ftrace: Add :mod: caching infrastructure to trace_array

This is the start of the infrastructure work to allow for tracing module
functions before it is loaded.

Currently the following command:

  # echo :mod:some-mod > set_ftrace_filter

will enable tracing of all functions within the module "some-mod" if it is
loaded. What we want, is if the module is not loaded, that line will be
saved. When the module is loaded, then the "some-mod" will have that line
executed on it, so that the functions within it starts being traced.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 69a3ab3ee4f5..d63550cdbdfa 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -263,7 +263,10 @@ struct trace_array {
 	struct ftrace_ops	*ops;
 	struct trace_pid_list	__rcu *function_pids;
 #ifdef CONFIG_DYNAMIC_FTRACE
+	/* All of these are protected by the ftrace_lock */
 	struct list_head	func_probes;
+	struct list_head	mod_trace;
+	struct list_head	mod_notrace;
 #endif
 	/* function tracing enabled */
 	int			function_enabled;
@@ -761,6 +764,15 @@ enum print_line_t print_trace_line(struct trace_iterator *iter);
 
 extern char trace_find_mark(unsigned long long duration);
 
+struct ftrace_hash;
+
+struct ftrace_mod_load {
+	struct list_head	list;
+	char			*func;
+	char			*module;
+	int			 enable;
+};
+
 struct ftrace_hash {
 	unsigned long		size_bits;
 	struct hlist_head	*buckets;