function_graph: Do not expose the graph_time option when profiler is not configured

When the function profiler is not configured, the "graph_time" option is
meaningless, as the function profiler is the only thing that makes use of
it. Do not expose it if the profiler is not configured.

Link: http://lkml.kernel.org/r/20181123061133.GA195223@google.comReported-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace.h

@@ -862,7 +862,12 @@ static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash)
 #define TRACE_GRAPH_PRINT_FILL_MASK	(0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT)
 
 extern void ftrace_graph_sleep_time_control(bool enable);
+
+#ifdef CONFIG_FUNCTION_PROFILER
 extern void ftrace_graph_graph_time_control(bool enable);
+#else
+static inline void ftrace_graph_graph_time_control(bool enable) { }
+#endif
 
 extern enum print_line_t
 print_graph_function_flags(struct trace_iterator *iter, u32 flags);

kernel/trace/trace_functions_graph.c

@@ -60,8 +60,12 @@ static struct tracer_opt trace_opts[] = {
 	{ TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
 	/* Include sleep time (scheduled out) between entry and return */
 	{ TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
+
+#ifdef CONFIG_FUNCTION_PROFILER
 	/* Include time within nested functions */
 	{ TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
+#endif
+
 	{ } /* Empty entry */
 };