Fix a name and a bug.

Function conn_list_empty_p() should have been conn_list_any_p().

Newly-allocated conns should be empty lists, as should newly-removed
conns. So set their prev and next pointers to themselves.

conn.c

@@ -16,7 +16,7 @@ int cur_conn_ct = 0, cur_worker_ct = 0, cur_producer_ct = 0;
 static int
 pool_conn_p()
 {
- return conn_list_empty_p(&pool);
+ return conn_list_any_p(&pool);
 }
 
 static conn
@@ -54,6 +54,7 @@ make_conn(int fd, char start_state)
  c->cmd_read = 0;
  c->in_job = c->out_job = c->reserved_job = NULL;
  c->in_job_read = c->out_job_sent = 0;
+ c->prev = c->next = c; /* must be out of a linked list right now */
 
  cur_conn_ct++; /* stats */
 
@@ -126,26 +127,26 @@ conn_update_evq(conn c, const int events)
 }
 
 int
-conn_list_empty_p(conn head)
+conn_list_any_p(conn head)
 {
- return head->next != head;
+ return head->next != head || head->prev != head;
 }
 
 void
 conn_remove(conn c)
 {
- if (!c->next || !c->prev) return; /* not in a doubly-linked list */
+ if (!conn_list_any_p(c)) return; /* not in a doubly-linked list */
 
  c->next->prev = c->prev;
  c->prev->next = c->next;
 
- c->prev = c->next = NULL;
+ c->prev = c->next = c;
 }
 
 void
 conn_insert(conn head, conn c)
 {
- if (c->prev || c->next) return; /* already in a linked list */
+ if (conn_list_any_p(c)) return; /* already in a linked list */
 
  c->prev = head->prev;
  c->next = head;

conn.h

@@ -66,7 +66,7 @@ int conn_update_evq(conn c, const int flags);
 
 void conn_close(conn c);
 
-int conn_list_empty_p(conn head);
+int conn_list_any_p(conn head);
 void conn_remove(conn c);
 void conn_insert(conn head, conn c);
 

prot.c

@@ -17,7 +17,7 @@ static struct conn wait_queue = { &wait_queue, &wait_queue, 0 };
 static int
 waiting_conn_p()
 {
- return conn_list_empty_p(&wait_queue);
+ return conn_list_any_p(&wait_queue);
 }
 
 void