From c8bae3637212daad992323d4b2a253c3949c9777 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 07:24:17 +0900
Subject: [PATCH 1/8] libsystemd-network: do not request each daemon exist in
 sd_xxx_stop()

---
 src/libsystemd-network/sd-dhcp-client.c  | 5 +++--
 src/libsystemd-network/sd-dhcp-server.c  | 3 ++-
 src/libsystemd-network/sd-dhcp6-client.c | 3 ++-
 src/libsystemd-network/sd-ipv4acd.c      | 3 ++-
 src/libsystemd-network/sd-ipv4ll.c       | 3 ++-
 src/libsystemd-network/sd-lldp.c         | 3 ++-
 src/libsystemd-network/sd-ndisc.c        | 3 ++-
 src/libsystemd-network/sd-radv.c         | 3 ++-
 8 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 6eb3c1b7a0..53c4350874 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -2135,9 +2135,10 @@ int sd_dhcp_client_send_decline(sd_dhcp_client *client) {
 }
 
 int sd_dhcp_client_stop(sd_dhcp_client *client) {
-        DHCP_CLIENT_DONT_DESTROY(client);
+        if (!client)
+                return 0;
 
-        assert_return(client, -EINVAL);
+        DHCP_CLIENT_DONT_DESTROY(client);
 
         client_stop(client, SD_DHCP_CLIENT_EVENT_STOP);
         client->state = DHCP_STATE_STOPPED;
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index a34a55919e..9022aefccb 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -225,7 +225,8 @@ sd_event *sd_dhcp_server_get_event(sd_dhcp_server *server) {
 }
 
 int sd_dhcp_server_stop(sd_dhcp_server *server) {
-        assert_return(server, -EINVAL);
+        if (!server)
+                return 0;
 
         server->receive_message =
                 sd_event_source_unref(server->receive_message);
diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index e1dbdaff4e..6d27c4685e 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -1676,7 +1676,8 @@ static int client_start(sd_dhcp6_client *client, enum DHCP6State state) {
 }
 
 int sd_dhcp6_client_stop(sd_dhcp6_client *client) {
-        assert_return(client, -EINVAL);
+        if (!client)
+                return 0;
 
         client_stop(client, SD_DHCP6_CLIENT_EVENT_STOP);
 
diff --git a/src/libsystemd-network/sd-ipv4acd.c b/src/libsystemd-network/sd-ipv4acd.c
index ecd91cd927..ff333914e9 100644
--- a/src/libsystemd-network/sd-ipv4acd.c
+++ b/src/libsystemd-network/sd-ipv4acd.c
@@ -144,7 +144,8 @@ static void ipv4acd_client_notify(sd_ipv4acd *acd, int event) {
 int sd_ipv4acd_stop(sd_ipv4acd *acd) {
         IPv4ACDState old_state;
 
-        assert_return(acd, -EINVAL);
+        if (!acd)
+                return 0;
 
         old_state = acd->state;
 
diff --git a/src/libsystemd-network/sd-ipv4ll.c b/src/libsystemd-network/sd-ipv4ll.c
index 4f4d9ebe87..293a4644a2 100644
--- a/src/libsystemd-network/sd-ipv4ll.c
+++ b/src/libsystemd-network/sd-ipv4ll.c
@@ -89,7 +89,8 @@ int sd_ipv4ll_new(sd_ipv4ll **ret) {
 }
 
 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
-        assert_return(ll, -EINVAL);
+        if (!ll)
+                return 0;
 
         return sd_ipv4acd_stop(ll->acd);
 }
diff --git a/src/libsystemd-network/sd-lldp.c b/src/libsystemd-network/sd-lldp.c
index b0a11fe20b..e536f90d19 100644
--- a/src/libsystemd-network/sd-lldp.c
+++ b/src/libsystemd-network/sd-lldp.c
@@ -276,7 +276,8 @@ fail:
 }
 
 _public_ int sd_lldp_stop(sd_lldp *lldp) {
-        assert_return(lldp, -EINVAL);
+        if (!lldp)
+                return 0;
 
         if (lldp->fd < 0)
                 return 0;
diff --git a/src/libsystemd-network/sd-ndisc.c b/src/libsystemd-network/sd-ndisc.c
index 9922203ac4..92e772d352 100644
--- a/src/libsystemd-network/sd-ndisc.c
+++ b/src/libsystemd-network/sd-ndisc.c
@@ -321,7 +321,8 @@ static int ndisc_timeout_no_ra(sd_event_source *s, uint64_t usec, void *userdata
 }
 
 _public_ int sd_ndisc_stop(sd_ndisc *nd) {
-        assert_return(nd, -EINVAL);
+        if (!nd)
+                return 0;
 
         if (nd->fd < 0)
                 return 0;
diff --git a/src/libsystemd-network/sd-radv.c b/src/libsystemd-network/sd-radv.c
index 016808667c..9656d7c969 100644
--- a/src/libsystemd-network/sd-radv.c
+++ b/src/libsystemd-network/sd-radv.c
@@ -353,7 +353,8 @@ fail:
 _public_ int sd_radv_stop(sd_radv *ra) {
         int r;
 
-        assert_return(ra, -EINVAL);
+        if (!ra)
+                return 0;
 
         if (ra->state == SD_RADV_STATE_IDLE)
                 return 0;

From 84add3cd2b4b590d993b04b83aaedd20439ea4b2 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 07:38:45 +0900
Subject: [PATCH 2/8] network: drop conditions to check existence of each
 engine

---
 src/network/networkd-address.c |  3 ---
 src/network/networkd-dhcp4.c   |  3 +--
 src/network/networkd-link.c    | 48 +++++++++++++---------------------
 3 files changed, 19 insertions(+), 35 deletions(-)

diff --git a/src/network/networkd-address.c b/src/network/networkd-address.c
index a6f8bcac14..61ed499500 100644
--- a/src/network/networkd-address.c
+++ b/src/network/networkd-address.c
@@ -1443,9 +1443,6 @@ int ipv4_dad_stop(Link *link) {
         assert(link);
 
         SET_FOREACH(address, link->addresses) {
-                if (!address->acd)
-                        continue;
-
                 k = sd_ipv4acd_stop(address->acd);
                 if (k < 0 && r >= 0)
                         r = k;
diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index 2920e615f3..24501c13da 100644
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -563,8 +563,7 @@ static int dhcp_lease_lost(Link *link) {
         link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
         link_dirty(link);
 
-        if (link->dhcp_acd)
-                (void) sd_ipv4acd_stop(link->dhcp_acd);
+        (void) sd_ipv4acd_stop(link->dhcp_acd);
 
         return r;
 }
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 928e883dcc..87ea5514b3 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -617,49 +617,39 @@ int link_stop_clients(Link *link, bool may_keep_dhcp) {
                          (link->manager->restarting ||
                           FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP_ON_STOP));
 
-        if (link->dhcp_client && !keep_dhcp) {
+        if (!keep_dhcp) {
                 k = sd_dhcp_client_stop(link->dhcp_client);
                 if (k < 0)
                         r = log_link_warning_errno(link, k, "Could not stop DHCPv4 client: %m");
         }
 
-        if (link->dhcp_acd) {
-                k = sd_ipv4acd_stop(link->dhcp_acd);
-                if (k < 0)
-                        r = log_link_warning_errno(link, k, "Could not stop IPv4 ACD client for DHCPv4: %m");
-        }
+        k = sd_ipv4acd_stop(link->dhcp_acd);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop IPv4 ACD client for DHCPv4: %m");
 
-        if (link->ipv4ll) {
-                k = sd_ipv4ll_stop(link->ipv4ll);
-                if (k < 0)
-                        r = log_link_warning_errno(link, k, "Could not stop IPv4 link-local: %m");
-        }
+        k = sd_ipv4ll_stop(link->ipv4ll);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop IPv4 link-local: %m");
 
         k = ipv4_dad_stop(link);
         if (k < 0)
                 r = log_link_warning_errno(link, k, "Could not stop IPv4 ACD client: %m");
 
-        if (link->dhcp6_client) {
-                k = sd_dhcp6_client_stop(link->dhcp6_client);
-                if (k < 0)
-                        r = log_link_warning_errno(link, k, "Could not stop DHCPv6 client: %m");
-        }
+        k = sd_dhcp6_client_stop(link->dhcp6_client);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop DHCPv6 client: %m");
 
         k = dhcp6_pd_remove(link);
         if (k < 0)
                 r = log_link_warning_errno(link, k, "Could not remove DHCPv6 PD addresses and routes: %m");
 
-        if (link->ndisc) {
-                k = sd_ndisc_stop(link->ndisc);
-                if (k < 0)
-                        r = log_link_warning_errno(link, k, "Could not stop IPv6 Router Discovery: %m");
-        }
+        k = sd_ndisc_stop(link->ndisc);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop IPv6 Router Discovery: %m");
 
-        if (link->radv) {
-                k = sd_radv_stop(link->radv);
-                if (k < 0)
-                        r = log_link_warning_errno(link, k, "Could not stop IPv6 Router Advertisement: %m");
-        }
+        k = sd_radv_stop(link->radv);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop IPv6 Router Advertisement: %m");
 
         link_lldp_emit_stop(link);
         return r;
@@ -2094,8 +2084,7 @@ static int link_reconfigure_internal(Link *link, sd_netlink_message *m, bool for
         if (r < 0)
                 return r;
 
-        if (link->dhcp_server)
-                (void) sd_dhcp_server_stop(link->dhcp_server);
+        (void) sd_dhcp_server_stop(link->dhcp_server);
 
         r = link_drop_config(link);
         if (r < 0)
@@ -2547,8 +2536,7 @@ static int link_carrier_lost(Link *link) {
                 return r;
         }
 
-        if (link->dhcp_server)
-                (void) sd_dhcp_server_stop(link->dhcp_server);
+        (void) sd_dhcp_server_stop(link->dhcp_server);
 
         r = link_drop_config(link);
         if (r < 0)

From c6a7531e0eb7930beee6103ca42640aa62f18f10 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 07:39:40 +0900
Subject: [PATCH 3/8] network: voidify sd_ipv4acd_stop() at one place

---
 src/network/networkd-address.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/network/networkd-address.c b/src/network/networkd-address.c
index 61ed499500..d006199ab0 100644
--- a/src/network/networkd-address.c
+++ b/src/network/networkd-address.c
@@ -1341,7 +1341,7 @@ static void static_address_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
                 assert_not_reached("Invalid IPv4ACD event.");
         }
 
-        sd_ipv4acd_stop(acd);
+        (void) sd_ipv4acd_stop(acd);
 
         return;
 }

From a391901eb2184413fa10a37f1635bf2092ac7b8e Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 07:39:55 +0900
Subject: [PATCH 4/8] network: drop unnecessary conditions

sd_ipv4acd_stop() and sd_ipv4ll_stop() are idempotent.
---
 src/network/networkd-address.c | 8 +++-----
 src/network/networkd-ipv4ll.c  | 8 +++-----
 src/network/networkd-radv.c    | 8 +++-----
 3 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/src/network/networkd-address.c b/src/network/networkd-address.c
index d006199ab0..0b269a1ba1 100644
--- a/src/network/networkd-address.c
+++ b/src/network/networkd-address.c
@@ -1402,11 +1402,9 @@ static int ipv4_dad_update_mac_one(Address *address) {
 
         running = sd_ipv4acd_is_running(address->acd);
 
-        if (running) {
-                r = sd_ipv4acd_stop(address->acd);
-                if (r < 0)
-                        return r;
-        }
+        r = sd_ipv4acd_stop(address->acd);
+        if (r < 0)
+                return r;
 
         r = sd_ipv4acd_set_mac(address->acd, &address->link->mac);
         if (r < 0)
diff --git a/src/network/networkd-ipv4ll.c b/src/network/networkd-ipv4ll.c
index 03f29e3b66..3be395e1ad 100644
--- a/src/network/networkd-ipv4ll.c
+++ b/src/network/networkd-ipv4ll.c
@@ -207,11 +207,9 @@ int ipv4ll_update_mac(Link *link) {
 
         restart = sd_ipv4ll_is_running(link->ipv4ll) > 0;
 
-        if (restart) {
-                r = sd_ipv4ll_stop(link->ipv4ll);
-                if (r < 0)
-                        return r;
-        }
+        r = sd_ipv4ll_stop(link->ipv4ll);
+        if (r < 0)
+                return r;
 
         r = sd_ipv4ll_set_mac(link->ipv4ll, &link->mac);
         if (r < 0)
diff --git a/src/network/networkd-radv.c b/src/network/networkd-radv.c
index 1167f2865f..bb80e91b6c 100644
--- a/src/network/networkd-radv.c
+++ b/src/network/networkd-radv.c
@@ -697,11 +697,9 @@ int radv_update_mac(Link *link) {
 
         restart = sd_radv_is_running(link->radv);
 
-        if (restart) {
-                r = sd_radv_stop(link->radv);
-                if (r < 0)
-                        return r;
-        }
+        r = sd_radv_stop(link->radv);
+        if (r < 0)
+                return r;
 
         r = sd_radv_set_mac(link->radv, &link->mac);
         if (r < 0)

From 2a99eed02c6bd5a7ca1ee0d75f6b39e7f6383e19 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 07:56:27 +0900
Subject: [PATCH 5/8] network: stop DHCPv4 server in link_stop_clients()

Then, rename link_stop_clients() -> link_stop_engines().
---
 src/network/networkd-link.c    | 16 ++++++++--------
 src/network/networkd-link.h    |  2 +-
 src/network/networkd-manager.c |  2 +-
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 87ea5514b3..d0cc3aafbd 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -605,7 +605,7 @@ static void link_enter_unmanaged(Link *link) {
         link_dirty(link);
 }
 
-int link_stop_clients(Link *link, bool may_keep_dhcp) {
+int link_stop_engines(Link *link, bool may_keep_dhcp) {
         int r = 0, k;
 
         assert(link);
@@ -627,6 +627,10 @@ int link_stop_clients(Link *link, bool may_keep_dhcp) {
         if (k < 0)
                 r = log_link_warning_errno(link, k, "Could not stop IPv4 ACD client for DHCPv4: %m");
 
+        k = sd_dhcp_server_stop(link->dhcp_server);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop DHCPv4 server: %m");
+
         k = sd_ipv4ll_stop(link->ipv4ll);
         if (k < 0)
                 r = log_link_warning_errno(link, k, "Could not stop IPv4 link-local: %m");
@@ -665,7 +669,7 @@ void link_enter_failed(Link *link) {
 
         link_set_state(link, LINK_STATE_FAILED);
 
-        (void) link_stop_clients(link, false);
+        (void) link_stop_engines(link, false);
 
         link_dirty(link);
 }
@@ -2080,12 +2084,10 @@ static int link_reconfigure_internal(Link *link, sd_netlink_message *m, bool for
         log_link_info(link, "Re-configuring with %s", network->filename);
 
         /* Dropping old .network file */
-        r = link_stop_clients(link, false);
+        r = link_stop_engines(link, false);
         if (r < 0)
                 return r;
 
-        (void) sd_dhcp_server_stop(link->dhcp_server);
-
         r = link_drop_config(link);
         if (r < 0)
                 return r;
@@ -2530,14 +2532,12 @@ static int link_carrier_lost(Link *link) {
         if (link->setting_mtu)
                 return 0;
 
-        r = link_stop_clients(link, false);
+        r = link_stop_engines(link, false);
         if (r < 0) {
                 link_enter_failed(link);
                 return r;
         }
 
-        (void) sd_dhcp_server_stop(link->dhcp_server);
-
         r = link_drop_config(link);
         if (r < 0)
                 return r;
diff --git a/src/network/networkd-link.h b/src/network/networkd-link.h
index 6e435796e5..a7ae2645f9 100644
--- a/src/network/networkd-link.h
+++ b/src/network/networkd-link.h
@@ -231,7 +231,7 @@ int link_set_mtu(Link *link, uint32_t mtu);
 
 bool link_ipv4ll_enabled(Link *link, AddressFamily mask);
 
-int link_stop_clients(Link *link, bool may_keep_dhcp);
+int link_stop_engines(Link *link, bool may_keep_dhcp);
 
 const char* link_state_to_string(LinkState s) _const_;
 LinkState link_state_from_string(const char *s) _pure_;
diff --git a/src/network/networkd-manager.c b/src/network/networkd-manager.c
index 2cd6830072..b5aba1f1dc 100644
--- a/src/network/networkd-manager.c
+++ b/src/network/networkd-manager.c
@@ -864,7 +864,7 @@ void manager_free(Manager *m) {
         free(m->state_file);
 
         HASHMAP_FOREACH(link, m->links)
-                (void) link_stop_clients(link, true);
+                (void) link_stop_engines(link, true);
 
         m->dhcp6_prefixes = hashmap_free_with_destructor(m->dhcp6_prefixes, dhcp6_pd_free);
         m->dhcp6_pd_prefixes = set_free_with_destructor(m->dhcp6_pd_prefixes, dhcp6_pd_free);

From 9cc65242d76d6f23bdf0a1d3ddc014a25abf57b0 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 07:57:33 +0900
Subject: [PATCH 6/8] network: also stop LLDP client in link_stop_engines()

---
 src/network/networkd-link.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index d0cc3aafbd..08b453f0e1 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -631,6 +631,10 @@ int link_stop_engines(Link *link, bool may_keep_dhcp) {
         if (k < 0)
                 r = log_link_warning_errno(link, k, "Could not stop DHCPv4 server: %m");
 
+        k = sd_lldp_stop(link->lldp);
+        if (k < 0)
+                r = log_link_warning_errno(link, k, "Could not stop LLDP: %m");
+
         k = sd_ipv4ll_stop(link->ipv4ll);
         if (k < 0)
                 r = log_link_warning_errno(link, k, "Could not stop IPv4 link-local: %m");

From 1c49487284645a2a318f7ab2a7f2606a2cc75d53 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 08:05:25 +0900
Subject: [PATCH 7/8] network: move link_lldp_emit_stop() to
 link_free_engines()

This should not change any behavior.
---
 src/network/networkd-link.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 08b453f0e1..324128be3c 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -493,8 +493,10 @@ static void link_free_engines(Link *link) {
         link->dhcp_server = sd_dhcp_server_unref(link->dhcp_server);
         link->dhcp_client = sd_dhcp_client_unref(link->dhcp_client);
         link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
+        link->dhcp_acd = sd_ipv4acd_unref(link->dhcp_acd);
 
         link->lldp = sd_lldp_unref(link->lldp);
+        link_lldp_emit_stop(link);
 
         ndisc_flush(link);
 
@@ -503,7 +505,6 @@ static void link_free_engines(Link *link) {
         link->dhcp6_lease = sd_dhcp6_lease_unref(link->dhcp6_lease);
         link->ndisc = sd_ndisc_unref(link->ndisc);
         link->radv = sd_radv_unref(link->radv);
-        link->dhcp_acd = sd_ipv4acd_unref(link->dhcp_acd);
 }
 
 static Link *link_free(Link *link) {
@@ -538,7 +539,6 @@ static Link *link_free(Link *link) {
         link->dhcp6_pd_addresses_old = set_free(link->dhcp6_pd_addresses_old);
         link->ndisc_addresses = set_free(link->ndisc_addresses);
 
-        link_lldp_emit_stop(link);
         link_free_engines(link);
         free(link->lease_file);
         free(link->lldp_file);

From 7abe175c007ce08be5f89d002b7e498c951f4537 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 15 Oct 2020 08:11:29 +0900
Subject: [PATCH 8/8] network: also unref IPv4 ACD clients in Address objects

This should not change any behavior, as currently link_free_engines() is
always called after all addresses are dropped. But the function may be
used in other places in the future. So, let's also stop the clients.
---
 src/network/networkd-address.c | 9 +++++++++
 src/network/networkd-address.h | 1 +
 src/network/networkd-link.c    | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/src/network/networkd-address.c b/src/network/networkd-address.c
index 0b269a1ba1..636812b556 100644
--- a/src/network/networkd-address.c
+++ b/src/network/networkd-address.c
@@ -1449,6 +1449,15 @@ int ipv4_dad_stop(Link *link) {
         return r;
 }
 
+void ipv4_dad_unref(Link *link) {
+        Address *address;
+
+        assert(link);
+
+        SET_FOREACH(address, link->addresses)
+                address->acd = sd_ipv4acd_unref(address->acd);
+}
+
 int config_parse_broadcast(
                 const char *unit,
                 const char *filename,
diff --git a/src/network/networkd-address.h b/src/network/networkd-address.h
index c0552979c5..0104747d9a 100644
--- a/src/network/networkd-address.h
+++ b/src/network/networkd-address.h
@@ -65,6 +65,7 @@ int link_drop_foreign_addresses(Link *link);
 int link_serialize_addresses(Link *link, FILE *f);
 int link_deserialize_addresses(Link *link, const char *addresses);
 
+void ipv4_dad_unref(Link *link);
 int ipv4_dad_stop(Link *link);
 int ipv4_dad_update_mac(Link *link);
 
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 324128be3c..4229e1f973 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -505,6 +505,8 @@ static void link_free_engines(Link *link) {
         link->dhcp6_lease = sd_dhcp6_lease_unref(link->dhcp6_lease);
         link->ndisc = sd_ndisc_unref(link->ndisc);
         link->radv = sd_radv_unref(link->radv);
+
+        ipv4_dad_unref(link);
 }
 
 static Link *link_free(Link *link) {