From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751968AbdIUUWz (ORCPT ); Thu, 21 Sep 2017 16:22:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:46122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882AbdIUUWw (ORCPT ); Thu, 21 Sep 2017 16:22:52 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 537D021EAA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Thu, 21 Sep 2017 16:22:49 -0400 From: Steven Rostedt To: Tom Zanussi Cc: LKML , Ingo Molnar Subject: [PATCH] tracing: Reverse the order of trace_types_lock and event_mutex Message-ID: <20170921162249.0dde3dca@gandalf.local.home> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt (VMware) In order to make future changes where we need to call tracing_set_clock() from within an event command, the order of trace_types_lock and event_mutex must be reversed, as the event command will hold event_mutex and the trace_types_lock is taken from within tracing_set_clock(). Requested-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware) --- Index: linux-trace.git/kernel/trace/trace.c =================================================================== --- linux-trace.git.orig/kernel/trace/trace.c +++ linux-trace.git/kernel/trace/trace.c @@ -7687,6 +7687,7 @@ static int instance_mkdir(const char *na struct trace_array *tr; int ret; + mutex_lock(&event_mutex); mutex_lock(&trace_types_lock); ret = -EEXIST; @@ -7742,6 +7743,7 @@ static int instance_mkdir(const char *na list_add(&tr->list, &ftrace_trace_arrays); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return 0; @@ -7753,6 +7755,7 @@ static int instance_mkdir(const char *na out_unlock: mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return ret; @@ -7765,6 +7768,7 @@ static int instance_rmdir(const char *na int ret; int i; + mutex_lock(&event_mutex); mutex_lock(&trace_types_lock); ret = -ENODEV; @@ -7810,6 +7814,7 @@ static int instance_rmdir(const char *na out_unlock: mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return ret; } Index: linux-trace.git/kernel/trace/trace_events.c =================================================================== --- linux-trace.git.orig/kernel/trace/trace_events.c +++ linux-trace.git/kernel/trace/trace_events.c @@ -1406,8 +1406,8 @@ static int subsystem_open(struct inode * 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 * } } exit_loop: - mutex_unlock(&event_mutex); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); if (!system) return -ENODEV; @@ -2294,15 +2294,15 @@ static void __add_event_to_tracers(struc 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 { 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 no { 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 no trace_module_remove_events(mod); break; } - mutex_unlock(&event_mutex); mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return 0; } @@ -2950,24 +2950,24 @@ create_event_toplevel_files(struct dentr * creates the event hierachry in the @parent/events directory. * * Returns 0 on success. + * + * Must be called with event_mutex held. */ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr) { int ret; - mutex_lock(&event_mutex); + lockdep_assert_held(&event_mutex); ret = create_event_toplevel_files(parent, tr); if (ret) - goto out_unlock; + goto out; down_write(&trace_event_sem); __trace_add_event_dirs(tr); up_write(&trace_event_sem); - out_unlock: - mutex_unlock(&event_mutex); - + out: return ret; } @@ -2996,9 +2996,10 @@ early_event_add_tracer(struct dentry *pa return ret; } +/* Must be called with event_mutex held */ int event_trace_del_tracer(struct trace_array *tr) { - mutex_lock(&event_mutex); + lockdep_assert_held(&event_mutex); /* Disable any event triggers and associated soft-disabled events */ clear_event_triggers(tr); @@ -3019,8 +3020,6 @@ int event_trace_del_tracer(struct trace_ tr->event_dir = NULL; - mutex_unlock(&event_mutex); - return 0; }