Merge 2af2e3e799 into 2e5b0412f9

Follow-up for 2b07a3211b.

Fixes the failure found in
https://autopkgtest.ubuntu.com/results/autopkgtest-noble-upstream-systemd-ci-systemd-ci/noble/amd64/s/systemd-upstream/20241115_182040_92382@/log.gz
. Relevant logs:
```
Nov 16 02:48:36 systemd-networkd[2706]: veth99: Reconfiguring with /run/systemd/network/25-dhcp-client-ipv6-only.network.
Nov 16 02:48:36 systemd-networkd[2706]: veth99: NDISC: Started IPv6 Router Solicitation client
Nov 16 02:48:36 systemd-networkd[2706]: veth99: IPv6 Router Discovery is configured and started.
Nov 16 02:48:36 systemd-networkd[2706]: veth99: NDISC: Sent Router Solicitation, next solicitation in 3s
Nov 16 02:48:36 systemd-networkd[2706]: veth99: NDISC: Received Router Advertisement from fe80::1034:56ff:fe78:9abd: flags=0xc0(managed, other), preference=medium, lifetime=30min
Nov 16 02:48:36 systemd-networkd[2706]: veth99: NDISC: Invoking callback for 'router' event.
Nov 16 02:48:36 systemd-networkd[2706]: veth99: link_check_ready(): dynamic addressing protocols are enabled but none of them finished yet.
Nov 16 02:48:36 systemd-networkd[2706]: veth99: DHCPv6 client: Starting in Solicit mode
Nov 16 02:48:36 systemd-networkd[2706]: veth99: DHCPv6 client: State changed: stopped -> solicitation
Nov 16 02:48:36 systemd-networkd[2706]: veth99: Acquiring DHCPv6 lease on NDisc request
Nov 16 02:48:36 systemd-networkd[2706]: veth99: DHCPv6 client: Sent Solicit
Nov 16 02:48:36 systemd-networkd[2706]: veth99: DHCPv6 client: Next retransmission in 1s
Nov 16 02:48:37 systemd-networkd[2706]: veth99: DHCPv6 client: Sent Solicit
Nov 16 02:48:37 systemd-networkd[2706]: veth99: DHCPv6 client: Next retransmission in 1s
Nov 16 02:48:39 systemd-networkd[2706]: veth99: NDISC: Received Neighbor Advertisement from fe80::1034:56ff:fe78:9abd: Router=yes, Solicited=yes, Override=no
Nov 16 02:48:39 systemd-networkd[2706]: veth99: NDISC: Invoking callback for 'neighbor' event.
Nov 16 02:48:39 systemd-networkd[2706]: veth99: DHCPv6 client: Processed Reply message
Nov 16 02:48:39 systemd-networkd[2706]: veth99: DHCPv6 client: T1 expires in 50s
Nov 16 02:48:39 systemd-networkd[2706]: veth99: DHCPv6 client: T2 expires in 55s
Nov 16 02:48:39 systemd-networkd[2706]: veth99: DHCPv6 client: Valid lifetime expires in 2min
Nov 16 02:48:39 systemd-networkd[2706]: veth99: DHCPv6 client: State changed: solicitation -> bound
Nov 16 02:48:39 systemd-networkd[2706]: veth99: DHCPv6 address 2600::15/128 (valid for 1min 59s, preferred for 1min 59s)
Nov 16 02:48:41 systemd-networkd[2706]: veth99: Received updated DHCPv6 address (configured): 2600::15/128 (valid for 1min 58s, preferred for 1min 58s), flags: no-prefixroute, scope: global
Nov 16 02:48:41 systemd-networkd[2706]: veth99: DHCPv6 addresses and routes set.
Nov 16 02:48:41 systemd-networkd[2706]: veth99: link_check_ready(): IPv4LL:no DHCPv4:no DHCPv6:yes DHCP-PD:no NDisc:no
Nov 16 02:48:41 systemd-networkd[2706]: veth99: State changed: configuring -> configured
```
The interface veth99 entered the configured state after 5 seconds, but
at the same time, the `wait_online()` in the test script considered the
test failed.
The function `wait_online()` first invokes
`systemd-networkd-wait-online` with `--timeout=20`, then check setup
states of interfaces with 5 seconds timeout. So, the failure suggests
that `systemd-networkd-wait-online` finishes immediately, as the state
file was not updated when it is invoked, and thus it handles the
interface veth99 already in the configured state.

src/libsystemd/sd-varlink/sd-varlink.c

@@ -1698,7 +1698,8 @@ _public_ int sd_varlink_get_events(sd_varlink *v) {
                 ret |= EPOLLIN;
 
         if (!v->write_disconnected &&
-            v->output_buffer_size > 0)
+            (v->output_queue ||
+             v->output_buffer_size > 0))
                 ret |= EPOLLOUT;
 
         return ret;

src/network/networkd-link.c

@@ -1443,6 +1443,7 @@ int link_reconfigure_impl(Link *link, LinkReconfigurationFlag flags) {
 }
 
 typedef struct LinkReconfigurationData {
+        Manager *manager;
         Link *link;
         LinkReconfigurationFlag flags;
         sd_bus_message *message;
@@ -1473,6 +1474,12 @@ static void link_reconfiguration_data_destroy_callback(LinkReconfigurationData *
                 }
 
                 if (!data->counter || *data->counter <= 0) {
+                        /* Update the state files before replying the bus method. Otherwise,
+                         * systemd-networkd-wait-online following networkctl reload/reconfigure may read an
+                         * outdated state file and wrongly handle an interface is already in the configured
+                         * state. */
+                        (void) manager_clean_all(data->manager);
+
                         r = sd_bus_reply_method_return(data->message, NULL);
                         if (r < 0)
                                 log_warning_errno(r, "Failed to reply for DBus method, ignoring: %m");
@@ -1521,6 +1528,7 @@ int link_reconfigure_full(Link *link, LinkReconfigurationFlag flags, sd_bus_mess
         }
 
         *data = (LinkReconfigurationData) {
+                .manager = link->manager,
                 .link = link_ref(link),
                 .flags = flags,
                 .message = sd_bus_message_ref(message), /* message may be NULL, but _ref() works fine. */

test/test-network/systemd-networkd-tests.py

@@ -6406,11 +6406,11 @@ class NetworkdRATests(unittest.TestCase, Utilities):
 
         for i in [100, 200, 300, 512, 1024, 2048]:
             if i not in [metric_1, metric_2]:
-                self.assertNotIn(f'{i}', output)
+                self.assertNotIn(f'metric {i} ', output)
 
         for i in ['low', 'medium', 'high']:
             if i not in [preference_1, preference_2]:
-                self.assertNotIn(f'{i}', output)
+                self.assertNotIn(f'pref {i}', output)
 
     def test_router_preference(self):
         copy_network_unit('25-veth-client.netdev',