Fix shim deadlock when joining an existing pid namespace (#290)

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

containerd-shim/main.go

@@ -115,6 +115,7 @@ func start(log *os.File) error {
 			// runtime has exited so the shim can also exit
 			if exitShim {
 				// Let containerd take care of calling the runtime delete
+				f.Close()
 				p.Wait()
 				return nil
 			}

runtime/runtime_test.go

@@ -1,6 +1,7 @@
 package runtime
 
 import (
+	"flag"
 	"fmt"
 	"io"
 	"os"
@@ -9,14 +10,13 @@ import (
 	"syscall"
 	"testing"
 	"time"
-	"flag"
 
 	utils "github.com/docker/containerd/testutils"
 )
 
 var (
-	devNull = "/dev/null"
-	stdin   io.WriteCloser
+	devNull     = "/dev/null"
+	stdin       io.WriteCloser
 	runtimeTool = flag.String("runtime", "runc", "Runtime to use for this test")
 )
 
@@ -163,13 +163,17 @@ func BenchmarkBusyboxSh(b *testing.B) {
 }
 
 func benchmarkStartContainer(b *testing.B, c Container, s Stdio, bundleName string) {
-	if _, err := c.Start("", s); err != nil {
+	p, err := c.Start("", s)
+	if err != nil {
 		b.Fatalf("Error starting container %v", err)
 	}
 
 	kill := exec.Command(c.Runtime(), "kill", bundleName, "KILL")
 	kill.Run()
 
+	p.Wait()
+	c.Delete()
+
 	// wait for kill to finish. selected wait time is arbitrary
 	time.Sleep(500 * time.Millisecond)
 

supervisor/delete.go

@@ -14,6 +14,7 @@ type DeleteTask struct {
 	Status  int
 	PID     string
 	NoEvent bool
+	Process runtime.Process
 }
 
 func (s *Supervisor) delete(t *DeleteTask) error {
@@ -22,6 +23,9 @@ func (s *Supervisor) delete(t *DeleteTask) error {
 		if err := s.deleteContainer(i.container); err != nil {
 			logrus.WithField("error", err).Error("containerd: deleting container")
 		}
+		if t.Process != nil {
+			t.Process.Wait()
+		}
 		if !t.NoEvent {
 			s.notifySubscribers(Event{
 				Type:      StateExit,

supervisor/exit.go

@@ -46,9 +46,10 @@ func (s *Supervisor) exit(t *ExitTask) error {
 	}
 	container := proc.Container()
 	ne := &DeleteTask{
-		ID:     container.ID(),
-		Status: status,
-		PID:    proc.ID(),
+		ID:      container.ID(),
+		Status:  status,
+		PID:     proc.ID(),
+		Process: proc,
 	}
 	s.delete(ne)
 
@@ -72,6 +73,7 @@ func (s *Supervisor) execExit(t *ExecExitTask) error {
 	if err := container.RemoveProcess(t.PID); err != nil {
 		logrus.WithField("error", err).Error("containerd: find container for pid")
 	}
+	t.Process.Wait()
 	s.notifySubscribers(Event{
 		Timestamp: time.Now(),
 		ID:        t.ID,

supervisor/supervisor.go

@@ -282,7 +282,6 @@ func (s *Supervisor) SendTask(evt Task) {
 
 func (s *Supervisor) exitHandler() {
 	for p := range s.monitor.Exits() {
-		p.Wait()
 		e := &ExitTask{
 			Process: p,
 		}

supervisor/worker.go

@@ -51,6 +51,7 @@ func (w *worker) Start() {
 			evt := &DeleteTask{
 				ID:      t.Container.ID(),
 				NoEvent: true,
+				Process: process,
 			}
 			w.s.SendTask(evt)
 			continue
@@ -66,6 +67,7 @@ func (w *worker) Start() {
 			evt := &DeleteTask{
 				ID:      t.Container.ID(),
 				NoEvent: true,
+				Process: process,
 			}
 			w.s.SendTask(evt)
 			continue
@@ -76,6 +78,7 @@ func (w *worker) Start() {
 			evt := &DeleteTask{
 				ID:      t.Container.ID(),
 				NoEvent: true,
+				Process: process,
 			}
 			w.s.SendTask(evt)
 			continue