Merge commit '0f17976568b3f72e676450af0c0db6f8752253d6' into trace/ftrace/core

Need to get the changes from 0f17976568 ("ftrace: Fix regression with
module command in stack_trace_filter") as it is required to fix some other
changes with stack_trace_filter and the new development code.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -6957,6 +6957,9 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash,
 	char *number;
 	int ret;
 
+	if (!tr)
+		return -ENODEV;
+
 	/* hash funcs only work with set_ftrace_filter */
 	if (!enable)
 		return -EINVAL;