Merge release-20201027.0-54-gc22067d3d (automated)

1 files changed, 19 insertions, 2 deletions

diff --git a/pkg/tcpip/stack/neighbor_entry.go b/pkg/tcpip/stack/neighbor_entry.go
index aec77610d..493e48031 100644
--- a/pkg/tcpip/stack/neighbor_entry.go
+++ b/pkg/tcpip/stack/neighbor_entry.go
@@ -17,12 +17,19 @@ package stack
 import (
 	"fmt"
 	"sync"
+	"time"
 
 	"gvisor.dev/gvisor/pkg/sleep"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 )
 
+const (
+	// immediateDuration is a duration of zero for scheduling work that needs to
+	// be done immediately but asynchronously to avoid deadlock.
+	immediateDuration time.Duration = 0
+)
+
 // NeighborEntry describes a neighboring device in the local network.
 type NeighborEntry struct {
 	Addr           tcpip.Address
@@ -242,7 +249,12 @@ func (e *neighborEntry) setStateLocked(next NeighborState) {
 			e.job.Schedule(config.RetransmitTimer)
 		}
 
-		sendUnicastProbe()
+		// Send a probe in another gorountine to free this thread of execution
+		// for finishing the state transition. This is necessary to avoid
+		// deadlock where sending and processing probes are done synchronously,
+		// such as loopback and integration tests.
+		e.job = e.nic.stack.newJob(&e.mu, sendUnicastProbe)
+		e.job.Schedule(immediateDuration)
 
 	case Failed:
 		e.notifyWakersLocked()
@@ -324,7 +336,12 @@ func (e *neighborEntry) handlePacketQueuedLocked(localAddr tcpip.Address) {
 			e.job.Schedule(config.RetransmitTimer)
 		}
 
-		sendMulticastProbe()
+		// Send a probe in another gorountine to free this thread of execution
+		// for finishing the state transition. This is necessary to avoid
+		// deadlock where sending and processing probes are done synchronously,
+		// such as loopback and integration tests.
+		e.job = e.nic.stack.newJob(&e.mu, sendMulticastProbe)
+		e.job.Schedule(immediateDuration)
 
 	case Stale:
 		e.setStateLocked(Delay)