tracing/ftrace: Fix to check create_event_dir() when adding new events

Check result of event_create_dir() and add ftrace_event_call to
ftrace_events list only if it is succeeded. Thanks to Li for pointing
it out.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090925182054.10157.55219.stgit@omoto>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

kernel/trace/trace_events.c

@@ -957,12 +957,12 @@ static int __trace_add_event_call(struct ftrace_event_call *call)
 	if (!d_events)
 		return -ENOENT;
 
-	list_add(&call->list, &ftrace_events);
 	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)
-		list_del(&call->list);
+	if (!ret)
+		list_add(&call->list, &ftrace_events);
+
 	return ret;
 }
 
@@ -1124,10 +1124,11 @@ static void trace_module_add_events(struct module *mod)
 				return;
 		}
 		call->mod = mod;
-		list_add(&call->list, &ftrace_events);
-		event_create_dir(call, d_events,
-				 &file_ops->id, &file_ops->enable,
-				 &file_ops->filter, &file_ops->format);
+		ret = event_create_dir(call, d_events,
+				       &file_ops->id, &file_ops->enable,
+				       &file_ops->filter, &file_ops->format);
+		if (!ret)
+			list_add(&call->list, &ftrace_events);
 	}
 }
 
@@ -1267,10 +1268,12 @@ static __init int event_trace_init(void)
 				continue;
 			}
 		}
-		list_add(&call->list, &ftrace_events);
-		event_create_dir(call, d_events, &ftrace_event_id_fops,
-				 &ftrace_enable_fops, &ftrace_event_filter_fops,
-				 &ftrace_event_format_fops);
+		ret = event_create_dir(call, d_events, &ftrace_event_id_fops,
+				       &ftrace_enable_fops,
+				       &ftrace_event_filter_fops,
+				       &ftrace_event_format_fops);
+		if (!ret)
+			list_add(&call->list, &ftrace_events);
 	}
 
 	while (true) {