tracing: Add ftrace_event_call void * 'data' field

add an optional void * pointer to 'ftrace_event_call' that is
passed in for regfunc and unregfunc.

This prepares for syscall tracepoints creation by passing the name of
the syscall we want to trace and then retrieve its number through our
arch syscall table.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

include/linux/ftrace_event.h

@@ -112,8 +112,8 @@ struct ftrace_event_call {
 	struct dentry		*dir;
 	struct trace_event	*event;
 	int			enabled;
-	int			(*regfunc)(void);
-	void			(*unregfunc)(void);
+	int			(*regfunc)(void *);
+	void			(*unregfunc)(void *);
 	int			id;
 	int			(*raw_init)(void);
 	int			(*show_format)(struct trace_seq *s);
@@ -122,6 +122,7 @@ struct ftrace_event_call {
 	int			filter_active;
 	struct event_filter	*filter;
 	void			*mod;
+	void			*data;
 
 	atomic_t		profile_count;
 	int			(*profile_enable)(struct ftrace_event_call *);

include/trace/ftrace.h

@@ -568,7 +568,7 @@ static void ftrace_raw_event_##call(proto)				\
 		trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
 }									\
 									\
-static int ftrace_raw_reg_event_##call(void)				\
+static int ftrace_raw_reg_event_##call(void *ptr)			\
 {									\
 	int ret;							\
 									\
@@ -579,7 +579,7 @@ static int ftrace_raw_reg_event_##call(void)				\
 	return ret;							\
 }									\
 									\
-static void ftrace_raw_unreg_event_##call(void)				\
+static void ftrace_raw_unreg_event_##call(void *ptr)			\
 {									\
 	unregister_trace_##call(ftrace_raw_event_##call);		\
 }									\

kernel/trace/trace_events.c

@@ -86,14 +86,14 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
 		if (call->enabled) {
 			call->enabled = 0;
 			tracing_stop_cmdline_record();
-			call->unregfunc();
+			call->unregfunc(call->data);
 		}
 		break;
 	case 1:
 		if (!call->enabled) {
 			call->enabled = 1;
 			tracing_start_cmdline_record();
-			call->regfunc();
+			call->regfunc(call->data);
 		}
 		break;
 	}