Avoid locking when route doesn't require resolution
When a route does not need to resolve a remote link address to send a packet, avoid having to obtain the pending packets queue's lock. PiperOrigin-RevId: 354456280
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@ -309,7 +309,26 @@ func (n *NIC) WritePacket(r *Route, gso *GSO, protocol tcpip.NetworkProtocolNumb
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return err
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}
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func (n *NIC) writePacketBuffer(r RouteInfo, gso *GSO, protocol tcpip.NetworkProtocolNumber, pkt pendingPacketBuffer) (int, tcpip.Error) {
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switch pkt := pkt.(type) {
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case *PacketBuffer:
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if err := n.writePacket(r, gso, protocol, pkt); err != nil {
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return 0, err
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}
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return 1, nil
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case *PacketBufferList:
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return n.writePackets(r, gso, protocol, *pkt)
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default:
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panic(fmt.Sprintf("unrecognized pending packet buffer type = %T", pkt))
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}
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}
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func (n *NIC) enqueuePacketBuffer(r *Route, gso *GSO, protocol tcpip.NetworkProtocolNumber, pkt pendingPacketBuffer) (int, tcpip.Error) {
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routeInfo, _, err := r.resolvedFields(nil)
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switch err.(type) {
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case nil:
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return n.writePacketBuffer(routeInfo, gso, protocol, pkt)
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case *tcpip.ErrWouldBlock:
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// As per relevant RFCs, we should queue packets while we wait for link
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// resolution to complete.
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//
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@ -322,12 +341,15 @@ func (n *NIC) enqueuePacketBuffer(r *Route, gso *GSO, protocol tcpip.NetworkProt
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// RFC 4861 section 7.2.2 (for IPv6):
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// While waiting for address resolution to complete, the sender MUST, for
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// each neighbor, retain a small queue of packets waiting for address
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// resolution to complete. The queue MUST hold at least one packet, and MAY
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// contain more. However, the number of queued packets per neighbor SHOULD
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// be limited to some small value. When a queue overflows, the new arrival
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// SHOULD replace the oldest entry. Once address resolution completes, the
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// node transmits any queued packets.
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// resolution to complete. The queue MUST hold at least one packet, and
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// MAY contain more. However, the number of queued packets per neighbor
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// SHOULD be limited to some small value. When a queue overflows, the new
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// arrival SHOULD replace the oldest entry. Once address resolution
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// completes, the node transmits any queued packets.
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return n.linkResQueue.enqueue(r, gso, protocol, pkt)
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default:
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return 0, err
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}
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}
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// WritePacketToRemote implements NetworkInterface.
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@ -114,20 +114,6 @@ func (f *packetsPendingLinkResolution) dequeue(ch <-chan struct{}, linkAddr tcpi
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}
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}
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func (f *packetsPendingLinkResolution) writePacketBuffer(r RouteInfo, gso *GSO, proto tcpip.NetworkProtocolNumber, pkt pendingPacketBuffer) (int, tcpip.Error) {
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switch pkt := pkt.(type) {
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case *PacketBuffer:
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if err := f.nic.writePacket(r, gso, proto, pkt); err != nil {
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return 0, err
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}
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return 1, nil
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case *PacketBufferList:
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return f.nic.writePackets(r, gso, proto, *pkt)
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default:
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panic(fmt.Sprintf("unrecognized pending packet buffer type = %T", pkt))
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}
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}
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// enqueue a packet to be sent once link resolution completes.
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//
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// If the maximum number of pending resolutions is reached, the packets
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@ -151,7 +137,7 @@ func (f *packetsPendingLinkResolution) enqueue(r *Route, gso *GSO, proto tcpip.N
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// The route resolved immediately, so we don't need to wait for link
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// resolution to send the packet.
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f.mu.Unlock()
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return f.writePacketBuffer(routeInfo, gso, proto, pkt)
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return f.nic.writePacketBuffer(routeInfo, gso, proto, pkt)
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case *tcpip.ErrWouldBlock:
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// We need to wait for link resolution to complete.
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default:
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@ -225,7 +211,7 @@ func (f *packetsPendingLinkResolution) dequeuePackets(packets []pendingPacket, l
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for _, p := range packets {
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if success {
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p.routeInfo.RemoteLinkAddress = linkAddr
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_, _ = f.writePacketBuffer(p.routeInfo, p.gso, p.proto, p.pkt)
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_, _ = f.nic.writePacketBuffer(p.routeInfo, p.gso, p.proto, p.pkt)
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} else {
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f.incrementOutgoingPacketErrors(p.proto, p.pkt)
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