bond: avoid setting "active_slave" option without interface enslaved

Kernel will reject setting "active_slave", if the interface is not enslaved or not
up. We already handle that by setting the option whenever we enslave an interface.
However, we also must not set it initially, otherwise we get an ugly error log message:

    NetworkManager[939]: <debug> [1594709143.7459] platform-linux: sysctl: setting net:/sys/class/net/bond99/bonding/active_slave to eth1 (current value is )
    NetworkManager[939]: <error> [1594709143.7459] platform-linux: sysctl: failed to set bonding/active_slave to eth1: (22) Invalid argument
    NetworkManager[939]: <warn>  [1594709143.7460] device (bond99): failed to set bonding attribute active_slave to eth1
    ...
    kernel: bond99: (slave eth1): Device is not bonding slave
    kernel: bond99: option active_slave: invalid value (eth1)

See-also: https://bugzilla.redhat.com/show_bug.cgi?id=1856640

src/devices/nm-device-bond.c

@@ -8,6 +8,7 @@
 #include "nm-device-bond.h"
 
 #include <stdlib.h>
+#include <net/if.h>
 
 #include "NetworkManagerUtils.h"
 #include "nm-device-private.h"
@@ -261,6 +262,40 @@ set_bond_attr_or_default (NMDevice *device,
 	_set_bond_attr (device, opt, value);
 }
 
+static void
+set_bond_attr_active_slave (NMDevice *device, NMSettingBond *s_bond)
+{
+	NMDeviceBond *self = NM_DEVICE_BOND (device);
+	const NMPlatformLink *plink;
+	const char *value;
+	const char *error_reason;
+	int ifindex;
+
+	value = nm_setting_bond_get_option_or_default (s_bond, NM_SETTING_BOND_OPTION_ACTIVE_SLAVE);
+	if (!value)
+		return;
+
+	if (!nm_str_is_empty (value)) {
+		ifindex = nm_device_get_ifindex (device);
+		plink = nm_platform_link_get_by_ifname (nm_device_get_platform (device), value);
+		if (!plink)
+			error_reason = "does not exist";
+		else if (plink->master != ifindex)
+			error_reason = "is not yet enslaved";
+		else if (!NM_FLAGS_HAS (plink->n_ifi_flags, IFF_UP))
+			error_reason = "is not up";
+		else
+			error_reason = NULL;
+
+		if (error_reason) {
+			_LOGT (LOGD_BOND, "bond option 'active_slave' not set as device \"%s\" %s", value, error_reason);
+			return;
+		}
+	}
+
+	_set_bond_attr (device, NM_SETTING_BOND_OPTION_ACTIVE_SLAVE, value);
+}
+
 static gboolean
 apply_bonding_config (NMDeviceBond *self)
 {
@@ -300,7 +335,7 @@ apply_bonding_config (NMDeviceBond *self)
 	                 nm_setting_bond_get_option_or_default (s_bond, NM_SETTING_BOND_OPTION_ARP_IP_TARGET));
 
 	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_AD_ACTOR_SYSTEM);
-	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_ACTIVE_SLAVE);
+	set_bond_attr_active_slave (device, s_bond);
 	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_AD_ACTOR_SYS_PRIO);
 	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_AD_SELECT);
 	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_AD_USER_PORT_KEY);
@@ -378,7 +413,7 @@ enslave_slave (NMDevice *device,
 				if (nm_streq0 (active, nm_device_get_iface (slave))) {
 					nm_platform_sysctl_master_set_option (nm_device_get_platform (device),
 					                                      nm_device_get_ifindex (device),
-					                                      "active_slave",
+					                                      NM_SETTING_BOND_OPTION_ACTIVE_SLAVE,
 					                                      active);
 					_LOGD (LOGD_BOND, "setting slave %s as active one for master %s",
 					       active, nm_device_get_iface (device));
@@ -577,10 +612,8 @@ reapply_connection (NMDevice *device, NMConnection *con_old, NMConnection *con_n
 	mode = _nm_setting_bond_mode_from_string (value);
 	g_return_if_fail (mode != NM_BOND_MODE_UNKNOWN);
 
-	/* Primary */
 	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_PRIMARY);
-	/* Active slave */
-	set_bond_attr_or_default (device, s_bond, NM_SETTING_BOND_OPTION_ACTIVE_SLAVE);
+	set_bond_attr_active_slave (device, s_bond);
 }
 
 /*****************************************************************************/

[NetworkManagerCI]

https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/1662/

Result: UNSTABLE: Some tests failing

Passed: 1067, Failed: 3

vrf_one_address_two_devices vrf_restart_persistence ovs_cloned_mac_set_on_iface