+
+/*
+ * Rotate a kernel session.
+ *
+ * Return 0 on success or else return a LTTNG_ERR code.
+ */
+int kernel_rotate_session(struct ltt_session *session)
+{
+ int ret;
+ struct consumer_socket *socket;
+ struct lttng_ht_iter iter;
+ struct ltt_kernel_session *ksess = session->kernel_session;
+
+ assert(ksess);
+ assert(ksess->consumer);
+
+ DBG("Rotate kernel session %s started (session %" PRIu64 ")",
+ session->name, session->id);
+
+ rcu_read_lock();
+
+ /*
+ * Note that this loop will end after one iteration given that there is
+ * only one kernel consumer.
+ */
+ cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
+ socket, node.node) {
+ struct ltt_kernel_channel *chan;
+
+ /*
+ * Account the metadata channel first to make sure the
+ * number of channels waiting for a rotation cannot
+ * reach 0 before we complete the iteration over all
+ * the channels.
+ */
+ ret = rotate_add_channel_pending(ksess->metadata->key,
+ LTTNG_DOMAIN_KERNEL, session);
+ if (ret < 0) {
+ ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+ goto error;
+ }
+
+ /* For each channel, ask the consumer to rotate it. */
+ cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
+ ret = rotate_add_channel_pending(chan->key,
+ LTTNG_DOMAIN_KERNEL, session);
+ if (ret < 0) {
+ ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+ goto error;
+ }
+
+ DBG("Rotate channel %" PRIu64 ", session %s", chan->key, session->name);
+ ret = consumer_rotate_channel(socket, chan->key,
+ ksess->uid, ksess->gid, ksess->consumer,
+ ksess->consumer->subdir,
+ /* is_metadata_channel */ false,
+ session->current_archive_id,
+ &session->rotate_pending_relay);
+ if (ret < 0) {
+ ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+ goto error;
+ }
+ }
+
+ /*
+ * Rotate the metadata channel.
+ */
+ ret = consumer_rotate_channel(socket, ksess->metadata->key,
+ ksess->uid, ksess->gid, ksess->consumer,
+ ksess->consumer->subdir,
+ /* is_metadata_channel */ true,
+ session->current_archive_id,
+ &session->rotate_pending_relay);
+ if (ret < 0) {
+ ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
+ goto error;
+ }
+ }
+
+ ret = LTTNG_OK;
+
+error:
+ rcu_read_unlock();
+ return ret;
+}