2 files changed, 61 insertions, 11 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 07e0a6d64a24..78a9ba24cbf6 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -56,6 +56,7 @@ typedef enum print_line_t (*trace_print_func)(struct trace_iterator *iter,
                                               int flags);
 struct trace_event {
         struct hlist_node       node;
+        struct list_head        list;
         int                     type;
         trace_print_func        trace;
         trace_print_func        raw;
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 06997e75114b..5fc51f0f75fc 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -483,6 +483,36 @@ struct trace_event *ftrace_find_event(int type)
         return NULL;
 }
 
+static LIST_HEAD(ftrace_event_list);
+
+static int trace_search_list(struct list_head **list)
+{
+        struct trace_event *e;
+        int last = __TRACE_LAST_TYPE;
+
+        if (list_empty(&ftrace_event_list)) {
+                *list = &ftrace_event_list;
+                return last + 1;
+        }
+
+        /*
+         * We used up all possible max events,
+         * lets see if somebody freed one.
+         */
+        list_for_each_entry(e, &ftrace_event_list, list) {
+                if (e->type != last + 1)
+                        break;
+                last++;
+        }
+
+        /* Did we used up all 65 thousand events??? */
+        if ((last + 1) > FTRACE_MAX_EVENT)
+                return 0;
+
+        *list = &e->list;
+        return last + 1;
+}
+
 /**
  * register_ftrace_event - register output for an event type
  * @event: the event type to register
@@ -505,20 +535,40 @@ int register_ftrace_event(struct trace_event *event)
 
         mutex_lock(&trace_event_mutex);
 
-        if (!event) {
-                ret = next_event_type++;
+        if (WARN_ON(!event))
                 goto out;
-        }
 
-        if (!event->type)
-                event->type = next_event_type++;
-        else if (event->type > __TRACE_LAST_TYPE) {
+        INIT_LIST_HEAD(&event->list);
+
+        if (!event->type) {
+                struct list_head *list;
+
+                if (next_event_type > FTRACE_MAX_EVENT) {
+
+                        event->type = trace_search_list(&list);
+                        if (!event->type)
+                                goto out;
+
+                } else {
+                        
+                        event->type = next_event_type++;
+                        list = &ftrace_event_list;
+                }
+
+                if (WARN_ON(ftrace_find_event(event->type)))
+                        goto out;
+
+                list_add_tail(&event->list, list);
+
+        } else if (event->type > __TRACE_LAST_TYPE) {
                 printk(KERN_WARNING "Need to add type to trace.h\n");
                 WARN_ON(1);
-        }
-
-        if (ftrace_find_event(event->type))
                 goto out;
+        } else {
+                /* Is this event already used */
+                if (ftrace_find_event(event->type))
+                        goto out;
+        }
 
         if (event->trace == NULL)
                 event->trace = trace_nop_print;
@@ -537,8 +587,6 @@ int register_ftrace_event(struct trace_event *event)
  out:
         mutex_unlock(&trace_event_mutex);
 
-        WARN_ON_ONCE(next_event_type > FTRACE_MAX_EVENT);
-
         return ret;
 }
 EXPORT_SYMBOL_GPL(register_ftrace_event);
@@ -551,6 +599,7 @@ int unregister_ftrace_event(struct trace_event *event)
 {
         mutex_lock(&trace_event_mutex);
         hlist_del(&event->node);
+        list_del(&event->list);
         mutex_unlock(&trace_event_mutex);
 
         return 0;