tracing: Move a printk out of ftrace_raw_reg_event_foo()

Move the printk from each ftrace_raw_reg_event_foo() to
its caller ftrace_event_enable_disable(). This avoids each
regfunc trace event callbacks to handle a same error report
that can be carried from the caller.

See how much space this saves:

   text    data     bss     dec     hex filename
5345151 1961864 7103260 14410275         dbe223 vmlinux.o.old
5331487 1961864 7103260 14396611         dbacc3 vmlinux.o

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <4B1DC4AC.802@cn.fujitsu.com>
[start cmdline record before calling regfunc to avoid lost
window of pid to comm resolution]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

include/trace/ftrace.h

@@ -555,13 +555,7 @@ static void ftrace_profile_disable_##name(struct ftrace_event_call *unused)\
  *
  * static int ftrace_reg_event_<call>(struct ftrace_event_call *unused)
  * {
- *	int ret;
+ *	return register_trace_<call>(ftrace_event_<call>);
- *
- *	ret = register_trace_<call>(ftrace_event_<call>);
- *	if (!ret)
- *		pr_info("event trace: Could not activate trace point "
- *			"probe to  <call>");
- *	return ret;
  * }
  *
  * static void ftrace_unreg_event_<call>(struct ftrace_event_call *unused)
@@ -710,13 +704,7 @@ static void ftrace_raw_event_##call(proto)				\
 									\
 static int ftrace_raw_reg_event_##call(struct ftrace_event_call *unused)\
 {									\
-	int ret;							\
+	return register_trace_##call(ftrace_raw_event_##call);		\
-									\
-	ret = register_trace_##call(ftrace_raw_event_##call);		\
-	if (ret)							\
-		pr_info("event trace: Could not activate trace point "	\
-			"probe to %s\n", #call);			\
-	return ret;							\
 }									\
 									\
 static void ftrace_raw_unreg_event_##call(struct ftrace_event_call *unused)\

kernel/trace/trace_events.c

@@ -118,9 +118,11 @@ int trace_event_raw_init(struct ftrace_event_call *call)
 }
 EXPORT_SYMBOL_GPL(trace_event_raw_init);
 
-static void ftrace_event_enable_disable(struct ftrace_event_call *call,
+static int ftrace_event_enable_disable(struct ftrace_event_call *call,
 					int enable)
 {
+	int ret = 0;
+
 	switch (enable) {
 	case 0:
 		if (call->enabled) {
@@ -131,12 +133,20 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
 		break;
 	case 1:
 		if (!call->enabled) {
-			call->enabled = 1;
 			tracing_start_cmdline_record();
-			call->regfunc(call);
+			ret = call->regfunc(call);
+			if (ret) {
+				tracing_stop_cmdline_record();
+				pr_info("event trace: Could not enable event "
+					"%s\n", call->name);
+				break;
+			}
+			call->enabled = 1;
 		}
 		break;
 	}
+
+	return ret;
 }
 
 static void ftrace_clear_events(void)
@@ -415,7 +425,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 	case 0:
 	case 1:
 		mutex_lock(&event_mutex);
-		ftrace_event_enable_disable(call, val);
+		ret = ftrace_event_enable_disable(call, val);
 		mutex_unlock(&event_mutex);
 		break;
 
@@ -425,7 +435,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 
 	*ppos += cnt;
 
-	return cnt;
+	return ret ? ret : cnt;
 }
 
 static ssize_t

kernel/trace/trace_syscalls.c

@@ -325,10 +325,7 @@ int reg_event_syscall_enter(struct ftrace_event_call *call)
 	mutex_lock(&syscall_trace_lock);
 	if (!sys_refcount_enter)
 		ret = register_trace_sys_enter(ftrace_syscall_enter);
-	if (ret) {
+	if (!ret) {
-		pr_info("event trace: Could not activate"
-				"syscall entry trace point");
-	} else {
 		set_bit(num, enabled_enter_syscalls);
 		sys_refcount_enter++;
 	}
@@ -362,10 +359,7 @@ int reg_event_syscall_exit(struct ftrace_event_call *call)
 	mutex_lock(&syscall_trace_lock);
 	if (!sys_refcount_exit)
 		ret = register_trace_sys_exit(ftrace_syscall_exit);
-	if (ret) {
+	if (!ret) {
-		pr_info("event trace: Could not activate"
-				"syscall exit trace point");
-	} else {
 		set_bit(num, enabled_exit_syscalls);
 		sys_refcount_exit++;
 	}