tracing: Use class->reg() for all registering of events

Because kprobes and syscalls need special processing to register
events, the class->reg() method was created to handle the differences.

But instead of creating a default ->reg for perf and ftrace events,
the code was scattered with:

	if (class->reg)
		class->reg();
	else
		default_reg();

This is messy and can also lead to bugs.

This patch cleans up this code and creates a default reg() entry for
the events allowing for the code to directly call the class->reg()
without the condition.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 39 insertions, 35 deletions

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 6053982dc302..23751659582e 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -54,13 +54,7 @@ static int perf_trace_event_init(struct ftrace_event_call *tp_event,
                 }
         }
 
-        if (tp_event->class->reg)
-                ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER);
-        else
-                ret = tracepoint_probe_register(tp_event->name,
-                                                tp_event->class->perf_probe,
-                                                tp_event);
-
+        ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER);
         if (ret)
                 goto fail;
 
@@ -94,9 +88,7 @@ int perf_trace_init(struct perf_event *p_event)
         mutex_lock(&event_mutex);
         list_for_each_entry(tp_event, &ftrace_events, list) {
                 if (tp_event->event.type == event_id &&
-                    tp_event->class &&
-                    (tp_event->class->perf_probe ||
-                     tp_event->class->reg) &&
+                    tp_event->class && tp_event->class->reg &&
                     try_module_get(tp_event->mod)) {
                         ret = perf_trace_event_init(tp_event, p_event);
                         break;
@@ -136,12 +128,7 @@ void perf_trace_destroy(struct perf_event *p_event)
         if (--tp_event->perf_refcount > 0)
                 goto out;
 
-        if (tp_event->class->reg)
-                tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
-        else
-                tracepoint_probe_unregister(tp_event->name,
-                                            tp_event->class->perf_probe,
-                                            tp_event);
+        tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
 
         /*
          * Ensure our callback won't be called anymore. See
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 69bee4cc0e10..e8e6043f4d29 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -141,6 +141,35 @@ int trace_event_raw_init(struct ftrace_event_call *call)
 }
 EXPORT_SYMBOL_GPL(trace_event_raw_init);
 
+int ftrace_event_reg(struct ftrace_event_call *call, enum trace_reg type)
+{
+        switch (type) {
+        case TRACE_REG_REGISTER:
+                return tracepoint_probe_register(call->name,
+                                                 call->class->probe,
+                                                 call);
+        case TRACE_REG_UNREGISTER:
+                tracepoint_probe_unregister(call->name,
+                                            call->class->probe,
+                                            call);
+                return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+        case TRACE_REG_PERF_REGISTER:
+                return tracepoint_probe_register(call->name,
+                                                 call->class->perf_probe,
+                                                 call);
+        case TRACE_REG_PERF_UNREGISTER:
+                tracepoint_probe_unregister(call->name,
+                                            call->class->perf_probe,
+                                            call);
+                return 0;
+#endif
+        }
+        return 0;
+}
+EXPORT_SYMBOL_GPL(ftrace_event_reg);
+
 static int ftrace_event_enable_disable(struct ftrace_event_call *call,
                                         int enable)
 {
@@ -151,23 +180,13 @@ static int ftrace_event_enable_disable(struct ftrace_event_call *call,
                 if (call->flags & TRACE_EVENT_FL_ENABLED) {
                         call->flags &= ~TRACE_EVENT_FL_ENABLED;
                         tracing_stop_cmdline_record();
-                        if (call->class->reg)
-                                call->class->reg(call, TRACE_REG_UNREGISTER);
-                        else
-                                tracepoint_probe_unregister(call->name,
-                                                            call->class->probe,
-                                                            call);
+                        call->class->reg(call, TRACE_REG_UNREGISTER);
                 }
                 break;
         case 1:
                 if (!(call->flags & TRACE_EVENT_FL_ENABLED)) {
                         tracing_start_cmdline_record();
-                        if (call->class->reg)
-                                ret = call->class->reg(call, TRACE_REG_REGISTER);
-                        else
-                                ret = tracepoint_probe_register(call->name,
-                                                                call->class->probe,
-                                                                call);
+                        ret = call->class->reg(call, TRACE_REG_REGISTER);
                         if (ret) {
                                 tracing_stop_cmdline_record();
                                 pr_info("event trace: Could not enable event "
@@ -205,8 +224,7 @@ static int __ftrace_set_clr_event(const char *match, const char *sub,
         mutex_lock(&event_mutex);
         list_for_each_entry(call, &ftrace_events, list) {
 
-                if (!call->name || !call->class ||
-                    (!call->class->probe && !call->class->reg))
+                if (!call->name || !call->class || !call->class->reg)
                         continue;
 
                 if (match &&
@@ -332,7 +350,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
                  * The ftrace subsystem is for showing formats only.
                  * They can not be enabled or disabled via the event files.
                  */
-                if (call->class && (call->class->probe || call->class->reg))
+                if (call->class && call->class->reg)
                         return call;
         }
 
@@ -485,8 +503,7 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 
         mutex_lock(&event_mutex);
         list_for_each_entry(call, &ftrace_events, list) {
-                if (!call->name || !call->class ||
-                    (!call->class->probe && !call->class->reg))
+                if (!call->name || !call->class || !call->class->reg)
                         continue;
 
                 if (system && strcmp(call->class->system, system) != 0)
@@ -977,12 +994,12 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
                 return -1;
         }
 
-        if (call->class->probe || call->class->reg)
+        if (call->class->reg)
                 trace_create_file("enable", 0644, call->dir, call,
                                   enable);
 
 #ifdef CONFIG_PERF_EVENTS
-        if (call->event.type && (call->class->perf_probe || call->class->reg))
+        if (call->event.type && call->class->reg)
                 trace_create_file("id", 0444, call->dir, call,
                                   id);
 #endif