[PATCH v2 19/44] ftrace: only allocate the ret_stack 'fp' field when needed

[Josh Poimboeuf]

This saves some memory when HAVE_FUNCTION_GRAPH_FP_TEST isn't defined.
On x86_64 with newer versions of gcc which have -mfentry, it saves 400
bytes per task.

Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
 include/linux/ftrace.h               | 2 ++
 kernel/trace/trace_functions_graph.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 7d565af..4ad9ccc 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -795,7 +795,9 @@ struct ftrace_ret_stack {
        unsigned long func;
        unsigned long long calltime;
        unsigned long long subtime;
+#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
        unsigned long fp;
+#endif
 };
 
 /*
diff --git a/kernel/trace/trace_functions_graph.c 
b/kernel/trace/trace_functions_graph.c
index fc173cd..0e03ed0 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -171,7 +171,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long 
func, int *depth,
        current->ret_stack[index].func = func;
        current->ret_stack[index].calltime = calltime;
        current->ret_stack[index].subtime = 0;
+#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
        current->ret_stack[index].fp = frame_pointer;
+#endif
        *depth = current->curr_ret_stack;
 
        return 0;
-- 
2.7.4