From nobody Tue Apr 7 14:51:55 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 E4A1AECAAD1 for ; Sat, 27 Aug 2022 04:03:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232468AbiH0EDf (ORCPT ); Sat, 27 Aug 2022 00:03:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237359AbiH0EDa (ORCPT ); Sat, 27 Aug 2022 00:03:30 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64253E3C03 for ; Fri, 26 Aug 2022 21:03:29 -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 dfw.source.kernel.org (Postfix) with ESMTPS id C82EE61E16 for ; Sat, 27 Aug 2022 04:03:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DAEBC433D6; Sat, 27 Aug 2022 04:03:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661573008; bh=tu/uBFTcTkD8ciezaLIOud2OqZdulEjwj2vtD/px5uc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sOgO/3jr3dCmERi87hkG3jw3yqWXJRMOFDLMR8bRfcR7ryZdwafXXt8Z5rHLtZTFx uh/P4dgzsTRlhv7pQVKMmkwEJSHiMGBPD/2Ci0hqca8T9q1s935XHo3PfalUbLWU1I tD2nzUxCHmjoXLIV+ISm1AROjGYb4kUJnsqU2T+btP0WBFTBRO0BNfBS4I4Gi9ieUW xo4F9yFYUsF2kr77G8806cl/TXGuVmuS9ZU9YVv0heXB/9nbmSEtEhWuhPwFfqTPHy DiajW+Nvn1xAB0oS3Cy330pmQAcS8RgCbs3hAv6hH1HADfb5hN9T8zScIIb9Lz/IbG ZwHA85YqOIeuA== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Tom Zanussi , Ingo Molnar , linux-kernel@vger.kernel.org Subject: [PATCH v4 2/5] tracing: Fix to check event_mutex is held while accessing trigger list Date: Sat, 27 Aug 2022 13:03:24 +0900 Message-Id: <166157300435.348924.14755234601275629058.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <166157298537.348924.2537162090505397377.stgit@devnote2> References: <166157298537.348924.2537162090505397377.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;