From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754193AbdIEV7v (ORCPT ); Tue, 5 Sep 2017 17:59:51 -0400 Received: from mga04.intel.com ([192.55.52.120]:34537 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754157AbdIEV7k (ORCPT ); Tue, 5 Sep 2017 17:59:40 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,481,1498546800"; d="scan'208";a="125866449" From: Tom Zanussi To: rostedt@goodmis.org Cc: tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org, vedang.patel@intel.com, bigeasy@linutronix.de, joel.opensrc@gmail.com, joelaf@google.com, mathieu.desnoyers@efficios.com, baohong.liu@intel.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Tom Zanussi Subject: [PATCH v2 35/40] tracing: Reverse the order event_mutex/trace_types_lock are taken Date: Tue, 5 Sep 2017 16:57:47 -0500 Message-Id: <4b52f9b1c49599780af1a193736df609b2785a63.1504642143.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change the order event_mutex and trace_types_lock are taken, to avoid circular dependencies and lockdep spew. Changing the order shouldn't matter to any current code, but does to anything that takes the event_mutex first and then trace_types_lock. This is the case when calling tracing_set_clock from inside an event command, which already holds the event_mutex. Signed-off-by: Tom Zanussi --- kernel/trace/trace_events.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index c93540c..889802c 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1406,8 +1406,8 @@ static int subsystem_open(struct inode *inode, struct file *filp) return -ENODEV; /* Make sure the system still exists */ - mutex_lock(&trace_types_lock); mutex_lock(&event_mutex); + mutex_lock(&trace_types_lock); list_for_each_entry(tr, &ftrace_trace_arrays, list) { list_for_each_entry(dir, &tr->systems, list) { if (dir == inode->i_private) { @@ -1421,8 +1421,8 @@ static int subsystem_open(struct inode *inode, struct file *filp) } } exit_loop: - mutex_unlock(&event_mutex); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); if (!system) return -ENODEV; @@ -2294,15 +2294,15 @@ void trace_event_eval_update(struct trace_eval_map **map, int len) int trace_add_event_call(struct trace_event_call *call) { int ret; - mutex_lock(&trace_types_lock); mutex_lock(&event_mutex); + mutex_lock(&trace_types_lock); ret = __register_event(call, NULL); if (ret >= 0) __add_event_to_tracers(call); - mutex_unlock(&event_mutex); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return ret; } @@ -2356,13 +2356,13 @@ int trace_remove_event_call(struct trace_event_call *call) { int ret; - mutex_lock(&trace_types_lock); mutex_lock(&event_mutex); + mutex_lock(&trace_types_lock); down_write(&trace_event_sem); ret = probe_remove_event_call(call); up_write(&trace_event_sem); - mutex_unlock(&event_mutex); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return ret; } @@ -2424,8 +2424,8 @@ static int trace_module_notify(struct notifier_block *self, { struct module *mod = data; - mutex_lock(&trace_types_lock); mutex_lock(&event_mutex); + mutex_lock(&trace_types_lock); switch (val) { case MODULE_STATE_COMING: trace_module_add_events(mod); @@ -2434,8 +2434,8 @@ static int trace_module_notify(struct notifier_block *self, trace_module_remove_events(mod); break; } - mutex_unlock(&event_mutex); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return 0; } -- 1.9.3