Merge release-20200323.0-156-g28212b3 (automated)

5 files changed, 42 insertions, 30 deletions

diff --git a/pkg/tcpip/link/channel/channel.go b/pkg/tcpip/link/channel/channel.go
index b4a0ae53d..9bf67686d 100755
--- a/pkg/tcpip/link/channel/channel.go
+++ b/pkg/tcpip/link/channel/channel.go
@@ -50,13 +50,11 @@ type NotificationHandle struct {
 }
 
 type queue struct {
+	// c is the outbound packet channel.
+	c chan PacketInfo
 	// mu protects fields below.
-	mu sync.RWMutex
-	// c is the outbound packet channel. Sending to c should hold mu.
-	c        chan PacketInfo
-	numWrite int
-	numRead  int
-	notify   []*NotificationHandle
+	mu     sync.RWMutex
+	notify []*NotificationHandle
 }
 
 func (q *queue) Close() {
@@ -64,11 +62,8 @@ func (q *queue) Close() {
 }
 
 func (q *queue) Read() (PacketInfo, bool) {
-	q.mu.Lock()
-	defer q.mu.Unlock()
 	select {
 	case p := <-q.c:
-		q.numRead++
 		return p, true
 	default:
 		return PacketInfo{}, false
@@ -76,15 +71,8 @@ func (q *queue) Read() (PacketInfo, bool) {
 }
 
 func (q *queue) ReadContext(ctx context.Context) (PacketInfo, bool) {
-	// We have to receive from channel without holding the lock, since it can
-	// block indefinitely. This will cause a window that numWrite - numRead
-	// produces a larger number, but won't go to negative. numWrite >= numRead
-	// still holds.
 	select {
 	case pkt := <-q.c:
-		q.mu.Lock()
-		defer q.mu.Unlock()
-		q.numRead++
 		return pkt, true
 	case <-ctx.Done():
 		return PacketInfo{}, false
@@ -93,16 +81,12 @@ func (q *queue) ReadContext(ctx context.Context) (PacketInfo, bool) {
 
 func (q *queue) Write(p PacketInfo) bool {
 	wrote := false
-
-	// It's important to make sure nobody can see numWrite until we increment it,
-	// so numWrite >= numRead holds.
-	q.mu.Lock()
 	select {
 	case q.c <- p:
 		wrote = true
-		q.numWrite++
 	default:
 	}
+	q.mu.Lock()
 	notify := q.notify
 	q.mu.Unlock()
 
@@ -116,13 +100,7 @@ func (q *queue) Write(p PacketInfo) bool {
 }
 
 func (q *queue) Num() int {
-	q.mu.RLock()
-	defer q.mu.RUnlock()
-	n := q.numWrite - q.numRead
-	if n < 0 {
-		panic("numWrite < numRead")
-	}
-	return n
+	return len(q.c)
 }
 
 func (q *queue) AddNotify(notify Notification) *NotificationHandle {
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index aec7126ff..109121dbc 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -681,6 +681,10 @@ type TCPTimeWaitTimeoutOption time.Duration
 // for a handshake till the specified timeout until a segment with data arrives.
 type TCPDeferAcceptOption time.Duration
 
+// TCPMinRTOOption is use by SetSockOpt/GetSockOpt to allow overriding
+// default MinRTO used by the Stack.
+type TCPMinRTOOption time.Duration
+
 // MulticastInterfaceOption is used by SetSockOpt/GetSockOpt to specify a
 // default interface for multicast.
 type MulticastInterfaceOption struct {
diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go
index dce9a1652..91f25c132 100644
--- a/pkg/tcpip/transport/tcp/protocol.go
+++ b/pkg/tcpip/transport/tcp/protocol.go
@@ -105,6 +105,7 @@ type protocol struct {
 	moderateReceiveBuffer      bool
 	tcpLingerTimeout           time.Duration
 	tcpTimeWaitTimeout         time.Duration
+	minRTO                     time.Duration
 	dispatcher                 *dispatcher
 }
 
@@ -272,6 +273,15 @@ func (p *protocol) SetOption(option interface{}) *tcpip.Error {
 		p.mu.Unlock()
 		return nil
 
+	case tcpip.TCPMinRTOOption:
+		if v < 0 {
+			v = tcpip.TCPMinRTOOption(MinRTO)
+		}
+		p.mu.Lock()
+		p.minRTO = time.Duration(v)
+		p.mu.Unlock()
+		return nil
+
 	default:
 		return tcpip.ErrUnknownProtocolOption
 	}
@@ -334,6 +344,12 @@ func (p *protocol) Option(option interface{}) *tcpip.Error {
 		p.mu.RUnlock()
 		return nil
 
+	case *tcpip.TCPMinRTOOption:
+		p.mu.RLock()
+		*v = tcpip.TCPMinRTOOption(p.minRTO)
+		p.mu.RUnlock()
+		return nil
+
 	default:
 		return tcpip.ErrUnknownProtocolOption
 	}
@@ -359,5 +375,6 @@ func NewProtocol() stack.TransportProtocol {
 		tcpLingerTimeout:           DefaultTCPLingerTimeout,
 		tcpTimeWaitTimeout:         DefaultTCPTimeWaitTimeout,
 		dispatcher:                 newDispatcher(runtime.GOMAXPROCS(0)),
+		minRTO:                     MinRTO,
 	}
 }
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go
index 6b7bac37d..d8cfe3115 100644
--- a/pkg/tcpip/transport/tcp/snd.go
+++ b/pkg/tcpip/transport/tcp/snd.go
@@ -15,6 +15,7 @@
 package tcp
 
 import (
+	"fmt"
 	"math"
 	"sync/atomic"
 	"time"
@@ -149,6 +150,9 @@ type sender struct {
 	rtt rtt
 	rto time.Duration
 
+	// minRTO is the minimum permitted value for sender.rto.
+	minRTO time.Duration
+
 	// maxPayloadSize is the maximum size of the payload of a given segment.
 	// It is initialized on demand.
 	maxPayloadSize int
@@ -260,6 +264,13 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint
 	// etc.
 	s.ep.scoreboard = NewSACKScoreboard(uint16(s.maxPayloadSize), iss)
 
+	// Get Stack wide minRTO.
+	var v tcpip.TCPMinRTOOption
+	if err := ep.stack.TransportProtocolOption(ProtocolNumber, &v); err != nil {
+		panic(fmt.Sprintf("unable to get minRTO from stack: %s", err))
+	}
+	s.minRTO = time.Duration(v)
+
 	return s
 }
 
@@ -394,8 +405,8 @@ func (s *sender) updateRTO(rtt time.Duration) {
 
 	s.rto = s.rtt.srtt + 4*s.rtt.rttvar
 	s.rtt.Unlock()
-	if s.rto < MinRTO {
-		s.rto = MinRTO
+	if s.rto < s.minRTO {
+		s.rto = s.minRTO
 	}
 }
 
diff --git a/pkg/tcpip/transport/tcp/tcp_state_autogen.go b/pkg/tcpip/transport/tcp/tcp_state_autogen.go
index b3cb5f986..5ac73e3b7 100755
--- a/pkg/tcpip/transport/tcp/tcp_state_autogen.go
+++ b/pkg/tcpip/transport/tcp/tcp_state_autogen.go
@@ -374,6 +374,7 @@ func (x *sender) save(m state.Map) {
 	m.Save("writeList", &x.writeList)
 	m.Save("rtt", &x.rtt)
 	m.Save("rto", &x.rto)
+	m.Save("minRTO", &x.minRTO)
 	m.Save("maxPayloadSize", &x.maxPayloadSize)
 	m.Save("gso", &x.gso)
 	m.Save("sndWndScale", &x.sndWndScale)
@@ -399,6 +400,7 @@ func (x *sender) load(m state.Map) {
 	m.Load("writeList", &x.writeList)
 	m.Load("rtt", &x.rtt)
 	m.Load("rto", &x.rto)
+	m.Load("minRTO", &x.minRTO)
 	m.Load("maxPayloadSize", &x.maxPayloadSize)
 	m.Load("gso", &x.gso)
 	m.Load("sndWndScale", &x.sndWndScale)