+/*
+ * Called with session lock held.
+ */
+ssize_t trace_ust_list_tracker_pids(struct ltt_ust_session *session,
+ int32_t **_pids)
+{
+ struct ust_pid_tracker_node *tracker_node;
+ struct lttng_ht_iter iter;
+ unsigned long count, i = 0;
+ long approx[2];
+ int32_t *pids;
+ int ret = 0;
+
+ if (!session->pid_tracker.ht) {
+ /* Tracker disabled. Set first entry to -1. */
+ pids = zmalloc(sizeof(*pids));
+ if (!pids) {
+ ret = -1;
+ goto end;
+ }
+ pids[0] = -1;
+ *_pids = pids;
+ return 1;
+ }
+
+ rcu_read_lock();
+ cds_lfht_count_nodes(session->pid_tracker.ht->ht,
+ &approx[0], &count, &approx[1]);
+ pids = zmalloc(sizeof(*pids) * count);
+ if (!pids) {
+ ret = -1;
+ goto end;
+ }
+ cds_lfht_for_each_entry(session->pid_tracker.ht->ht,
+ &iter.iter, tracker_node, node.node) {
+ pids[i++] = tracker_node->node.key;
+ }
+ *_pids = pids;
+ ret = count;
+end:
+ rcu_read_unlock();
+ return ret;
+}
+