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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 CAAE6C73C53 for ; Tue, 9 Jul 2019 16:10:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D77C2171F for ; Tue, 9 Jul 2019 16:10:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562688647; bh=sZeMD4oVQwPrdMKxyv7QW1fVkzIcKk8DIBHqtvwcWPs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=OTUXQZ1k40RYtUdcDdIDtY3j6bsZgF2xdXUlutVpa82X9ZXBfKVW5UJniSfLuWGUS 18rA1IFlZuZUcaXEOakU5ciOfsXUIOthUbZdrSZ/5+tPjr//T8amIJoEYV4KSn+1+o lZdBl7OdKy9cm+zqjs9S7RojqmiQLd1BajSo96I4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726660AbfGIQKq (ORCPT ); Tue, 9 Jul 2019 12:10:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:46494 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726060AbfGIQKq (ORCPT ); Tue, 9 Jul 2019 12:10:46 -0400 Received: from linux-8ccs (ip5f5adbef.dynamic.kabel-deutschland.de [95.90.219.239]) (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 67EB720656; Tue, 9 Jul 2019 16:10:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562688645; bh=sZeMD4oVQwPrdMKxyv7QW1fVkzIcKk8DIBHqtvwcWPs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ar5tnU95snb3l/W5KYlNQP9YQ1KcXM5zwJ7JQjzNWOjLwiCytDHRWgQyjFt0Oi0GP IF+CW2oXBDXZem/WACI2CXhMNKEaXo3h4WE9cSLKzxIpjD3daJ+RWmC4r7aqgFuYkn T7jI/n2nFLhON2jr2Ygkg+lAcr+VSrOnAKF19Nwc= Date: Tue, 9 Jul 2019 18:10:39 +0200 From: Jessica Yu To: Zhiqiang Liu Cc: rusty@rustcorp.com.au, kay.sievers@vrfy.org, clabbe.montjoie@gmail.com, LKML , wangxiaogang3@huawei.com, zhoukang7@huawei.com, Mingfangsen Subject: Re: [PATCH v2] module: add usage links when calling ref_module func Message-ID: <20190709161039.GA3501@linux-8ccs> References: <4fec6c3b-03b8-dd57-4009-99431105a8a5@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <4fec6c3b-03b8-dd57-4009-99431105a8a5@huawei.com> X-OS: Linux linux-8ccs 4.12.14-lp150.12.28-default x86_64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +++ Zhiqiang Liu [03/07/19 10:09 +0800]: >From: Zhiqiang Liu > >Users can call ref_module func in their modules to construct >relationships with other modules. However, the holders >'/sys/module//holders' of the target module donot include >the users` module. So lsmod command misses detailed info of 'Used by'. > >When load module, the process is given as follows, >load_module() > -> mod_sysfs_setup() > -> add_usage_links > -> do_init_module > -> mod->init() > >add_usage_links func creates holders of target modules linking to >this module. If ref_module is called in mod->init() func, the usage >links cannot be added. > >Here, we will add usage link of a to b's holder_dir. > >V1->V2: >- remove incorrect Fixes tag >- fix error handling of sysfs_create_link as suggested by Jessica Yu > >Signed-off-by: Zhiqiang Liu >Suggested-by: Jessica Yu >Reviewed-by: Kang Zhou >--- > kernel/module.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > >diff --git a/kernel/module.c b/kernel/module.c >index 80c7c09584cf..672abce2222c 100644 >--- a/kernel/module.c >+++ b/kernel/module.c >@@ -837,25 +837,26 @@ static int already_uses(struct module *a, struct module *b) > * 'b' can walk the list to see who sourced them), and of 'a' > * targets (so 'a' can see what modules it targets). > */ >-static int add_module_usage(struct module *a, struct module *b) >+static struct module_use *add_module_usage(struct module *a, struct module *b) > { > struct module_use *use; > > pr_debug("Allocating new usage for %s.\n", a->name); > use = kmalloc(sizeof(*use), GFP_ATOMIC); > if (!use) >- return -ENOMEM; >+ return NULL; > > use->source = a; > use->target = b; > list_add(&use->source_list, &b->source_list); > list_add(&use->target_list, &a->target_list); >- return 0; >+ return use; > } > > /* Module a uses b: caller needs module_mutex() */ > int ref_module(struct module *a, struct module *b) > { >+ struct module_use *use; > int err; > > if (b == NULL || already_uses(a, b)) >@@ -866,9 +867,18 @@ int ref_module(struct module *a, struct module *b) > if (err) > return err; > >- err = add_module_usage(a, b); >+ use = add_module_usage(a, b); >+ if (!use) { >+ module_put(b); >+ return -ENOMEM; >+ } >+ >+ err = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name); Sigh. This ultimately doesn't work because in load_module(), we use ref_module() in resolve_symbol(), and mod->mkobj.kobj doesn't get initialized until mod_sysfs_init(), which happens much later in load_module(). So what happens is that the ref_module(mod, owner) call in resolve_symbol() returns an error because sysfs_create_link() fails here. We could *maybe* move sysfs initialization earlier in load_module() but that is an entirely untested idea and I would need to think about that more. > if (err) { > module_put(b); >+ list_del(&use->source_list); >+ list_del(&use->target_list); >+ kfree(use); > return err; > } > return 0; >-- >2.19.1 >