From nobody Mon Apr 6 20:10:53 2026 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 D70B6ECAAD3 for ; Sun, 4 Sep 2022 04:12:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229564AbiIDEMr (ORCPT ); Sun, 4 Sep 2022 00:12:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230320AbiIDEMh (ORCPT ); Sun, 4 Sep 2022 00:12:37 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8846A4AD5C for ; Sat, 3 Sep 2022 21:12:36 -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 148FFB80C9E for ; Sun, 4 Sep 2022 04:12:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 889B9C433D6; Sun, 4 Sep 2022 04:12:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662264753; bh=tu/uBFTcTkD8ciezaLIOud2OqZdulEjwj2vtD/px5uc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h3krUUwZyDHVYmtOAfdpwCbD3cNTV7riPHLvp+r5I/xkefZHN5pr/kebn6G7QHhCV xgvlp7TTcQ8G+wAk48cFInW/bzYJNPFjZi7ksEr+afZQIzLmsSRjnHhpsQOrjQ27PS SbotkMUUImvErJmgpf0ogxvq7BMk7TErbkA9sbM1vFTXTjolIkXHuiCpf4MJ+etlfG HbiqICGUfaciYjo+8+RFL5nzEEU8Gp2tRTeSCqTmgXU//EnFVAXJ6EkbelyzE0Vp5J H2TNwpbU+EBE+AQODjpb3YGU+J/AIG8FwUDpfB92rUHq0Z5biN0CBDySQa5qIGXYzJ lhYTGOyYqTArQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Tom Zanussi , Ingo Molnar , linux-kernel@vger.kernel.org Subject: [PATCH v5 2/6] tracing: Fix to check event_mutex is held while accessing trigger list Date: Sun, 4 Sep 2022 13:12:29 +0900 Message-Id: <166226474977.223837.1992182913048377113.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <166226473132.223837.9011128463174539022.stgit@devnote2> References: <166226473132.223837.9011128463174539022.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) Since the check_user_trigger() is called outside of RCU read lock, this list_for_each_entry_rcu() caused a suspicious RCU usage warning. # echo hist:keys=3Dpid > events/sched/sched_stat_runtime/trigger # cat events/sched/sched_stat_runtime/trigger [ 43.167032] [ 43.167418] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D [ 43.167992] WARNING: suspicious RCU usage [ 43.168567] 5.19.0-rc5-00029-g19ebe4651abf #59 Not tainted [ 43.169283] ----------------------------- [ 43.169863] kernel/trace/trace_events_trigger.c:145 RCU-list traversed i= n non-reader section!! ... However, this file->triggers list is safe when it is accessed under event_mutex is held. To fix this warning, adds a lockdep_is_held check to the list_for_each_entry_rcu(). Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_events_trigger.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_event= s_trigger.c index cb866c3141af..918730d74932 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -142,7 +142,8 @@ static bool check_user_trigger(struct trace_event_file = *file) { struct event_trigger_data *data; =20 - list_for_each_entry_rcu(data, &file->triggers, list) { + list_for_each_entry_rcu(data, &file->triggers, list, + lockdep_is_held(&event_mutex)) { if (data->flags & EVENT_TRIGGER_FL_PROBE) continue; return true;