tracing/user_events: Hold event_mutex during dyn_event_add

Make sure the event_mutex is properly held during dyn_event_add call.
This is required when adding dynamic events.

Link: https://lkml.kernel.org/r/20220328223225.1992-1-beaub@linux.microsoft.com
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 8b3d241..61d78d6 100644 (file)
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -1165,11 +1165,11 @@ static int user_event_parse(char *name, char *args, char *flags,
 #endif
 
        mutex_lock(&event_mutex);
+
        ret = user_event_trace_register(user);
-       mutex_unlock(&event_mutex);
 
        if (ret)
-               goto put_user;
+               goto put_user_lock;
 
        user->index = index;
 
@@ -1181,8 +1181,12 @@ static int user_event_parse(char *name, char *args, char *flags,
        set_bit(user->index, page_bitmap);
        hash_add(register_table, &user->node, key);
 
+       mutex_unlock(&event_mutex);
+
        *newuser = user;
        return 0;
+put_user_lock:
+       mutex_unlock(&event_mutex);
 put_user:
        user_event_destroy_fields(user);
        user_event_destroy_validators(user);