netstack: remove error return value from function that never errors

pkg/tcpip/stack/nic.go

@@ -928,7 +928,7 @@ func (n *nic) setNUDConfigs(protocol tcpip.NetworkProtocolNumber, c NUDConfigura
 	return &tcpip.ErrNotSupported{}
 }
 
-func (n *nic) registerPacketEndpoint(netProto tcpip.NetworkProtocolNumber, ep PacketEndpoint) tcpip.Error {
+func (n *nic) registerPacketEndpoint(netProto tcpip.NetworkProtocolNumber, ep PacketEndpoint) {
 	n.packetEPsMu.Lock()
 	defer n.packetEPsMu.Unlock()
 
@@ -938,8 +938,6 @@ func (n *nic) registerPacketEndpoint(netProto tcpip.NetworkProtocolNumber, ep Pa
 		n.packetEPs[netProto] = eps
 	}
 	eps.add(ep)
-
-	return nil
 }
 
 func (n *nic) unregisterPacketEndpoint(netProto tcpip.NetworkProtocolNumber, ep PacketEndpoint) {

pkg/tcpip/stack/stack.go

@@ -1840,10 +1840,7 @@ func (s *Stack) RegisterPacketEndpoint(nicID tcpip.NICID, netProto tcpip.Network
 	if nicID == 0 {
 		// Register with each NIC.
 		for _, nic := range s.nics {
-			if err := nic.registerPacketEndpoint(netProto, ep); err != nil {
-				s.unregisterPacketEndpointLocked(0, netProto, ep)
-				return err
-			}
+			nic.registerPacketEndpoint(netProto, ep)
 		}
 		return nil
 	}
@@ -1853,9 +1850,7 @@ func (s *Stack) RegisterPacketEndpoint(nicID tcpip.NICID, netProto tcpip.Network
 	if !ok {
 		return &tcpip.ErrUnknownNICID{}
 	}
-	if err := nic.registerPacketEndpoint(netProto, ep); err != nil {
-		return err
-	}
+	nic.registerPacketEndpoint(netProto, ep)
 
 	return nil
 }

pkg/tcpip/transport/packet/endpoint.go

@@ -94,7 +94,7 @@ type endpoint struct {
 }
 
 // NewEndpoint returns a new packet endpoint.
-func NewEndpoint(s *stack.Stack, cooked bool, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, tcpip.Error) {
+func NewEndpoint(s *stack.Stack, cooked bool, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) tcpip.Endpoint {
 	ep := &endpoint{
 		stack:         s,
 		cooked:        cooked,
@@ -115,10 +115,9 @@ func NewEndpoint(s *stack.Stack, cooked bool, netProto tcpip.NetworkProtocolNumb
 		ep.ops.SetReceiveBufferSize(int64(rs.Default), false /* notify */)
 	}
 
-	if err := s.RegisterPacketEndpoint(0, netProto, ep); err != nil {
-		return nil, err
-	}
-	return ep, nil
+	s.RegisterPacketEndpoint(0, netProto, ep)
+
+	return ep
 }
 
 // Abort implements stack.TransportEndpoint.Abort.

pkg/tcpip/transport/raw/protocol.go

@@ -32,7 +32,7 @@ func (EndpointFactory) NewUnassociatedEndpoint(stack *stack.Stack, netProto tcpi
 
 // NewPacketEndpoint implements stack.RawFactory.NewPacketEndpoint.
 func (EndpointFactory) NewPacketEndpoint(stack *stack.Stack, cooked bool, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, tcpip.Error) {
-	return packet.NewEndpoint(stack, cooked, netProto, waiterQueue)
+	return packet.NewEndpoint(stack, cooked, netProto, waiterQueue), nil
 }
 
 // CreateOnlyFactory implements stack.RawFactory. It allows creation of raw