---

yaml
---
r: 140821
b: refs/heads/master
c: 6ecc2d1
h: refs/heads/master
i:
  140819: 2ce07f7
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: eb594e45f6979cd10b18d87f7b3f02119e00a108
+refs/heads/master: 6ecc2d1ca39177edb6fbdb7412948b0e9f409d02

trunk/kernel/trace/events.c

@@ -2,6 +2,10 @@
  * This is the place to register all trace points as events.
  */
 
+/* someday this needs to go in a generic header */
+#define __STR(x) #x
+#define STR(x) __STR(x)
+
 #include <trace/trace_events.h>
 
 #include "trace_events.h"

trunk/kernel/trace/trace_events.c

@@ -345,11 +345,59 @@ static struct dentry *event_trace_events_dir(void)
 	return d_events;
 }
 
+struct event_subsystem {
+	struct list_head	list;
+	const char		*name;
+	struct dentry		*entry;
+};
+
+static LIST_HEAD(event_subsystems);
+
+static struct dentry *
+event_subsystem_dir(const char *name, struct dentry *d_events)
+{
+	struct event_subsystem *system;
+
+	/* First see if we did not already create this dir */
+	list_for_each_entry(system, &event_subsystems, list) {
+		if (strcmp(system->name, name) == 0)
+			return system->entry;
+	}
+
+	/* need to create new entry */
+	system = kmalloc(sizeof(*system), GFP_KERNEL);
+	if (!system) {
+		pr_warning("No memory to create event subsystem %s\n",
+			   name);
+		return d_events;
+	}
+
+	system->entry = debugfs_create_dir(name, d_events);
+	if (!system->entry) {
+		pr_warning("Could not create event subsystem %s\n",
+			   name);
+		kfree(system);
+		return d_events;
+	}
+
+	system->name = name;
+	list_add(&system->list, &event_subsystems);
+
+	return system->entry;
+}
+
 static int
 event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 {
 	struct dentry *entry;
 
+	/*
+	 * If the trace point header did not define TRACE_SYSTEM
+	 * then the system would be called "TRACE_SYSTEM".
+	 */
+	if (strcmp(call->system, "TRACE_SYSTEM") != 0)
+		d_events = event_subsystem_dir(call->system, d_events);
+
 	call->dir = debugfs_create_dir(call->name, d_events);
 	if (!call->dir) {
 		pr_warning("Could not create debugfs "

trunk/kernel/trace/trace_events.h

@@ -7,6 +7,7 @@
 
 struct ftrace_event_call {
 	char		*name;
+	char		*system;
 	struct dentry	*dir;
 	int		enabled;
 	int		(*regfunc)(void);
@@ -44,6 +45,7 @@ static struct ftrace_event_call __used					\
 __attribute__((__aligned__(4)))						\
 __attribute__((section("_ftrace_events"))) event_##call = {		\
 	.name 			= #call,				\
+	.system			= STR(TRACE_SYSTEM),			\
 	.regfunc		= ftrace_reg_event_##call,		\
 	.unregfunc		= ftrace_unreg_event_##call,		\
 }