fgraph: Add new fgraph_ops structure to enable function graph hooks

Currently the registering of function graph is to pass in a entry and return
function. We need to have a way to associate those functions together where
the entry can determine to run the return hook. Having a structure that
contains both functions will facilitate the process of converting the code
to be able to do such.

This is similar to the way function hooks are enabled (it passes in
ftrace_ops). Instead of passing in the functions to use, a single structure
is passed in to the registering function.

The unregister function is now passed in the fgraph_ops handle. When we
allow more than one callback to the function graph hooks, this will let the
system know which one to remove.

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

1 files changed, 7 insertions, 11 deletions

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 98ea6d28df15..d3294721f119 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -218,6 +218,11 @@ static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
 	atomic_dec(&data->disabled);
 }
 
+static struct fgraph_ops fgraph_ops = {
+	.entryfunc		= &irqsoff_graph_entry,
+	.retfunc		= &irqsoff_graph_return,
+};
+
 static void irqsoff_trace_open(struct trace_iterator *iter)
 {
 	if (is_graph(iter->tr))
@@ -272,13 +277,6 @@ __trace_function(struct trace_array *tr,
 #else
 #define __trace_function trace_function
 
-#ifdef CONFIG_FUNCTION_TRACER
-static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
-{
-	return -1;
-}
-#endif
-
 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
 {
 	return TRACE_TYPE_UNHANDLED;
@@ -288,7 +286,6 @@ static void irqsoff_trace_open(struct trace_iterator *iter) { }
 static void irqsoff_trace_close(struct trace_iterator *iter) { }
 
 #ifdef CONFIG_FUNCTION_TRACER
-static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
 static void irqsoff_print_header(struct seq_file *s)
 {
 	trace_default_header(s);
@@ -468,8 +465,7 @@ static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
 		return 0;
 
 	if (graph)
-		ret = register_ftrace_graph(&irqsoff_graph_return,
-					    &irqsoff_graph_entry);
+		ret = register_ftrace_graph(&fgraph_ops);
 	else
 		ret = register_ftrace_function(tr->ops);
 
@@ -485,7 +481,7 @@ static void unregister_irqsoff_function(struct trace_array *tr, int graph)
 		return;
 
 	if (graph)
-		unregister_ftrace_graph();
+		unregister_ftrace_graph(&fgraph_ops);
 	else
 		unregister_ftrace_function(tr->ops);