From: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> commit 12ecef0cb12102d8c034770173d2d1363cb97d52 upstream. 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(). Link: http://lkml.kernel.org/r/20170921162249.0dde3dca@xxxxxxxxxxxxxxxxxx Requested-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Andress Kuo (郭孟修) <Andress.Kuo@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace.c | 5 +++++ kernel/trace/trace_events.c | 31 +++++++++++++++---------------- 2 files changed, 20 insertions(+), 16 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7720,6 +7720,7 @@ static int instance_mkdir(const char *na struct trace_array *tr; int ret; + mutex_lock(&event_mutex); mutex_lock(&trace_types_lock); ret = -EEXIST; @@ -7775,6 +7776,7 @@ 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; @@ -7786,6 +7788,7 @@ static int instance_mkdir(const char *na out_unlock: mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return ret; @@ -7798,6 +7801,7 @@ static int instance_rmdir(const char *na int ret; int i; + mutex_lock(&event_mutex); mutex_lock(&trace_types_lock); ret = -ENODEV; @@ -7843,6 +7847,7 @@ static int instance_rmdir(const char *na out_unlock: mutex_unlock(&trace_types_lock); + mutex_unlock(&event_mutex); return ret; } --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1403,8 +1403,8 @@ 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) { @@ -1418,8 +1418,8 @@ 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; @@ -2305,15 +2305,15 @@ 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; } @@ -2367,13 +2367,13 @@ 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; } @@ -2435,8 +2435,8 @@ 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); @@ -2445,8 +2445,8 @@ 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; } @@ -2961,24 +2961,24 @@ 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; } @@ -3007,9 +3007,10 @@ 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); @@ -3030,8 +3031,6 @@ int event_trace_del_tracer(struct trace_ tr->event_dir = NULL; - mutex_unlock(&event_mutex); - return 0; }
