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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 548A8C433E3 for ; Tue, 28 Jul 2020 17:26:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 354CA20829 for ; Tue, 28 Jul 2020 17:26:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731975AbgG1R0d (ORCPT ); Tue, 28 Jul 2020 13:26:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:42694 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731684AbgG1R0c (ORCPT ); Tue, 28 Jul 2020 13:26:32 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 E5D742078E; Tue, 28 Jul 2020 17:26:31 +0000 (UTC) Date: Tue, 28 Jul 2020 13:26:30 -0400 From: Steven Rostedt To: Chengming Zhou Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, songmuchun@bytedance.com Subject: Re: [External] Re: [PATCH 1/2] ftrace: clear module from hash of all ftrace ops Message-ID: <20200728132630.678f94f7@oasis.local.home> In-Reply-To: <557fa115-1247-e058-4a18-e73f6fb7d636@bytedance.com> References: <20200728102720.46837-1-zhouchengming@bytedance.com> <20200728085320.6b04e03f@oasis.local.home> <557fa115-1247-e058-4a18-e73f6fb7d636@bytedance.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 29 Jul 2020 00:59:33 +0800 Chengming Zhou wrote: > > i.e. > > > > # echo some_module_function > set_ftrace_filter > > # rmmod module_with_that_function > > # insmod module_with_same_address_of_function > > # echo function > current_tracer > > > > Now the tr->ops->hash would still have the function of the original > > module. > > I thought all ftrace_ops has non empty func_hash are on the ftrace > global list... Nope, the two are disjoint. > > Well, so I just leave this function unmodified. > > Just call that new function register_ftrace_ops_hash() from > ftrace_release_mod. I would say to have anything that uses one of the ftrace_set_filter/notrace* functions, to also register itself for module removal. register_ftrace_mod_removal(struct ftrace_ops *ops); and then also have a unregister_ftrace_mod_removal() as there needs to be a way to remove it from the list before the ops gets freed. Then these functions would add the ops to a list, and this list is traversed to remove modules. The trace_arrays can register their ops too, so you can update that function. -- Steve > > Thanks! > > > > > Either have all owners of ftrace_ops handle this case, or add a helper > > function to handle it for them. But using ftarce_ops_list is the wrong > > place to do it. > > > > -- Steve > > > > > >> + mutex_lock(&ftrace_lock); > >> + > >> + do_for_each_ftrace_op(op, ftrace_ops_list) { > >> + if (!op->func_hash) > >> continue; > >> - mutex_lock(&tr->ops->func_hash->regex_lock); > >> - clear_mod_from_hash(pg, tr->ops->func_hash->filter_hash); > >> - clear_mod_from_hash(pg, tr->ops->func_hash->notrace_hash); > >> - mutex_unlock(&tr->ops->func_hash->regex_lock); > >> - } > >> - mutex_unlock(&trace_types_lock); > >> + mutex_lock(&op->func_hash->regex_lock); > >> + clear_mod_from_hash(pg, op->func_hash->filter_hash); > >> + clear_mod_from_hash(pg, op->func_hash->notrace_hash); > >> + mutex_unlock(&op->func_hash->regex_lock); > >> + } while_for_each_ftrace_op(op); > >> + > >> + mutex_unlock(&ftrace_lock); > >> } > >> > >> static void ftrace_free_mod_map(struct rcu_head *rcu)