bgpd: release manual vpn label on instance deletion

When a BGP instance with a manually assigned VPN label is deleted, the
label is not released from the Zebra label registry. As a result,
reapplying a configuration with the same manual label leads to VPN
prefix export failures.

For example, with the following configuration:

> router bgp 65000 vrf BLUE
>  address-family ipv4 unicast
>   label vpn export <int>

Release zebra label registry on unconfiguration.

Fixes: d162d5f ("bgpd: fix hardset l3vpn label available in mpls pool")
Signed-off-by: Louis Scalbert <[email protected]>
(cherry picked from commit d636362)

# Conflicts:
#	bgpd/bgpd.c

bgpd/bgpd.c

@@ -4046,6 +4046,37 @@ int bgp_delete(struct bgp *bgp)
 
 	bgp_vpn_leak_unimport(bgp);
 
+<<<<<<< HEAD
+=======
+	/*
+	 * Release SRv6 SIDs, like it's done in `vpn_leak_postchange()`
+	 * and bgp_sid_vpn_export_cmd/af_sid_vpn_export_cmd commands.
+	 */
+	bgp->tovpn_sid_index = 0;
+	UNSET_FLAG(bgp->vrf_flags, BGP_VRF_TOVPN_SID_AUTO);
+	delete_vrf_tovpn_sid_per_vrf(bgp_default, bgp);
+	for (afi = AFI_IP; afi < AFI_MAX; afi++) {
+		bgp->vpn_policy[afi].tovpn_sid_index = 0;
+		UNSET_FLAG(bgp->vpn_policy[afi].flags, BGP_VPN_POLICY_TOVPN_SID_AUTO);
+		delete_vrf_tovpn_sid_per_af(bgp_default, bgp, afi);
+
+		vpn_leak_zebra_vrf_sid_withdraw(bgp, afi);
+	}
+
+	/* release auto vpn labels */
+	bgp_vpn_release_label(bgp, AFI_IP, true);
+	bgp_vpn_release_label(bgp, AFI_IP6, true);
+
+	/* release manual vpn labels */
+	for (afi = AFI_IP; afi < AFI_MAX; afi++) {
+		if (!CHECK_FLAG(bgp->vpn_policy[afi].flags, BGP_VPN_POLICY_TOVPN_LABEL_MANUAL_REG))
+			continue;
+		bgp_zebra_release_label_range(bgp->vpn_policy[afi].tovpn_label,
+					      bgp->vpn_policy[afi].tovpn_label);
+		UNSET_FLAG(bgp->vpn_policy[afi].flags, BGP_VPN_POLICY_TOVPN_LABEL_MANUAL_REG);
+	}
+
+>>>>>>> d6363625c (bgpd: release manual vpn label on instance deletion)
 	hook_call(bgp_inst_delete, bgp);
 
 	FOREACH_AFI_SAFI (afi, safi)