1 files changed, 33 insertions, 6 deletions

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 73956eaff8a9..26efd22f0633 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -221,6 +221,29 @@ static void *func_remove(struct tracepoint_func **funcs,
 	return old;
 }
 
+static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs, bool sync)
+{
+	void *func = tp->iterator;
+
+	/* Synthetic events do not have static call sites */
+	if (!tp->static_call_key)
+		return;
+
+	if (!tp_funcs[1].func) {
+		func = tp_funcs[0].func;
+		/*
+		 * If going from the iterator back to a single caller,
+		 * we need to synchronize with __DO_TRACE to make sure
+		 * that the data passed to the callback is the one that
+		 * belongs to that callback.
+		 */
+		if (sync)
+			tracepoint_synchronize_unregister();
+	}
+
+	__static_call_update(tp->static_call_key, tp->static_call_tramp, func);
+}
+
 /*
  * Add the probe function to a tracepoint.
  */
@@ -251,8 +274,9 @@ static int tracepoint_add_func(struct tracepoint *tp,
 	 * include/linux/tracepoint.h using rcu_dereference_sched().
 	 */
 	rcu_assign_pointer(tp->funcs, tp_funcs);
-	if (!static_key_enabled(&tp->key))
-		static_key_slow_inc(&tp->key);
+	tracepoint_update_call(tp, tp_funcs, false);
+	static_key_enable(&tp->key);
+
 	release_probes(old);
 	return 0;
 }
@@ -281,10 +305,13 @@ static int tracepoint_remove_func(struct tracepoint *tp,
 		if (tp->unregfunc && static_key_enabled(&tp->key))
 			tp->unregfunc();
 
-		if (static_key_enabled(&tp->key))
-			static_key_slow_dec(&tp->key);
+		static_key_disable(&tp->key);
+		rcu_assign_pointer(tp->funcs, tp_funcs);
+	} else {
+		rcu_assign_pointer(tp->funcs, tp_funcs);
+		tracepoint_update_call(tp, tp_funcs,
+				       tp_funcs[0].func != old[0].func);
 	}
-	rcu_assign_pointer(tp->funcs, tp_funcs);
 	release_probes(old);
 	return 0;
 }
@@ -521,7 +548,7 @@ static int tracepoint_module_notify(struct notifier_block *self,
 	case MODULE_STATE_UNFORMED:
 		break;
 	}
-	return ret;
+	return notifier_from_errno(ret);
 }
 
 static struct notifier_block tracepoint_module_nb = {