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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 E2A2EC433E6 for ; Wed, 17 Mar 2021 10:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C14764F20 for ; Wed, 17 Mar 2021 10:26:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229918AbhCQK0X (ORCPT ); Wed, 17 Mar 2021 06:26:23 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:14362 "EHLO szxga07-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229864AbhCQK0A (ORCPT ); Wed, 17 Mar 2021 06:26:00 -0400 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4F0mTp2N28z9s02; Wed, 17 Mar 2021 18:23:58 +0800 (CST) Received: from ubuntu1804.huawei.com (10.67.174.174) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.498.0; Wed, 17 Mar 2021 18:25:40 +0800 From: Li Huafei To: , , CC: , , , , Subject: [PATCH 1/2] ftrace: Update ftrace_ops->next pointer with rcu_assign_pointer() Date: Wed, 17 Mar 2021 18:25:28 +0800 Message-ID: <20210317102529.226734-2-lihuafei1@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210317102529.226734-1-lihuafei1@huawei.com> References: <20210317102529.226734-1-lihuafei1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.174.174] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The unregistered ftrace_ops may be freed by the caller, so we should use rcu_assign_pointer() in remove_ftrace_ops() to remove the ftrace_ops, which ensures that no more users will reference the ftrace_ops after synchronize_rcu() is called. Signed-off-by: Li Huafei --- kernel/trace/ftrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 4d8e35575549..2e315a145d20 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -282,7 +282,7 @@ static int remove_ftrace_ops(struct ftrace_ops __rcu **list, lockdep_is_held(&ftrace_lock)) == ops && rcu_dereference_protected(ops->next, lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) { - *list = &ftrace_list_end; + rcu_assign_pointer(*list, &ftrace_list_end); return 0; } @@ -293,7 +293,7 @@ static int remove_ftrace_ops(struct ftrace_ops __rcu **list, if (*p != ops) return -1; - *p = (*p)->next; + rcu_assign_pointer(*p, (*p)->next); return 0; } -- 2.17.1