tracing, function_graph: Add context-info support for function_graph tracer

The function_graph tracer does not follow global context-info option.
Adding TRACE_ITER_CONTEXT_INFO trace_flags check to enable it.

With following commands:
	# echo function_graph > ./current_tracer
	# echo 0 > options/context-info
	# cat trace

This is what it looked like before:
# tracer: function_graph
#
#     TIME        CPU  DURATION                  FUNCTION CALLS
#      |          |     |   |                     |   |   |   |
 1)   0.079 us    |          } /* __vma_link_rb */
 1)   0.056 us    |          copy_page_range();
 1)               |          security_vm_enough_memory() {
...

This is what it looks like now:
# tracer: function_graph
#
  } /* update_ts_time_stats */
  timekeeping_max_deferment();
...
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1307113131-10045-6-git-send-email-jolsa@redhat.comSigned-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_functions_graph.c

@@ -613,6 +613,7 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 		addr >= (unsigned long)__irqentry_text_end)
 		return TRACE_TYPE_UNHANDLED;
 
+	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
 		/* Absolute time */
 		if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
 			ret = print_graph_abs_time(iter->ts, s);
@@ -636,6 +637,7 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 			if (!ret)
 				return TRACE_TYPE_PARTIAL_LINE;
 		}
+	}
 
 	/* No overhead */
 	ret = print_graph_duration(DURATION_FILL_START, s, flags);
@@ -710,7 +712,8 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s,
 {
 	int ret = -1;
 
-	if (!(flags & TRACE_GRAPH_PRINT_DURATION))
+	if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
+	    !(trace_flags & TRACE_ITER_CONTEXT_INFO))
 			return TRACE_TYPE_HANDLED;
 
 	/* No real adata, just filling the column with spaces */
@@ -879,6 +882,9 @@ print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 			return TRACE_TYPE_PARTIAL_LINE;
 	}
 
+	if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
+		return 0;
+
 	/* Absolute time */
 	if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
 		ret = print_graph_abs_time(iter->ts, s);
@@ -1346,6 +1352,9 @@ void print_graph_headers_flags(struct seq_file *s, u32 flags)
 {
 	struct trace_iterator *iter = s->private;
 
+	if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
+		return;
+
 	if (trace_flags & TRACE_ITER_LATENCY_FMT) {
 		/* print nothing if the buffers are empty */
 		if (trace_empty(iter))