tracing: Add synth_event_delete()

create_or_delete_synth_event() contains code to delete a synthetic
event, which would be useful on its own - specifically, it would be
useful to allow event-creating modules to call it separately.

Separate out the delete code from that function and create an exported
function named synth_event_delete().

Link: http://lkml.kernel.org/r/050db3b06df7f0a4b8a2922da602d1d879c7c1c2.1580323897.git.zanussi@kernel.org
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 8d621a7..25fe743 100644 (file)
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -354,6 +354,8 @@ extern struct trace_event_file *trace_get_event_file(const char *instance,
                                                     const char *event);
 extern void trace_put_event_file(struct trace_event_file *file);
 
+extern int synth_event_delete(const char *name);
+
 /*
  * Event file flags:
  *  ENABLED      - The event is enabled

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index c322826..21e3167 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1360,29 +1360,54 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
        goto out;
 }
 
+static int destroy_synth_event(struct synth_event *se)
+{
+       int ret;
+
+       if (se->ref)
+               ret = -EBUSY;
+       else {
+               ret = unregister_synth_event(se);
+               if (!ret) {
+                       dyn_event_remove(&se->devent);
+                       free_synth_event(se);
+               }
+       }
+
+       return ret;
+}
+
+/**
+ * synth_event_delete - Delete a synthetic event
+ * @event_name: The name of the new sythetic event
+ *
+ * Delete a synthetic event that was created with synth_event_create().
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int synth_event_delete(const char *event_name)
+{
+       struct synth_event *se = NULL;
+       int ret = -ENOENT;
+
+       mutex_lock(&event_mutex);
+       se = find_synth_event(event_name);
+       if (se)
+               ret = destroy_synth_event(se);
+       mutex_unlock(&event_mutex);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(synth_event_delete);
+
 static int create_or_delete_synth_event(int argc, char **argv)
 {
        const char *name = argv[0];
-       struct synth_event *event = NULL;
        int ret;
 
        /* trace_run_command() ensures argc != 0 */
        if (name[0] == '!') {
-               mutex_lock(&event_mutex);
-               event = find_synth_event(name + 1);
-               if (event) {
-                       if (event->ref)
-                               ret = -EBUSY;
-                       else {
-                               ret = unregister_synth_event(event);
-                               if (!ret) {
-                                       dyn_event_remove(&event->devent);
-                                       free_synth_event(event);
-                               }
-                       }
-               } else
-                       ret = -ENOENT;
-               mutex_unlock(&event_mutex);
+               ret = synth_event_delete(name + 1);
                return ret;
        }