Warn on event registration/unregistration failure

Warn whenever event registration/unregistration fails, including when
synchonizing the event list.

Silently ignoring errors makes identification of those failures tricky.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I764455c8535ddb906325942e70aa689ca21c04bb

diff --git a/src/lttng-events.c b/src/lttng-events.c
index 230e393446735edcfaef947c274a39faa0d6f891..31c1145748361ee894992b293505597348ce032b 100644 (file)
--- a/src/lttng-events.c
+++ b/src/lttng-events.c
@@ -72,8 +72,8 @@ static void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier
 
 static void _lttng_event_destroy(struct lttng_kernel_event_common *event);
 static void _lttng_channel_destroy(struct lttng_kernel_channel_buffer *chan);
-static int _lttng_event_unregister(struct lttng_kernel_event_recorder *event);
-static int _lttng_event_notifier_unregister(struct lttng_kernel_event_notifier *event_notifier);
+static void _lttng_event_unregister(struct lttng_kernel_event_recorder *event);
+static void _lttng_event_notifier_unregister(struct lttng_kernel_event_notifier *event_notifier);
 static
 int _lttng_event_metadata_statedump(struct lttng_kernel_session *session,
                                  struct lttng_kernel_channel_buffer *chan,
@@ -364,10 +364,8 @@ void lttng_session_destroy(struct lttng_kernel_session *session)
                ret = lttng_syscalls_unregister_channel(chan_priv->pub);
                WARN_ON(ret);
        }
-       list_for_each_entry(event_recorder_priv, &session->priv->events, node) {
-               ret = _lttng_event_unregister(event_recorder_priv->pub);
-               WARN_ON(ret);
-       }
+       list_for_each_entry(event_recorder_priv, &session->priv->events, node)
+               _lttng_event_unregister(event_recorder_priv->pub);
        synchronize_trace();    /* Wait for in-flight events to complete */
        list_for_each_entry(chan_priv, &session->priv->chan, node) {
                ret = lttng_syscalls_destroy_event(chan_priv->pub);
@@ -415,10 +413,8 @@ void lttng_event_notifier_group_destroy(
        WARN_ON(ret);
 
        list_for_each_entry_safe(event_notifier_priv, tmpevent_notifier_priv,
-                       &event_notifier_group->event_notifiers_head, node) {
-               ret = _lttng_event_notifier_unregister(event_notifier_priv->pub);
-               WARN_ON(ret);
-       }
+                       &event_notifier_group->event_notifiers_head, node)
+               _lttng_event_notifier_unregister(event_notifier_priv->pub);
 
        /* Wait for in-flight event notifier to complete */
        synchronize_trace();
@@ -1432,8 +1428,7 @@ void register_event(struct lttng_kernel_event_recorder *event_recorder)
        const struct lttng_kernel_event_desc *desc;
        int ret = -EINVAL;
 
-       if (event_recorder->priv->parent.registered)
-               return;
+       WARN_ON_ONCE(event_recorder->priv->parent.registered);
 
        desc = event_recorder->priv->parent.desc;
        switch (event_recorder->priv->parent.instrumentation) {
@@ -1469,14 +1464,14 @@ void register_event(struct lttng_kernel_event_recorder *event_recorder)
 /*
  * Only used internally at session destruction.
  */
-int _lttng_event_unregister(struct lttng_kernel_event_recorder *event_recorder)
+static
+void unregister_event(struct lttng_kernel_event_recorder *event_recorder)
 {
        struct lttng_kernel_event_common_private *event_priv = &event_recorder->priv->parent;
        const struct lttng_kernel_event_desc *desc;
        int ret = -EINVAL;
 
-       if (!event_priv->registered)
-               return 0;
+       WARN_ON_ONCE(!event_priv->registered);
 
        desc = event_priv->desc;
        switch (event_priv->instrumentation) {
@@ -1514,9 +1509,16 @@ int _lttng_event_unregister(struct lttng_kernel_event_recorder *event_recorder)
        default:
                WARN_ON_ONCE(1);
        }
+       WARN_ON_ONCE(ret);
        if (!ret)
                event_priv->registered = 0;
-       return ret;
+}
+
+static
+void _lttng_event_unregister(struct lttng_kernel_event_recorder *event_recorder)
+{
+       if (event_recorder->priv->parent.registered)
+               unregister_event(event_recorder);
 }
 
 /* Only used for tracepoints for now. */
@@ -1526,8 +1528,7 @@ void register_event_notifier(struct lttng_kernel_event_notifier *event_notifier)
        const struct lttng_kernel_event_desc *desc;
        int ret = -EINVAL;
 
-       if (event_notifier->priv->parent.registered)
-               return;
+       WARN_ON_ONCE(event_notifier->priv->parent.registered);
 
        desc = event_notifier->priv->parent.desc;
        switch (event_notifier->priv->parent.instrumentation) {
@@ -1561,14 +1562,12 @@ void register_event_notifier(struct lttng_kernel_event_notifier *event_notifier)
 }
 
 static
-int _lttng_event_notifier_unregister(
-               struct lttng_kernel_event_notifier *event_notifier)
+int unregister_event_notifier(struct lttng_kernel_event_notifier *event_notifier)
 {
        const struct lttng_kernel_event_desc *desc;
        int ret = -EINVAL;
 
-       if (!event_notifier->priv->parent.registered)
-               return 0;
+       WARN_ON_ONCE(!event_notifier->priv->parent.registered);
 
        desc = event_notifier->priv->parent.desc;
        switch (event_notifier->priv->parent.instrumentation) {
@@ -1606,6 +1605,13 @@ int _lttng_event_notifier_unregister(
        return ret;
 }
 
+static
+void _lttng_event_notifier_unregister(struct lttng_kernel_event_notifier *event_notifier)
+{
+       if (event_notifier->priv->parent.registered)
+               unregister_event_notifier(event_notifier);
+}
+
 /*
  * Only used internally at session destruction.
  */
@@ -2784,9 +2790,11 @@ void lttng_session_sync_event_enablers(struct lttng_kernel_session *session)
                 * state.
                 */
                if (enabled) {
-                       register_event(event_recorder);
+                       if (!event_recorder_priv->parent.registered)
+                               register_event(event_recorder);
                } else {
-                       _lttng_event_unregister(event_recorder);
+                       if (event_recorder_priv->parent.registered)
+                               _lttng_event_unregister(event_recorder);
                }
 
                /* Check if has enablers without bytecode enabled */
@@ -2877,7 +2885,7 @@ void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group
                                register_event_notifier(event_notifier);
                } else {
                        if (event_notifier_priv->parent.registered)
-                               _lttng_event_notifier_unregister(event_notifier);
+                               unregister_event_notifier(event_notifier);
                }
 
                /* Check if has enablers without bytecode enabled */