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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 59059C33C9B for ; Tue, 7 Jan 2020 21:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29DCE2080A for ; Tue, 7 Jan 2020 21:17:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431826; bh=GGD7cMCYVXparBQreXzD6AIEl/w57wcCsy3znaKzyhc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Hd4ESqmYpiM9Wi+NTNknbGvmDf+V7XEb9e/6HXJl66flTWd3g8FscuLKCw+g9IKqs OAa9x7a3qtWIXsJOlRe7GcNojtVSYiXIAT/wR9AkB+hsEMetzQST2j1MlLpNBBwaoj c0aAoH6VeR5AepoX+R3VnR/D1fa+BmvWEBM+/z2k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727210AbgAGVRB (ORCPT ); Tue, 7 Jan 2020 16:17:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:55608 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729381AbgAGVG2 (ORCPT ); Tue, 7 Jan 2020 16:06:28 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 E7BA12087F; Tue, 7 Jan 2020 21:06:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431187; bh=GGD7cMCYVXparBQreXzD6AIEl/w57wcCsy3znaKzyhc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KAWtDEsVmUaOPkI0nF+TBmZq6ui3ig5sjjYOaVo3Sc4un0jiwphpPJMfGM85m53XO fYvuRSo/mqcmTScEPauwXE8nnC3JCiFSln4CZb69CUTE/nmpVyZ5JLoM/tQWteDf8g 2HX3qPz13FATe9nmYZ1/iYByrCCtQudhj3iDdagQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Prateek Sood , "Steven Rostedt (VMware)" Subject: [PATCH 4.19 069/115] tracing: Fix lock inversion in trace_event_enable_tgid_record() Date: Tue, 7 Jan 2020 21:54:39 +0100 Message-Id: <20200107205303.812869492@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107205240.283674026@linuxfoundation.org> References: <20200107205240.283674026@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Prateek Sood commit 3a53acf1d9bea11b57c1f6205e3fe73f9d8a3688 upstream. Task T2 Task T3 trace_options_core_write() subsystem_open() mutex_lock(trace_types_lock) mutex_lock(event_mutex) set_tracer_flag() trace_event_enable_tgid_record() mutex_lock(trace_types_lock) mutex_lock(event_mutex) This gives a circular dependency deadlock between trace_types_lock and event_mutex. To fix this invert the usage of trace_types_lock and event_mutex in trace_options_core_write(). This keeps the sequence of lock usage consistent. Link: http://lkml.kernel.org/r/0101016eef175e38-8ca71caf-a4eb-480d-a1e6-6f0bbc015495-000000@us-west-2.amazonses.com Cc: stable@vger.kernel.org Fixes: d914ba37d7145 ("tracing: Add support for recording tgid of tasks") Signed-off-by: Prateek Sood Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 8 ++++++++ kernel/trace/trace_events.c | 8 ++++---- 2 files changed, 12 insertions(+), 4 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4370,6 +4370,10 @@ int trace_keep_overwrite(struct tracer * int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled) { + if ((mask == TRACE_ITER_RECORD_TGID) || + (mask == TRACE_ITER_RECORD_CMD)) + lockdep_assert_held(&event_mutex); + /* do nothing if flag is already set */ if (!!(tr->trace_flags & mask) == !!enabled) return 0; @@ -4435,6 +4439,7 @@ static int trace_set_options(struct trac cmp += 2; } + mutex_lock(&event_mutex); mutex_lock(&trace_types_lock); ret = match_string(trace_options, -1, cmp); @@ -4445,6 +4450,7 @@ static int trace_set_options(struct trac ret = set_tracer_flag(tr, 1 << ret, !neg); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); /* * If the first trailing whitespace is replaced with '\0' by strstrip, @@ -7457,9 +7463,11 @@ trace_options_core_write(struct file *fi if (val != 0 && val != 1) return -EINVAL; + mutex_lock(&event_mutex); mutex_lock(&trace_types_lock); ret = set_tracer_flag(tr, 1 << index, val); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); if (ret < 0) return ret; --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -327,7 +327,8 @@ void trace_event_enable_cmd_record(bool struct trace_event_file *file; struct trace_array *tr; - mutex_lock(&event_mutex); + lockdep_assert_held(&event_mutex); + do_for_each_event_file(tr, file) { if (!(file->flags & EVENT_FILE_FL_ENABLED)) @@ -341,7 +342,6 @@ void trace_event_enable_cmd_record(bool clear_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags); } } while_for_each_event_file(); - mutex_unlock(&event_mutex); } void trace_event_enable_tgid_record(bool enable) @@ -349,7 +349,8 @@ void trace_event_enable_tgid_record(bool struct trace_event_file *file; struct trace_array *tr; - mutex_lock(&event_mutex); + lockdep_assert_held(&event_mutex); + do_for_each_event_file(tr, file) { if (!(file->flags & EVENT_FILE_FL_ENABLED)) continue; @@ -363,7 +364,6 @@ void trace_event_enable_tgid_record(bool &file->flags); } } while_for_each_event_file(); - mutex_unlock(&event_mutex); } static int __ftrace_event_enable_disable(struct trace_event_file *file,