tracing: trace_remove_event_call() should fail if call/file is in use

[linux-imx.git] / kernel / trace / trace_events.c

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a67c913e2f9f148b7a857f5d9d27070ff003e8ea..ec04836273c00f78b6eea73f0093390324a4bd9c 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1713,16 +1713,47 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
        destroy_preds(call);
 }
 
+static int probe_remove_event_call(struct ftrace_event_call *call)
+{
+       struct trace_array *tr;
+       struct ftrace_event_file *file;
+
+#ifdef CONFIG_PERF_EVENTS
+       if (call->perf_refcount)
+               return -EBUSY;
+#endif
+       do_for_each_event_file(tr, file) {
+               if (file->event_call != call)
+                       continue;
+               /*
+                * We can't rely on ftrace_event_enable_disable(enable => 0)
+                * we are going to do, FTRACE_EVENT_FL_SOFT_MODE can suppress
+                * TRACE_REG_UNREGISTER.
+                */
+               if (file->flags & FTRACE_EVENT_FL_ENABLED)
+                       return -EBUSY;
+               break;
+       } while_for_each_event_file();
+
+       __trace_remove_event_call(call);
+
+       return 0;
+}
+
 /* Remove an event_call */
-void trace_remove_event_call(struct ftrace_event_call *call)
+int trace_remove_event_call(struct ftrace_event_call *call)
 {
+       int ret;
+
        mutex_lock(&trace_types_lock);
        mutex_lock(&event_mutex);
        down_write(&trace_event_sem);
-       __trace_remove_event_call(call);
+       ret = probe_remove_event_call(call);
        up_write(&trace_event_sem);
        mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);
+
+       return ret;
 }
 
 #define for_each_event(event, start, end)                      \