tracing: Simplify creation and deletion of synthetic events

Since the event_mutex and synth_event_mutex ordering issue
is gone, we can skip existing event check when adding or
deleting events, and some redundant code in error path.

This changes release_all_synth_events() to abort the process
when it hits any error and returns the error code. It succeeds
only if it has no error.

Link: http://lkml.kernel.org/r/154140847194.17322.17960275728005067803.stgit@devbox
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1670c65389fe91bbfb63b5072de23693e7785181..0feb7f460123aa4b1797de7dfaaf8e7aba243b96 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1008,18 +1008,6 @@ struct hist_var_data {
        struct hist_trigger_data *hist_data;
 };
 
-static void add_or_delete_synth_event(struct synth_event *event, int delete)
-{
-       if (delete)
-               free_synth_event(event);
-       else {
-               if (!find_synth_event(event->name))
-                       list_add(&event->list, &synth_event_list);
-               else
-                       free_synth_event(event);
-       }
-}
-
 static int create_synth_event(int argc, char **argv)
 {
        struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
@@ -1052,15 +1040,16 @@ static int create_synth_event(int argc, char **argv)
        if (event) {
                if (delete_event) {
                        if (event->ref) {
-                               event = NULL;
                                ret = -EBUSY;
                                goto out;
                        }
-                       list_del(&event->list);
-                       goto out;
-               }
-               event = NULL;
-               ret = -EEXIST;
+                       ret = unregister_synth_event(event);
+                       if (!ret) {
+                               list_del(&event->list);
+                               free_synth_event(event);
+                       }
+               } else
+                       ret = -EEXIST;
                goto out;
        } else if (delete_event) {
                ret = -ENOENT;
@@ -1100,29 +1089,21 @@ static int create_synth_event(int argc, char **argv)
                event = NULL;
                goto err;
        }
+       ret = register_synth_event(event);
+       if (!ret)
+               list_add(&event->list, &synth_event_list);
+       else
+               free_synth_event(event);
  out:
-       if (event) {
-               if (delete_event) {
-                       ret = unregister_synth_event(event);
-                       add_or_delete_synth_event(event, !ret);
-               } else {
-                       ret = register_synth_event(event);
-                       add_or_delete_synth_event(event, ret);
-               }
-       }
        mutex_unlock(&synth_event_mutex);
        mutex_unlock(&event_mutex);
 
        return ret;
  err:
-       mutex_unlock(&synth_event_mutex);
-       mutex_unlock(&event_mutex);
-
        for (i = 0; i < n_fields; i++)
                free_synth_field(fields[i]);
-       free_synth_event(event);
 
-       return ret;
+       goto out;
 }
 
 static int release_all_synth_events(void)
@@ -1141,10 +1122,12 @@ static int release_all_synth_events(void)
        }
 
        list_for_each_entry_safe(event, e, &synth_event_list, list) {
-               list_del(&event->list);
-
                ret = unregister_synth_event(event);
-               add_or_delete_synth_event(event, !ret);
+               if (!ret) {
+                       list_del(&event->list);
+                       free_synth_event(event);
+               } else
+                       break;
        }
        mutex_unlock(&synth_event_mutex);
        mutex_unlock(&event_mutex);