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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BDFBC433EF for ; Fri, 18 Mar 2022 16:31:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237533AbiCRQcp (ORCPT ); Fri, 18 Mar 2022 12:32:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239196AbiCRQcl (ORCPT ); Fri, 18 Mar 2022 12:32:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 974451AE625; Fri, 18 Mar 2022 09:31:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9FC09B82475; Fri, 18 Mar 2022 16:31:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58498C340EC; Fri, 18 Mar 2022 16:31:00 +0000 (UTC) Date: Fri, 18 Mar 2022 12:30:58 -0400 From: Steven Rostedt To: Sven Schnelle Cc: Ritesh Harjani , linux-ext4@vger.kernel.org, Jan Kara , "Theodore Ts'o" , Harshad Shirwadkar , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@kernel.org Subject: Re: [PATCHv3 02/10] ext4: Fix ext4_fc_stats trace point Message-ID: <20220318123058.348938b1@gandalf.local.home> In-Reply-To: <20220317143938.745e1420@gandalf.local.home> References: <20220317143938.745e1420@gandalf.local.home> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, 17 Mar 2022 14:39:38 -0400 Steven Rostedt wrote: > [ here I wanted to add a patch, but I haven't figured out the best way to > fix it yet. ] Care to try this patch? -- Steve diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 7b558c72f595..e11e167b7809 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -40,6 +40,14 @@ static LIST_HEAD(ftrace_generic_fields); static LIST_HEAD(ftrace_common_fields); static bool eventdir_initialized; +static LIST_HEAD(module_strings); + +struct module_string { + struct list_head next; + struct module *module; + char *str; +}; + #define GFP_TRACE (GFP_KERNEL | __GFP_ZERO) static struct kmem_cache *field_cachep; @@ -2643,14 +2651,40 @@ static void update_event_printk(struct trace_event_call *call, } } +static void add_str_to_module(struct module *module, char *str) +{ + struct module_string *modstr; + + modstr = kmalloc(sizeof(*modstr), GFP_KERNEL); + + /* + * If we failed to allocate memory here, then we'll just + * let the str memory leak when the module is removed. + * If this fails to allocate, there's worse problems than + * a leaked string on module removal. + */ + if (WARN_ON_ONCE(!modstr)) + return; + + modstr->module = module; + modstr->str = str; + + list_add(&modstr->next, &module_strings); +} + static void update_event_fields(struct trace_event_call *call, struct trace_eval_map *map) { struct ftrace_event_field *field; struct list_head *head; char *ptr; + char *str; int len = strlen(map->eval_string); + /* Dynamic events should never have field maps */ + if (WARN_ON_ONCE(call->flags & TRACE_EVENT_FL_DYNAMIC)) + return; + head = trace_get_fields(call); list_for_each_entry(field, head, link) { ptr = strchr(field->type, '['); @@ -2664,9 +2698,26 @@ static void update_event_fields(struct trace_event_call *call, if (strncmp(map->eval_string, ptr, len) != 0) continue; + str = kstrdup(field->type, GFP_KERNEL); + if (WARN_ON_ONCE(!str)) + return; + ptr = str + (ptr - field->type); ptr = eval_replace(ptr, map, len); /* enum/sizeof string smaller than value */ - WARN_ON_ONCE(!ptr); + if (WARN_ON_ONCE(!ptr)) { + kfree(str); + continue; + } + + /* + * If the event is part of a module, then we need to free the string + * when the module is removed. Otherwise, it will stay allocated + * until a reboot. + */ + if (call->module) + add_str_to_module(call->module, str); + + field->type = str; } } @@ -2893,6 +2944,7 @@ static void trace_module_add_events(struct module *mod) static void trace_module_remove_events(struct module *mod) { struct trace_event_call *call, *p; + struct module_string *modstr, *m; down_write(&trace_event_sem); list_for_each_entry_safe(call, p, &ftrace_events, list) { @@ -2901,6 +2953,14 @@ static void trace_module_remove_events(struct module *mod) if (call->module == mod) __trace_remove_event_call(call); } + /* Check for any strings allocade for this module */ + list_for_each_entry_safe(modstr, m, &module_strings, next) { + if (modstr->module != mod) + continue; + list_del(&modstr->next); + kfree(modstr->str); + kfree(modstr); + } up_write(&trace_event_sem); /*