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=-16.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 F194CC4332B for ; Tue, 2 Feb 2021 12:15:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D46E064F6D for ; Tue, 2 Feb 2021 12:15:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230193AbhBBMPG (ORCPT ); Tue, 2 Feb 2021 07:15:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230430AbhBBMOl (ORCPT ); Tue, 2 Feb 2021 07:14:41 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7750FC0613ED; Tue, 2 Feb 2021 04:14:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=XZTC5SIMvJdOEqgDU+iIbCSxaEGoFe1SHGfByrwd00g=; b=S3XLWVvOyKvKUYYqHqqt+ziNGW yJYK/kqQMGT1QCR9/vos9RUmeKJPxeHpkcazip+Yknz0VlFHQAFL8LW43Q49lmNcN7Ew5AgKEsqTY DW36OZVvxv8Mp+UJpRx+eVcgZo4eXZ9UA2dKuKGYj9b9a3m/gS+Xg6ETWat5E7Y6AjUj21wztjsf7 ez1Xef7D21kx0aCFnYCwMi7D+2PBLd8iQdKg7Osu6/TkXJhl5Lt394F5YZqRVxek29x+V6lr3LFYz ovUQ1mEvxvJ2zZEQMcjIbUpCXkzLL7KzBVOpU+KSsY4pmesHVlECQFxfhk0PZMz+WLjSGyDCVw+Zf R5s+Snwg==; Received: from [2001:4bb8:198:6bf4:7f38:755e:a6e0:73e9] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l6uYz-00FALZ-GH; Tue, 02 Feb 2021 12:13:46 +0000 From: Christoph Hellwig To: Frederic Barrat , Andrew Donnellan , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Jessica Yu , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence Cc: Masahiro Yamada , Michal Marek , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, dri-devel@lists.freedesktop.org, live-patching@vger.kernel.org, linux-kbuild@vger.kernel.org Subject: [PATCH 04/13] module: use RCU to synchronize find_module Date: Tue, 2 Feb 2021 13:13:25 +0100 Message-Id: <20210202121334.1361503-5-hch@lst.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210202121334.1361503-1-hch@lst.de> References: <20210202121334.1361503-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org Allow for a RCU-sched critical section around find_module, following the lower level find_module_all helper, and switch the two callers outside of module.c to use such a RCU-sched critical section instead of module_mutex. Signed-off-by: Christoph Hellwig Reviewed-by: Petr Mladek Acked-by: Miroslav Benes --- include/linux/module.h | 2 +- kernel/livepatch/core.c | 5 +++-- kernel/module.c | 1 - kernel/trace/trace_kprobe.c | 4 ++-- 4 files changed, 6 insertions(+), 6 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 7a0bcb5b1ffccd..a64aa84d1b182c 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -586,7 +586,7 @@ static inline bool within_module(unsigned long addr, const struct module *mod) return within_module_init(addr, mod) || within_module_core(addr, mod); } -/* Search for module by name: must hold module_mutex. */ +/* Search for module by name: must be in a RCU-sched critical section. */ struct module *find_module(const char *name); struct symsearch { diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index f76fdb9255323d..262cd9b003b9f0 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include "core.h" #include "patch.h" @@ -57,7 +58,7 @@ static void klp_find_object_module(struct klp_object *obj) if (!klp_is_module(obj)) return; - mutex_lock(&module_mutex); + rcu_read_lock_sched(); /* * We do not want to block removal of patched modules and therefore * we do not take a reference here. The patches are removed by @@ -74,7 +75,7 @@ static void klp_find_object_module(struct klp_object *obj) if (mod && mod->klp_alive) obj->mod = mod; - mutex_unlock(&module_mutex); + rcu_read_unlock_sched(); } static bool klp_initialized(void) diff --git a/kernel/module.c b/kernel/module.c index 981302f616b411..6772fb2680eb3e 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -668,7 +668,6 @@ static struct module *find_module_all(const char *name, size_t len, struct module *find_module(const char *name) { - module_assert_mutex(); return find_module_all(name, strlen(name), false); } diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index e6fba1798771b4..3137992baa5e7a 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -124,9 +124,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) if (!p) return true; *p = '\0'; - mutex_lock(&module_mutex); + rcu_read_lock_sched(); ret = !!find_module(tk->symbol); - mutex_unlock(&module_mutex); + rcu_read_unlock_sched(); *p = ':'; return ret; -- 2.29.2