trace: Move trace event enable from fs_initcall to core_initcall

This patch splits trace event initialization in two stages: * ftrace enable * sysfs event entry creation This allows to capture trace events from an earlier point by using 'trace_event' kernel parameter and is important to trace boot-up allocations. Note that, in order to enable events at core_initcall, it's necessary to move init_ftrace_syscalls() from core_initcall to early_initcall. Link: http://lkml.kernel.org/r/1347461277-25302-1-git-send-email-elezegarcia@gmail.com Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

trace: Move trace event enable from fs_initcall to core_initcall
This patch splits trace event initialization in two stages: * ftrace enable * sysfs event entry creation This allows to capture trace events from an earlier point by using 'trace_event' kernel parameter and is important to trace boot-up allocations. Note that, in order to enable events at core_initcall, it's necessary to move init_ftrace_syscalls() from core_initcall to early_initcall. Link: http://lkml.kernel.org/r/1347461277-25302-1-git-send-email-elezegarcia@gmail.com Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Ezequiel Garcia · Steven Rostedt
1 parent 5224c3a315
Showing 2 changed files with 73 additions and 37 deletions Side-by-side Diff
kernel/trace/trace_events.c
kernel/trace/trace_syscalls.c
@@ -1199,6 +1199,31 @@
 	return 0;
 }
  
+static void event_remove(struct ftrace_event_call *call)
+{
+	ftrace_event_enable_disable(call, 0);
+	if (call->event.funcs)
+		__unregister_ftrace_event(&call->event);
+	list_del(&call->list);
+}
+
+static int event_init(struct ftrace_event_call *call)
+{
+	int ret = 0;
+
+	if (WARN_ON(!call->name))
+		return -EINVAL;
+
+	if (call->class->raw_init) {
+		ret = call->class->raw_init(call);
+		if (ret < 0 && ret != -ENOSYS)
+			pr_warn("Could not initialize trace events/%s\n",
+				call->name);
+	}
+
+	return ret;
+}
+
 static int
 __trace_add_event_call(struct ftrace_event_call *call, struct module *mod,
 		       const struct file_operations *id,
  
@@ -1209,20 +1234,10 @@
 	struct dentry *d_events;
 	int ret;
  
-	/* The linker may leave blanks */
-	if (!call->name)
-		return -EINVAL;
+	ret = event_init(call);
+	if (ret < 0)
+		return ret;
  
-	if (call->class->raw_init) {
-		ret = call->class->raw_init(call);
-		if (ret < 0) {
-			if (ret != -ENOSYS)
-				pr_warning("Could not initialize trace events/%s\n",
-					   call->name);
-			return ret;
-		}
-	}
-
 	d_events = event_trace_events_dir();
 	if (!d_events)
 		return -ENOENT;
  
@@ -1272,13 +1287,10 @@
  */
 static void __trace_remove_event_call(struct ftrace_event_call *call)
 {
-	ftrace_event_enable_disable(call, 0);
-	if (call->event.funcs)
-		__unregister_ftrace_event(&call->event);
-	debugfs_remove_recursive(call->dir);
-	list_del(&call->list);
+	event_remove(call);
 	trace_destroy_fields(call);
 	destroy_preds(call);
+	debugfs_remove_recursive(call->dir);
 	remove_subsystem_dir(call->class->system);
 }
  
  
  
@@ -1450,15 +1462,43 @@
 }
 __setup("trace_event=", setup_trace_event);
  
+static __init int event_trace_enable(void)
+{
+	struct ftrace_event_call **iter, *call;
+	char *buf = bootup_event_buf;
+	char *token;
+	int ret;
+
+	for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {
+
+		call = *iter;
+		ret = event_init(call);
+		if (!ret)
+			list_add(&call->list, &ftrace_events);
+	}
+
+	while (true) {
+		token = strsep(&buf, ",");
+
+		if (!token)
+			break;
+		if (!*token)
+			continue;
+
+		ret = ftrace_set_clr_event(token, 1);
+		if (ret)
+			pr_warn("Failed to enable trace event: %s\n", token);
+	}
+	return 0;
+}
+
 static __init int event_trace_init(void)
 {
-	struct ftrace_event_call **call;
+	struct ftrace_event_call *call;
 	struct dentry *d_tracer;
 	struct dentry *entry;
 	struct dentry *d_events;
 	int ret;
-	char *buf = bootup_event_buf;
-	char *token;
  
 	d_tracer = tracing_init_dentry();
 	if (!d_tracer)
  
  
  
@@ -1497,32 +1537,28 @@
 	if (trace_define_common_fields())
 		pr_warning("tracing: Failed to allocate common fields");
  
-	for_each_event(call, __start_ftrace_events, __stop_ftrace_events) {
-		__trace_add_event_call(*call, NULL, &ftrace_event_id_fops,
+	/*
+	 * Early initialization already enabled ftrace event.
+	 * Now it's only necessary to create the event directory.
+	 */
+	list_for_each_entry(call, &ftrace_events, list) {
+
+		ret = event_create_dir(call, d_events,
+				       &ftrace_event_id_fops,
 				       &ftrace_enable_fops,
 				       &ftrace_event_filter_fops,
 				       &ftrace_event_format_fops);
+		if (ret < 0)
+			event_remove(call);
 	}
  
-	while (true) {
-		token = strsep(&buf, ",");
-
-		if (!token)
-			break;
-		if (!*token)
-			continue;
-
-		ret = ftrace_set_clr_event(token, 1);
-		if (ret)
-			pr_warning("Failed to enable trace event: %s\n", token);
-	}
-
 	ret = register_module_notifier(&trace_module_nb);
 	if (ret)
 		pr_warning("Failed to register trace events module notifier\n");
  
 	return 0;
 }
+core_initcall(event_trace_enable);
 fs_initcall(event_trace_init);
  
 #ifdef CONFIG_FTRACE_STARTUP_TEST
@@ -487,7 +487,7 @@
  
 	return 0;
 }
-core_initcall(init_ftrace_syscalls);
+early_initcall(init_ftrace_syscalls);
  
 #ifdef CONFIG_PERF_EVENTS
...	...	@@ -1199,6 +1199,31 @@
1199	1199	return 0;
1200	1200	}
1201	1201
	1202	+static void event_remove(struct ftrace_event_call *call)
	1203	+{
	1204	+ ftrace_event_enable_disable(call, 0);
	1205	+ if (call->event.funcs)
	1206	+ __unregister_ftrace_event(&call->event);
	1207	+ list_del(&call->list);
	1208	+}
	1209	+
	1210	+static int event_init(struct ftrace_event_call *call)
	1211	+{
	1212	+ int ret = 0;
	1213	+
	1214	+ if (WARN_ON(!call->name))
	1215	+ return -EINVAL;
	1216	+
	1217	+ if (call->class->raw_init) {
	1218	+ ret = call->class->raw_init(call);
	1219	+ if (ret < 0 && ret != -ENOSYS)
	1220	+ pr_warn("Could not initialize trace events/%s\n",
	1221	+ call->name);
	1222	+ }
	1223	+
	1224	+ return ret;
	1225	+}
	1226	+
1202	1227	static int
1203	1228	__trace_add_event_call(struct ftrace_event_call call, struct module mod,
1204	1229	const struct file_operations *id,
1205	1230
...	...	@@ -1209,20 +1234,10 @@
1209	1234	struct dentry *d_events;
1210	1235	int ret;
1211	1236
1212		- /* The linker may leave blanks */
1213		- if (!call->name)
1214		- return -EINVAL;
	1237	+ ret = event_init(call);
	1238	+ if (ret < 0)
	1239	+ return ret;
1215	1240
1216		- if (call->class->raw_init) {
1217		- ret = call->class->raw_init(call);
1218		- if (ret < 0) {
1219		- if (ret != -ENOSYS)
1220		- pr_warning("Could not initialize trace events/%s\n",
1221		- call->name);
1222		- return ret;
1223		- }
1224		- }
1225		-
1226	1241	d_events = event_trace_events_dir();
1227	1242	if (!d_events)
1228	1243	return -ENOENT;
1229	1244
...	...	@@ -1272,13 +1287,10 @@
1272	1287	*/
1273	1288	static void __trace_remove_event_call(struct ftrace_event_call *call)
1274	1289	{
1275		- ftrace_event_enable_disable(call, 0);
1276		- if (call->event.funcs)
1277		- __unregister_ftrace_event(&call->event);
1278		- debugfs_remove_recursive(call->dir);
1279		- list_del(&call->list);
	1290	+ event_remove(call);
1280	1291	trace_destroy_fields(call);
1281	1292	destroy_preds(call);
	1293	+ debugfs_remove_recursive(call->dir);
1282	1294	remove_subsystem_dir(call->class->system);
1283	1295	}
1284	1296
1285	1297
1286	1298
...	...	@@ -1450,15 +1462,43 @@
1450	1462	}
1451	1463	__setup("trace_event=", setup_trace_event);
1452	1464
	1465	+static __init int event_trace_enable(void)
	1466	+{
	1467	+ struct ftrace_event_call *iter, call;
	1468	+ char *buf = bootup_event_buf;
	1469	+ char *token;
	1470	+ int ret;
	1471	+
	1472	+ for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {
	1473	+
	1474	+ call = *iter;
	1475	+ ret = event_init(call);
	1476	+ if (!ret)
	1477	+ list_add(&call->list, &ftrace_events);
	1478	+ }
	1479	+
	1480	+ while (true) {
	1481	+ token = strsep(&buf, ",");
	1482	+
	1483	+ if (!token)
	1484	+ break;
	1485	+ if (!*token)
	1486	+ continue;
	1487	+
	1488	+ ret = ftrace_set_clr_event(token, 1);
	1489	+ if (ret)
	1490	+ pr_warn("Failed to enable trace event: %s\n", token);
	1491	+ }
	1492	+ return 0;
	1493	+}
	1494	+
1453	1495	static __init int event_trace_init(void)
1454	1496	{
1455		- struct ftrace_event_call **call;
	1497	+ struct ftrace_event_call *call;
1456	1498	struct dentry *d_tracer;
1457	1499	struct dentry *entry;
1458	1500	struct dentry *d_events;
1459	1501	int ret;
1460		- char *buf = bootup_event_buf;
1461		- char *token;
1462	1502
1463	1503	d_tracer = tracing_init_dentry();
1464	1504	if (!d_tracer)
1465	1505
1466	1506
1467	1507
...	...	@@ -1497,32 +1537,28 @@
1497	1537	if (trace_define_common_fields())
1498	1538	pr_warning("tracing: Failed to allocate common fields");
1499	1539
1500		- for_each_event(call, __start_ftrace_events, __stop_ftrace_events) {
1501		- __trace_add_event_call(*call, NULL, &ftrace_event_id_fops,
	1540	+ /*
	1541	+ * Early initialization already enabled ftrace event.
	1542	+ * Now it's only necessary to create the event directory.
	1543	+ */
	1544	+ list_for_each_entry(call, &ftrace_events, list) {
	1545	+
	1546	+ ret = event_create_dir(call, d_events,
	1547	+ &ftrace_event_id_fops,
1502	1548	&ftrace_enable_fops,
1503	1549	&ftrace_event_filter_fops,
1504	1550	&ftrace_event_format_fops);
	1551	+ if (ret < 0)
	1552	+ event_remove(call);
1505	1553	}
1506	1554
1507		- while (true) {
1508		- token = strsep(&buf, ",");
1509		-
1510		- if (!token)
1511		- break;
1512		- if (!*token)
1513		- continue;
1514		-
1515		- ret = ftrace_set_clr_event(token, 1);
1516		- if (ret)
1517		- pr_warning("Failed to enable trace event: %s\n", token);
1518		- }
1519		-
1520	1555	ret = register_module_notifier(&trace_module_nb);
1521	1556	if (ret)
1522	1557	pr_warning("Failed to register trace events module notifier\n");
1523	1558
1524	1559	return 0;
1525	1560	}
	1561	+core_initcall(event_trace_enable);
1526	1562	fs_initcall(event_trace_init);
1527	1563
1528	1564	#ifdef CONFIG_FTRACE_STARTUP_TEST
...	...	@@ -487,7 +487,7 @@
487	487
488	488	return 0;
489	489	}
490		-core_initcall(init_ftrace_syscalls);
	490	+early_initcall(init_ftrace_syscalls);
491	491
492	492	#ifdef CONFIG_PERF_EVENTS
493	493