Merge pull request #14558 from FRRouting/mergify/bp/stable/9.0/pr-13617

pimd: Fix missing pimreg interface (backport #13617)

pimd/pim_iface.c

@@ -1490,9 +1490,16 @@ void pim_if_create_pimreg(struct pim_instance *pim)
 					       pim->vrf->name);
 		pim->regiface->ifindex = PIM_OIF_PIM_REGISTER_VIF;
 
-		if (!pim->regiface->info)
-			pim_if_new(pim->regiface, false, false, true,
-				   false /*vxlan_term*/);
+		/*
+		 * The pimreg interface might has been removed from
+		 * kerenl with the VRF's deletion.  It must be
+		 * recreated, so delete the old one first.
+		 */
+		if (pim->regiface->info)
+			pim_if_delete(pim->regiface);
+
+		pim_if_new(pim->regiface, false, false, true,
+			   false /*vxlan_term*/);
 
 		/*
 		 * On vrf moves we delete the interface if there