MEDIUM: listeners: always close master vs worker listeners

Right now in enable_listener(), we used to start all enabled
listeners then kill from the workers those that were for the master.
But this is incomplete. We must also close from the master the
listeners that are solely for workers, and do it before we even
start them. Otherwise we end up with a master responding to the
worker CLI connections if the listener remains in listen mode to
translate the socket's real state.

It doesn't seem like it could have caused bugs in the past because we
used to aggressively mark disabled listeners as LI_ASSIGNED despite
the fact that they were still bound and listening. If this patch were
ever seen as a candidate solution for any obscure bug, be careful in
that it subtly relies on the fact that fd_delete() doesn't close
inherited FDs anymore, otherwise that could break the master's ability
to pass inherited FDs on reloads.

diff --git a/src/listener.c b/src/listener.c
index 48fdc96bbadf7dd84a93edf989c531000d5f66e6..364d061ac7b76f445dc7e5deeefaac2c709648f3 100644 (file)
--- a/src/listener.c
+++ b/src/listener.c
@@ -282,6 +282,16 @@ void listener_set_state(struct listener *l, enum li_state st)
 void enable_listener(struct listener *listener)
 {
        HA_SPIN_LOCK(LISTENER_LOCK, &listener->lock);
+
+       /* If this listener is supposed to be only in the master, close it in
+        * the workers. Conversely, if it's supposed to be only in the workers
+        * close it in the master.
+        */
+       if ((master && !(listener->options & LI_O_MWORKER)) ||
+           (!master && (listener->options & LI_O_MWORKER))) {
+               do_unbind_listener(listener, 1);
+       }
+
        if (listener->state == LI_LISTEN) {
                BUG_ON(listener->rx.fd == -1);
                if ((global.mode & (MODE_DAEMON | MODE_MWORKER)) &&
@@ -304,12 +314,7 @@ void enable_listener(struct listener *listener)
                        listener_set_state(listener, LI_FULL);
                }
        }
-       /* if this listener is supposed to be only in the master, close it in the workers */
-       if ((global.mode & MODE_MWORKER) &&
-           (listener->options & LI_O_MWORKER) &&
-           master == 0) {
-               do_unbind_listener(listener, 1);
-       }
+
        HA_SPIN_UNLOCK(LISTENER_LOCK, &listener->lock);
 }