tracing/ftrace: provide the macro task_curr_ret_stack()

Impact: cleanup

As suggested by Steven Rostedt, this patch provide a new macro
task_curr_ret_stack() to move the cpp conditionnal CONFIG into
the linux/ftrace.h headers.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index b295d31..b9b4d0a 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -8,6 +8,7 @@
 #include <linux/types.h>
 #include <linux/kallsyms.h>
 #include <linux/bitops.h>
+#include <linux/sched.h>
 
 #ifdef CONFIG_FUNCTION_TRACER
 
@@ -387,9 +388,19 @@
 
 extern void ftrace_graph_init_task(struct task_struct *t);
 extern void ftrace_graph_exit_task(struct task_struct *t);
+
+static inline int task_curr_ret_stack(struct task_struct *t)
+{
+	return t->curr_ret_stack;
+}
 #else
 static inline void ftrace_graph_init_task(struct task_struct *t) { }
 static inline void ftrace_graph_exit_task(struct task_struct *t) { }
+
+static inline int task_curr_ret_stack(struct task_struct *tsk)
+{
+	return -1;
+}
 #endif
 
 #ifdef CONFIG_TRACING