The loop in shutdown_listener() assumes that the reference count for
every controlconnection_t object on the listener->connections linked
list will drop down to zero after the conn_shutdown() call in the loop's
body. However, when the timing is just right, some netmgr callbacks for
a given control connection may still be awaiting processing by the same
event loop that executes shutdown_listener() when the latter is run.
Since these netmgr callbacks must be run in order for the reference
count for the relevant controlconnection_t objects to drop to zero, when
the scenario described above happens, shutdown_listener() runs into an
infinite loop due to one of the controlconnection_t objects on the
listener->connections linked list never going away from the head of that
list.
Fix by safely iterating through the listener->connections list and
initiating shutdown for all controlconnection_t objects found. This
allows any pending netmgr callbacks to be run by the same event loop in
due course, i.e. after shutdown_listener() returns.
Michał Kępień
2d75c96874