically named exported symbol in a module and in the kernel, and there I got away with a modpost warning. But this breaks when building the module into the kernel, so I guess this is out of the question. Thanks, Jessica