device: merge branch 'bg/parent-mtu-rh1723690-part1'

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/merge_requests/273

15 files changed, 165 insertions, 43 deletions

diff --git a/src/devices/nm-device-ethernet.c b/src/devices/nm-device-ethernet.c
index 83f2f61cf4..ddd5132690 100644
--- a/src/devices/nm-device-ethernet.c
+++ b/src/devices/nm-device-ethernet.c
@@ -1329,13 +1329,15 @@ act_stage3_ip_config_start (NMDevice *device,
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device,
+                    NMDeviceMtuSource *out_source,
+                    gboolean *out_force)
 {
 	/* MTU only set for plain ethernet */
 	if (NM_DEVICE_ETHERNET_GET_PRIVATE ((NMDeviceEthernet *) device)->ppp_manager)
 		return 0;
 
-	return nm_device_get_configured_mtu_for_wired (device, out_source);
+	return nm_device_get_configured_mtu_for_wired (device, out_source, out_force);
 }
 
 static void
diff --git a/src/devices/nm-device-infiniband.c b/src/devices/nm-device-infiniband.c
index d9b83b4284..24593ff1f5 100644
--- a/src/devices/nm-device-infiniband.c
+++ b/src/devices/nm-device-infiniband.c
@@ -97,7 +97,9 @@ act_stage1_prepare (NMDevice *device, NMDeviceStateReason *out_failure_reason)
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device,
+                    NMDeviceMtuSource *out_source,
+                    gboolean *out_force)
 {
 	return nm_device_get_configured_mtu_from_connection (device,
 	                                                     NM_TYPE_SETTING_INFINIBAND,
diff --git a/src/devices/nm-device-ip-tunnel.c b/src/devices/nm-device-ip-tunnel.c
index 34c35fc5b8..0becb5e568 100644
--- a/src/devices/nm-device-ip-tunnel.c
+++ b/src/devices/nm-device-ip-tunnel.c
@@ -840,7 +840,9 @@ create_and_realize (NMDevice *device,
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device,
+                    NMDeviceMtuSource *out_source,
+                    gboolean *out_force)
 {
 	return nm_device_get_configured_mtu_from_connection (device,
 	                                                     NM_TYPE_SETTING_IP_TUNNEL,
diff --git a/src/devices/nm-device-macsec.c b/src/devices/nm-device-macsec.c
index 17ee53c565..c9592a4971 100644
--- a/src/devices/nm-device-macsec.c
+++ b/src/devices/nm-device-macsec.c
@@ -52,6 +52,7 @@ NM_GOBJECT_PROPERTIES_DEFINE (NMDeviceMacsec,
 typedef struct {
 	NMPlatformLnkMacsec props;
 	gulong parent_state_id;
+	gulong parent_mtu_id;
 	Supplicant supplicant;
 	guint supplicant_timeout_id;
 	NMActRequestGetSecretsCallId *macsec_secrets_id;
@@ -100,6 +101,17 @@ parent_state_changed (NMDevice *parent,
 }
 
 static void
+parent_mtu_maybe_changed (NMDevice *parent,
+                          GParamSpec *pspec,
+                          gpointer user_data)
+{
+	/* the MTU of a MACsec device is limited by the parent's MTU.
+	 *
+	 * When the parent's MTU changes, try to re-set the MTU. */
+	nm_device_commit_mtu (user_data);
+}
+
+static void
 parent_changed_notify (NMDevice *device,
                        int old_ifindex,
                        NMDevice *old_parent,
@@ -119,12 +131,16 @@ parent_changed_notify (NMDevice *device,
 	 *  because NMDevice's dispose() will unset the parent, which in turn calls
 	 *  parent_changed_notify(). */
 	nm_clear_g_signal_handler (old_parent, &priv->parent_state_id);
+	nm_clear_g_signal_handler (old_parent, &priv->parent_mtu_id);
 
 	if (new_parent) {
 		priv->parent_state_id = g_signal_connect (new_parent,
 		                                          NM_DEVICE_STATE_CHANGED,
 		                                          G_CALLBACK (parent_state_changed),
 		                                          device);
+		priv->parent_mtu_id = g_signal_connect (new_parent, "notify::" NM_DEVICE_MTU,
+		                                        G_CALLBACK (parent_mtu_maybe_changed), device);
+
 
 		/* Set parent-dependent unmanaged flag */
 		nm_device_set_unmanaged_by_flags (device,
@@ -779,11 +795,15 @@ static void
 dispose (GObject *object)
 {
 	NMDeviceMacsec *self = NM_DEVICE_MACSEC (object);
+	NMDeviceMacsecPrivate *priv = NM_DEVICE_MACSEC_GET_PRIVATE (self);
 
 	macsec_secrets_cancel (self);
 	supplicant_interface_release (self);
 
 	G_OBJECT_CLASS (nm_device_macsec_parent_class)->dispose (object);
+
+	nm_assert (priv->parent_state_id == 0);
+	nm_assert (priv->parent_mtu_id == 0);
 }
 
 static const NMDBusInterfaceInfoExtended interface_info_device_macsec = {
@@ -826,6 +846,7 @@ nm_device_macsec_class_init (NMDeviceMacsecClass *klass)
 	device_class->connection_type_supported = NM_SETTING_MACSEC_SETTING_NAME;
 	device_class->connection_type_check_compatible = NM_SETTING_MACSEC_SETTING_NAME;
 	device_class->link_types = NM_DEVICE_DEFINE_LINK_TYPES (NM_LINK_TYPE_MACSEC);
+	device_class->mtu_parent_delta = 32;
 
 	device_class->act_stage2_config = act_stage2_config;
 	device_class->create_and_realize = create_and_realize;
@@ -835,7 +856,7 @@ nm_device_macsec_class_init (NMDeviceMacsecClass *klass)
 	device_class->is_available = is_available;
 	device_class->parent_changed_notify = parent_changed_notify;
 	device_class->state_changed = device_state_changed;
-	device_class->get_configured_mtu = nm_device_get_configured_mtu_for_wired;
+	device_class->get_configured_mtu = nm_device_get_configured_mtu_wired_parent;
 
 	obj_properties[PROP_SCI] =
 	    g_param_spec_uint64 (NM_DEVICE_MACSEC_SCI, "", "",
diff --git a/src/devices/nm-device-macvlan.c b/src/devices/nm-device-macvlan.c
index f27211f5f5..3633f02d46 100644
--- a/src/devices/nm-device-macvlan.c
+++ b/src/devices/nm-device-macvlan.c
@@ -34,6 +34,7 @@ NM_GOBJECT_PROPERTIES_DEFINE (NMDeviceMacvlan,
 
 typedef struct {
 	gulong parent_state_id;
+	gulong parent_mtu_id;
 	NMPlatformLnkMacvlan props;
 } NMDeviceMacvlanPrivate;
 
@@ -121,6 +122,17 @@ parent_state_changed (NMDevice *parent,
 }
 
 static void
+parent_mtu_maybe_changed (NMDevice *parent,
+                          GParamSpec *pspec,
+                          gpointer user_data)
+{
+	/* the MTU of a macvlan/macvtap device is limited by the parent's MTU.
+	 *
+	 * When the parent's MTU changes, try to re-set the MTU. */
+	nm_device_commit_mtu (user_data);
+}
+
+static void
 parent_changed_notify (NMDevice *device,
                        int old_ifindex,
                        NMDevice *old_parent,
@@ -136,12 +148,15 @@ parent_changed_notify (NMDevice *device,
 	 *  because NMDevice's dispose() will unset the parent, which in turn calls
 	 *  parent_changed_notify(). */
 	nm_clear_g_signal_handler (old_parent, &priv->parent_state_id);
+	nm_clear_g_signal_handler (old_parent, &priv->parent_mtu_id);
 
 	if (new_parent) {
 		priv->parent_state_id = g_signal_connect (new_parent,
 		                                          NM_DEVICE_STATE_CHANGED,
 		                                          G_CALLBACK (parent_state_changed),
 		                                          device);
+		priv->parent_mtu_id = g_signal_connect (new_parent, "notify::" NM_DEVICE_MTU,
+		                                        G_CALLBACK (parent_mtu_maybe_changed), device);
 
 		/* Set parent-dependent unmanaged flag */
 		nm_device_set_unmanaged_by_flags (device,
@@ -447,6 +462,17 @@ nm_device_macvlan_init (NMDeviceMacvlan *self)
 {
 }
 
+static void
+dispose (GObject *object)
+{
+	NMDeviceMacvlanPrivate *priv = NM_DEVICE_MACVLAN_GET_PRIVATE (object);
+
+	G_OBJECT_CLASS (nm_device_macvlan_parent_class)->dispose (object);
+
+	nm_assert (priv->parent_state_id == 0);
+	nm_assert (priv->parent_mtu_id == 0);
+}
+
 static const NMDBusInterfaceInfoExtended interface_info_device_macvlan = {
 	.parent = NM_DEFINE_GDBUS_INTERFACE_INFO_INIT (
 		NM_DBUS_INTERFACE_DEVICE_MACVLAN,
@@ -470,6 +496,7 @@ nm_device_macvlan_class_init (NMDeviceMacvlanClass *klass)
 	NMDBusObjectClass *dbus_object_class = NM_DBUS_OBJECT_CLASS (klass);
 	NMDeviceClass *device_class = NM_DEVICE_CLASS (klass);
 
+	object_class->dispose = dispose;
 	object_class->get_property = get_property;
 	object_class->set_property = set_property;
 
@@ -478,13 +505,14 @@ nm_device_macvlan_class_init (NMDeviceMacvlanClass *klass)
 	device_class->connection_type_supported = NM_SETTING_MACVLAN_SETTING_NAME;
 	device_class->connection_type_check_compatible = NM_SETTING_MACVLAN_SETTING_NAME;
 	device_class->link_types = NM_DEVICE_DEFINE_LINK_TYPES (NM_LINK_TYPE_MACVLAN, NM_LINK_TYPE_MACVTAP);
+	device_class->mtu_parent_delta = 0;
 
 	device_class->act_stage1_prepare_set_hwaddr_ethernet = TRUE;
 	device_class->check_connection_compatible = check_connection_compatible;
 	device_class->complete_connection = complete_connection;
 	device_class->create_and_realize = create_and_realize;
 	device_class->get_generic_capabilities = get_generic_capabilities;
-	device_class->get_configured_mtu = nm_device_get_configured_mtu_for_wired;
+	device_class->get_configured_mtu = nm_device_get_configured_mtu_wired_parent;
 	device_class->is_available = is_available;
 	device_class->link_changed = link_changed;
 	device_class->parent_changed_notify = parent_changed_notify;
diff --git a/src/devices/nm-device-private.h b/src/devices/nm-device-private.h
index 4c38fa7a2a..e87733ef3f 100644
--- a/src/devices/nm-device-private.h
+++ b/src/devices/nm-device-private.h
@@ -166,7 +166,11 @@ guint32 nm_device_get_configured_mtu_from_connection (NMDevice *device,
                                                       GType setting_type,
                                                       NMDeviceMtuSource *out_source);
 
-guint32 nm_device_get_configured_mtu_for_wired (NMDevice *self, NMDeviceMtuSource *out_source);
+guint32 nm_device_get_configured_mtu_for_wired (NMDevice *self, NMDeviceMtuSource *out_source, gboolean *out_force);
+
+guint32 nm_device_get_configured_mtu_wired_parent (NMDevice *self,
+                                                   NMDeviceMtuSource *out_source,
+                                                   gboolean *out_force);
 
 void nm_device_commit_mtu (NMDevice *self);
 
diff --git a/src/devices/nm-device-vlan.c b/src/devices/nm-device-vlan.c
index 02262b21d6..b6efeb81a5 100644
--- a/src/devices/nm-device-vlan.c
+++ b/src/devices/nm-device-vlan.c
@@ -502,26 +502,6 @@ act_stage1_prepare (NMDevice *device, NMDeviceStateReason *out_failure_reason)
 	return NM_ACT_STAGE_RETURN_SUCCESS;
 }
 
-static guint32
-get_configured_mtu (NMDevice *self, NMDeviceMtuSource *out_source)
-{
-	guint32 mtu = 0;
-	int ifindex;
-
-	mtu = nm_device_get_configured_mtu_for_wired (self, out_source);
-	if (*out_source != NM_DEVICE_MTU_SOURCE_NONE)
-		return mtu;
-
-	/* Inherit the MTU from parent device, if any */
-	ifindex = nm_device_parent_get_ifindex (self);
-	if (ifindex > 0) {
-		mtu = nm_platform_link_get_mtu (nm_device_get_platform (NM_DEVICE (self)), ifindex);
-		*out_source = NM_DEVICE_MTU_SOURCE_PARENT;
-	}
-
-	return mtu;
-}
-
 /*****************************************************************************/
 
 static void
@@ -577,6 +557,7 @@ nm_device_vlan_class_init (NMDeviceVlanClass *klass)
 	device_class->connection_type_supported = NM_SETTING_VLAN_SETTING_NAME;
 	device_class->connection_type_check_compatible = NM_SETTING_VLAN_SETTING_NAME;
 	device_class->link_types = NM_DEVICE_DEFINE_LINK_TYPES (NM_LINK_TYPE_VLAN);
+	device_class->mtu_parent_delta = 0; /* VLANs can have the same MTU of parent */
 
 	device_class->create_and_realize = create_and_realize;
 	device_class->link_changed = link_changed;
@@ -584,7 +565,7 @@ nm_device_vlan_class_init (NMDeviceVlanClass *klass)
 	device_class->get_generic_capabilities = get_generic_capabilities;
 	device_class->act_stage1_prepare_set_hwaddr_ethernet = TRUE;
 	device_class->act_stage1_prepare = act_stage1_prepare;
-	device_class->get_configured_mtu = get_configured_mtu;
+	device_class->get_configured_mtu = nm_device_get_configured_mtu_wired_parent;
 	device_class->is_available = is_available;
 	device_class->parent_changed_notify = parent_changed_notify;
 
diff --git a/src/devices/nm-device-wireguard.c b/src/devices/nm-device-wireguard.c
index c769a86be3..d65607089b 100644
--- a/src/devices/nm-device-wireguard.c
+++ b/src/devices/nm-device-wireguard.c
@@ -1691,7 +1691,7 @@ act_stage3_ip_config_start (NMDevice *device,
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source, gboolean *out_force)
 {
 	/* When "MTU" for `wg-quick up` is unset, it calls `ip route get` for
 	 * each configured endpoint, to determine the suitable MTU how to reach
diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index 1fe74b55e3..57de04d4db 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -9317,13 +9317,59 @@ nm_device_get_configured_mtu_from_connection (NMDevice *self,
 }
 
 guint32
-nm_device_get_configured_mtu_for_wired (NMDevice *self, NMDeviceMtuSource *out_source)
+nm_device_get_configured_mtu_for_wired (NMDevice *self,
+                                        NMDeviceMtuSource *out_source,
+                                        gboolean *out_force)
 {
 	return nm_device_get_configured_mtu_from_connection (self,
 	                                                     NM_TYPE_SETTING_WIRED,
 	                                                     out_source);
 }
 
+guint32
+nm_device_get_configured_mtu_wired_parent (NMDevice *self,
+                                           NMDeviceMtuSource *out_source,
+                                           gboolean *out_force)
+{
+	guint32 mtu = 0;
+	guint32 parent_mtu = 0;
+	int ifindex;
+
+	ifindex = nm_device_parent_get_ifindex (self);
+	if (ifindex > 0) {
+		parent_mtu = nm_platform_link_get_mtu (nm_device_get_platform (self), ifindex);
+		if (parent_mtu >= NM_DEVICE_GET_CLASS (self)->mtu_parent_delta)
+			parent_mtu -= NM_DEVICE_GET_CLASS (self)->mtu_parent_delta;
+		else
+			parent_mtu = 0;
+	}
+
+	mtu = nm_device_get_configured_mtu_for_wired (self, out_source, NULL);
+
+	if (parent_mtu && mtu > parent_mtu) {
+		/* Trying to set a MTU that is out of range from configuration:
+		 * fall back to the parent MTU and set force flag so that it
+		 * overrides an MTU with higher priority already configured.
+		 */
+		 *out_source = NM_DEVICE_MTU_SOURCE_PARENT;
+		 *out_force = TRUE;
+		 return parent_mtu;
+	}
+
+	if (*out_source != NM_DEVICE_MTU_SOURCE_NONE) {
+		nm_assert (mtu > 0);
+		return mtu;
+	}
+
+	/* Inherit the MTU from parent device, if any */
+	if (parent_mtu) {
+		mtu = parent_mtu;
+		*out_source = NM_DEVICE_MTU_SOURCE_PARENT;
+	}
+
+	return mtu;
+}
+
 /*****************************************************************************/
 
 static void
@@ -9375,15 +9421,34 @@ _commit_mtu (NMDevice *self, const NMIP4Config *config)
 
 	{
 		guint32 mtu = 0;
+		gboolean force = FALSE;
 
-		/* preferably, get the MTU from explicit user-configuration.
-		 * Only if that fails, look at the current @config (which contains
-		 * MTUs from DHCP/PPP) or maybe fallback to a device-specific MTU. */
+		/* We take the MTU from various sources: (in order of increasing
+		 * priority) parent link, IP configuration (which contains the
+		 * MTU from DHCP/PPP), connection profile.
+		 *
+		 * We could just compare it with the platform MTU and apply it
+		 * when different, but this would revert at random times manual
+		 * changes done by the user with the MTU from the connection.
+		 *
+		 * Instead, we remember the source of the currently configured
+		 * MTU and apply the new one only when the new source has a
+		 * higher priority, so that we don't set a MTU from same source
+		 * multiple times. An exception to this is for the PARENT
+		 * source, since we need to keep tracking the parent MTU when it
+		 * changes.
+		 *
+		 * The subclass can set the @force argument to TRUE to signal that the
+		 * returned MTU should be applied even if it has a lower priority. This
+		 * is useful when the value from a lower source should
+		 * preempt the one from higher ones.
+		 */
 
 		if (NM_DEVICE_GET_CLASS (self)->get_configured_mtu)
-			mtu = NM_DEVICE_GET_CLASS (self)->get_configured_mtu (self, &source);
+			mtu = NM_DEVICE_GET_CLASS (self)->get_configured_mtu (self, &source, &force);
 
 		if (   config
+		    && !force
 		    && source < NM_DEVICE_MTU_SOURCE_IP_CONFIG
 		    && nm_ip4_config_get_mtu (config)) {
 			mtu = nm_ip4_config_get_mtu (config);
@@ -9392,14 +9457,16 @@ _commit_mtu (NMDevice *self, const NMIP4Config *config)
 
 		if (mtu != 0) {
 			_LOGT (LOGD_DEVICE,
-			       "mtu: value %u from source '%s' (%u), current source '%s' (%u)",
+			       "mtu: value %u from source '%s' (%u), current source '%s' (%u)%s",
 			       (guint) mtu,
 			       mtu_source_to_str (source), (guint) source,
-			       mtu_source_to_str (priv->mtu_source), (guint) priv->mtu_source);
+			       mtu_source_to_str (priv->mtu_source), (guint) priv->mtu_source,
+			       force ? " (forced)" : "");
 		}
 
 		if (   mtu != 0
-		    && (   source > priv->mtu_source
+		    && (   force
+		        || source > priv->mtu_source
 		        || (priv->mtu_source == NM_DEVICE_MTU_SOURCE_PARENT && source == priv->mtu_source)))
 			mtu_desired = mtu;
 		else {
@@ -14845,6 +14912,7 @@ nm_device_cleanup (NMDevice *self, NMDeviceStateReason reason, CleanupType clean
 	}
 
 	priv->mtu_source = NM_DEVICE_MTU_SOURCE_NONE;
+	priv->ip6_mtu = 0;
 	if (priv->mtu_initial || priv->ip6_mtu_initial) {
 		ifindex = nm_device_get_ip_ifindex (self);
 
diff --git a/src/devices/nm-device.h b/src/devices/nm-device.h
index df8777b720..aa2de5a4de 100644
--- a/src/devices/nm-device.h
+++ b/src/devices/nm-device.h
@@ -225,6 +225,10 @@ typedef struct _NMDeviceClass {
 
 	const NMLinkType *link_types;
 
+	/* if the device MTU is set based on parent's one, this specifies
+	 * a delta in the MTU allowed value due the encapsulation overhead */
+	guint16 mtu_parent_delta;
+
 	/* Whether the device type is a master-type. This depends purely on the
 	 * type (NMDeviceClass), not the actual device instance. */
 	bool is_master:1;
@@ -321,7 +325,9 @@ typedef struct _NMDeviceClass {
 	                                  NMSettingsConnection *sett_conn,
 	                                  char **specific_object);
 
-	guint32     (*get_configured_mtu) (NMDevice *self, NMDeviceMtuSource *out_source);
+	guint32     (*get_configured_mtu) (NMDevice *self,
+	                                   NMDeviceMtuSource *out_source,
+	                                   gboolean *out_force);
 
 	/* allow the subclass to overwrite the routing table. This is mainly useful
 	 * to change from partial mode (route-table=0) to full-sync mode (route-table=254). */
diff --git a/src/devices/wifi/nm-device-iwd.c b/src/devices/wifi/nm-device-iwd.c
index 8e3aafda12..6b587e3f3b 100644
--- a/src/devices/wifi/nm-device-iwd.c
+++ b/src/devices/wifi/nm-device-iwd.c
@@ -1865,7 +1865,9 @@ out:
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device,
+                    NMDeviceMtuSource *out_source,
+                    gboolean *out_force)
 {
 	return nm_device_get_configured_mtu_from_connection (device,
 	                                                     NM_TYPE_SETTING_WIRELESS,
diff --git a/src/devices/wifi/nm-device-wifi-p2p.c b/src/devices/wifi/nm-device-wifi-p2p.c
index cd672f89da..34ff70fa0e 100644
--- a/src/devices/wifi/nm-device-wifi-p2p.c
+++ b/src/devices/wifi/nm-device-wifi-p2p.c
@@ -604,7 +604,9 @@ deactivate (NMDevice *device)
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device,
+                    NMDeviceMtuSource *out_source,
+                    gboolean *out_force)
 {
 	*out_source = NM_DEVICE_MTU_SOURCE_NONE;
 	return 0;
diff --git a/src/devices/wifi/nm-device-wifi.c b/src/devices/wifi/nm-device-wifi.c
index 04c90058a1..1d49ea4344 100644
--- a/src/devices/wifi/nm-device-wifi.c
+++ b/src/devices/wifi/nm-device-wifi.c
@@ -2895,7 +2895,9 @@ act_stage3_ip_config_start (NMDevice *device,
 }
 
 static guint32
-get_configured_mtu (NMDevice *device, NMDeviceMtuSource *out_source)
+get_configured_mtu (NMDevice *device,
+                    NMDeviceMtuSource *out_source,
+                    gboolean *out_force)
 {
 	return nm_device_get_configured_mtu_from_connection (device,
 	                                                     NM_TYPE_SETTING_WIRELESS,
diff --git a/src/devices/wwan/nm-modem.c b/src/devices/wwan/nm-modem.c
index e49cffcfaf..ad6449b17e 100644
--- a/src/devices/wwan/nm-modem.c
+++ b/src/devices/wwan/nm-modem.c
@@ -910,7 +910,9 @@ nm_modem_stage3_ip6_config_start (NMModem *self,
 }
 
 guint32
-nm_modem_get_configured_mtu (NMDevice *self, NMDeviceMtuSource *out_source)
+nm_modem_get_configured_mtu (NMDevice *self,
+                             NMDeviceMtuSource *out_source,
+                             gboolean *out_force)
 {
 	NMConnection *connection;
 	NMSetting *setting;
diff --git a/src/devices/wwan/nm-modem.h b/src/devices/wwan/nm-modem.h
index c83ca538b9..f2de990b80 100644
--- a/src/devices/wwan/nm-modem.h
+++ b/src/devices/wwan/nm-modem.h
@@ -275,7 +275,7 @@ void nm_modem_emit_ip6_config_result (NMModem *self,
 
 const char *nm_modem_ip_type_to_string (NMModemIPType ip_type);
 
-guint32 nm_modem_get_configured_mtu (NMDevice *self, NMDeviceMtuSource *out_source);
+guint32 nm_modem_get_configured_mtu (NMDevice *self, NMDeviceMtuSource *out_source, gboolean *out_force);
 
 void _nm_modem_set_operator_code (NMModem *self, const char *operator_code);
 void _nm_modem_set_apn           (NMModem *self, const char *apn);