function_graph: Have profiler use new helper ftrace_graph_get_ret_stack()

The ret_stack processing is going to change, and that is going
to break anything that is accessing the ret_stack directly. One user is the
function graph profiler. By using the ftrace_graph_get_ret_stack() helper
function, the profiler can access the ret_stack entry without relying on the
implementation details of the stack itself.

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 11 insertions, 10 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d06fe588e650..8ef9fc226037 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -792,7 +792,7 @@ void ftrace_graph_graph_time_control(bool enable)
 
 static int profile_graph_entry(struct ftrace_graph_ent *trace)
 {
-        int index = current->curr_ret_stack;
+        struct ftrace_ret_stack *ret_stack;
 
         function_profile_call(trace->func, 0, NULL, NULL);
 
@@ -800,14 +800,16 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace)
         if (!current->ret_stack)
                 return 0;
 
-        if (index >= 0 && index < FTRACE_RETFUNC_DEPTH)
-                current->ret_stack[index].subtime = 0;
+        ret_stack = ftrace_graph_get_ret_stack(current, 0);
+        if (ret_stack)
+                ret_stack->subtime = 0;
 
         return 1;
 }
 
 static void profile_graph_return(struct ftrace_graph_ret *trace)
 {
+        struct ftrace_ret_stack *ret_stack;
         struct ftrace_profile_stat *stat;
         unsigned long long calltime;
         struct ftrace_profile *rec;
@@ -825,16 +827,15 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
         calltime = trace->rettime - trace->calltime;
 
         if (!fgraph_graph_time) {
-                int index;
-
-                index = current->curr_ret_stack;
 
                 /* Append this call time to the parent time to subtract */
-                if (index)
-                        current->ret_stack[index - 1].subtime += calltime;
+                ret_stack = ftrace_graph_get_ret_stack(current, 1);
+                if (ret_stack)
+                        ret_stack->subtime += calltime;
 
-                if (current->ret_stack[index].subtime < calltime)
-                        calltime -= current->ret_stack[index].subtime;
+                ret_stack = ftrace_graph_get_ret_stack(current, 0);
+                if (ret_stack && ret_stack->subtime < calltime)
+                        calltime -= ret_stack->subtime;
                 else
                         calltime = 0;
         }