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, 4 insertions, 5 deletions

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 374f3e42e29e..cc35606e9a3e 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -490,8 +490,7 @@ static int start_graph_tracing(void)
 	return ret;
 }
 
-int register_ftrace_graph(trace_func_graph_ret_t retfunc,
-			trace_func_graph_ent_t entryfunc)
+int register_ftrace_graph(struct fgraph_ops *gops)
 {
 	int ret = 0;
 
@@ -512,7 +511,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 		goto out;
 	}
 
-	ftrace_graph_return = retfunc;
+	ftrace_graph_return = gops->retfunc;
 
 	/*
 	 * Update the indirect function to the entryfunc, and the
@@ -520,7 +519,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 	 * call the update fgraph entry function to determine if
 	 * the entryfunc should be called directly or not.
 	 */
-	__ftrace_graph_entry = entryfunc;
+	__ftrace_graph_entry = gops->entryfunc;
 	ftrace_graph_entry = ftrace_graph_entry_test;
 	update_function_graph_func();
 
@@ -530,7 +529,7 @@ out:
 	return ret;
 }
 
-void unregister_ftrace_graph(void)
+void unregister_ftrace_graph(struct fgraph_ops *gops)
 {
 	mutex_lock(&ftrace_lock);