| From: Tom Zanussi <tom.zanussi@linux.intel.com> |
| Date: Tue, 5 Sep 2017 16:57:47 -0500 |
| Subject: [PATCH 35/40] tracing: Reverse the order event_mutex/trace_types_lock |
| are taken |
| |
| 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 <tom.zanussi@linux.intel.com> |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| kernel/trace/trace_events.c | 16 ++++++++-------- |
| 1 file changed, 8 insertions(+), 8 deletions(-) |
| |
| --- a/kernel/trace/trace_events.c |
| +++ b/kernel/trace/trace_events.c |
| @@ -1366,8 +1366,8 @@ 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) { |
| @@ -1381,8 +1381,8 @@ 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; |
| @@ -2250,15 +2250,15 @@ 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; |
| } |
| |
| @@ -2312,13 +2312,13 @@ 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; |
| } |
| @@ -2385,8 +2385,8 @@ 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); |
| @@ -2395,8 +2395,8 @@ 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; |
| } |