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>

3 files changed, 19 insertions, 27 deletions

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 2af2f7a2c1bd..0c21af85211c 100644
--- a/include/trace/ftrace.h
+++ b/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;
- *
- *      ret = register_trace_<call>(ftrace_event_<call>);
- *      if (!ret)
- *              pr_info("event trace: Could not activate trace point "
- *                      "probe to  <call>");
- *      return ret;
+ *      return register_trace_<call>(ftrace_event_<call>);
  * }
  *
  * 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;                                                        \
-                                                                        \
-        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;                                                     \
+        return register_trace_##call(ftrace_raw_event_##call);          \
 }                                                                       \
                                                                         \
 static void ftrace_raw_unreg_event_##call(struct ftrace_event_call *unused)\
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 97b0b3aa166d..189b09baf4fb 100644
--- a/kernel/trace/trace_events.c
+++ b/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
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index b957edd0ca3b..75289f372dd2 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/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) {
-                pr_info("event trace: Could not activate"
-                                "syscall entry trace point");
-        } else {
+        if (!ret) {
                 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) {
-                pr_info("event trace: Could not activate"
-                                "syscall exit trace point");
-        } else {
+        if (!ret) {
                 set_bit(num, enabled_exit_syscalls);
                 sys_refcount_exit++;
         }