i guess it should have been written in the original code comments, but the hash table here is implemented with separate chaining via singly linked lists, as seen here: 

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Hash_table_5_0_1_1_1_1_1_LL.svg/500px-Hash_table_5_0_1_1_1_1_1_LL.svg.png

i.e. each of the "entries" in the diagram is implemented here as a singly linked list

the linked list nodes are "tvm_htab_node_t" structures (indeed they have "next" pointers)
the array of bucket-lists is a "tvm_htab_t" structure