3 files changed, 17 insertions, 58 deletions
diff --git a/pkg/tcpip/stack/tcp.go b/pkg/tcpip/stack/tcp.go
index e90c1a770..90a8ba6cf 100644
--- a/pkg/tcpip/stack/tcp.go
+++ b/pkg/tcpip/stack/tcp.go
@@ -380,9 +380,6 @@ type TCPSndBufState struct {
 	// SndClosed indicates that the endpoint has been closed for sends.
 	SndClosed bool
 
-	// SndBufInQueue is the number of bytes in the send queue.
-	SndBufInQueue seqnum.Size
-
 	// PacketTooBigCount is used to notify the main protocol routine how
 	// many times a "packet too big" control packet is received.
 	PacketTooBigCount int
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index f86450298..e39d1623d 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -909,30 +909,13 @@ func (e *endpoint) sendRaw(data buffer.VectorisedView, flags header.TCPFlags, se
 	return err
 }
 
-func (e *endpoint) handleWrite() {
-	e.sndQueueInfo.sndQueueMu.Lock()
-	next := e.drainSendQueueLocked()
-	e.sndQueueInfo.sndQueueMu.Unlock()
-
-	e.sendData(next)
-}
-
-// Move packets from send queue to send list.
-//
-// Precondition: e.sndBufMu must be locked.
-func (e *endpoint) drainSendQueueLocked() *segment {
-	first := e.sndQueueInfo.sndQueue.Front()
-	if first != nil {
-		e.snd.writeList.PushBackList(&e.sndQueueInfo.sndQueue)
-		e.sndQueueInfo.SndBufInQueue = 0
-	}
-	return first
-}
-
 // Precondition: e.mu must be locked.
 func (e *endpoint) sendData(next *segment) {
 	// Initialize the next segment to write if it's currently nil.
 	if e.snd.writeNext == nil {
+		if next == nil {
+			return
+		}
 		e.snd.writeNext = next
 	}
 
@@ -940,17 +923,6 @@ func (e *endpoint) sendData(next *segment) {
 	e.snd.sendData()
 }
 
-func (e *endpoint) handleClose() {
-	if !e.EndpointState().connected() {
-		return
-	}
-	// Drain the send queue.
-	e.handleWrite()
-
-	// Mark send side as closed.
-	e.snd.Closed = true
-}
-
 // resetConnectionLocked puts the endpoint in an error state with the given
 // error code and sends a RST if and only if the error is not ErrConnectionReset
 // indicating that the connection is being reset due to receiving a RST. This
@@ -1402,14 +1374,7 @@ func (e *endpoint) protocolMainLoop(handshake bool, wakerInitDone chan<- struct{
 		{
 			w: &e.sndQueueInfo.sndWaker,
 			f: func() tcpip.Error {
-				e.handleWrite()
-				return nil
-			},
-		},
-		{
-			w: &e.sndQueueInfo.sndCloseWaker,
-			f: func() tcpip.Error {
-				e.handleClose()
+				e.sendData(nil /* next */)
 				return nil
 			},
 		},
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 242e6b7f8..4acddc959 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -293,16 +293,9 @@ type sndQueueInfo struct {
 	sndQueueMu sync.Mutex `state:"nosave"`
 	stack.TCPSndBufState
 
-	// sndQueue holds segments that are ready to be sent.
-	sndQueue segmentList `state:"wait"`
-
-	// sndWaker is used to signal the protocol goroutine when segments are
-	// added to the `sndQueue`.
+	// sndWaker is used to signal the protocol goroutine when there may be
+	// segments that need to be sent.
 	sndWaker sleep.Waker `state:"manual"`
-
-	// sndCloseWaker is used to notify the protocol goroutine when the send
-	// side is closed.
-	sndCloseWaker sleep.Waker `state:"manual"`
 }
 
 // rcvQueueInfo contains the endpoint's rcvQueue and associated metadata.
@@ -1558,10 +1551,9 @@ func (e *endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, tcp
 		// Add data to the send queue.
 		s := newOutgoingSegment(e.TransportEndpointInfo.ID, e.stack.Clock(), v)
 		e.sndQueueInfo.SndBufUsed += len(v)
-		e.sndQueueInfo.SndBufInQueue += seqnum.Size(len(v))
-		e.sndQueueInfo.sndQueue.PushBack(s)
+		e.snd.writeList.PushBack(s)
 
-		return e.drainSendQueueLocked(), len(v), nil
+		return s, len(v), nil
 	}()
 	// Return if either we didn't queue anything or if an error occurred while
 	// attempting to queue data.
@@ -2314,7 +2306,7 @@ func (e *endpoint) connect(addr tcpip.FullAddress, handshake bool, run bool) tcp
 	// connection setting here.
 	if !handshake {
 		e.segmentQueue.mu.Lock()
-		for _, l := range []segmentList{e.segmentQueue.list, e.sndQueueInfo.sndQueue, e.snd.writeList} {
+		for _, l := range []segmentList{e.segmentQueue.list, e.snd.writeList} {
 			for s := l.Front(); s != nil; s = s.Next() {
 				s.id = e.TransportEndpointInfo.ID
 				e.sndQueueInfo.sndWaker.Assert()
@@ -2391,12 +2383,17 @@ func (e *endpoint) shutdownLocked(flags tcpip.ShutdownFlags) tcpip.Error {
 
 			// Queue fin segment.
 			s := newOutgoingSegment(e.TransportEndpointInfo.ID, e.stack.Clock(), nil)
-			e.sndQueueInfo.sndQueue.PushBack(s)
-			e.sndQueueInfo.SndBufInQueue++
+			e.snd.writeList.PushBack(s)
 			// Mark endpoint as closed.
 			e.sndQueueInfo.SndClosed = true
 			e.sndQueueInfo.sndQueueMu.Unlock()
-			e.handleClose()
+
+			// Drain the send queue.
+			e.sendData(s)
+
+			// Mark send side as closed.
+			e.snd.Closed = true
+
 			// Wake up any writers that maybe waiting for the stream to become
 			// writable.
 			e.waiterQueue.Notify(waiter.WritableEvents)