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Subject[PATCH] ftrace: Access ret_stack->subtime only in the function profiler
Date
The subtime is used only for function profiler with function graph
tracer enabled. Move the definition of subtime under
CONFIG_FUNCTION_PROFILER to reduce the memory usage. Also move the
initialization of subtime into the graph entry callback.

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
include/linux/ftrace.h | 2 ++
kernel/trace/ftrace.c | 6 ++++++
kernel/trace/trace_functions_graph.c | 1 -
3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6f93ac46e7f0..b3d34d3e0e7e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -794,7 +794,9 @@ struct ftrace_ret_stack {
unsigned long ret;
unsigned long func;
unsigned long long calltime;
+#ifdef CONFIG_FUNCTION_PROFILER
unsigned long long subtime;
+#endif
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
unsigned long fp;
#endif
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 84752c8e28b5..2050a7652a86 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -872,7 +872,13 @@ function_profile_call(unsigned long ip, unsigned long parent_ip,
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int profile_graph_entry(struct ftrace_graph_ent *trace)
{
+ int index = trace->depth;
+
function_profile_call(trace->func, 0, NULL, NULL);
+
+ if (index >= 0 && index < FTRACE_RETFUNC_DEPTH)
+ current->ret_stack[index].subtime = 0;
+
return 1;
}

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 0cbe38a844fa..9c7ffa4df5a8 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -170,7 +170,6 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
current->ret_stack[index].ret = ret;
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
--
2.9.3
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