Adjust LockOSThread

Go 1.10 fixed the problem related to thread and namespaces.
Details:
2595fe7fb6
In few words there is no more the possibility to have a go routine
running on a thread that is another namespace.
In this commit some cleanup is done and the method SetNamespace is
being removed. This will save tons of setns syscall, that were happening
way too frequently possibily to make sure that each operation was being
done in the host namespace.
I suspect that also all the drivers not running in a different
namespace would be able to drop also the lock of the OS Thread but
will address it in a different commit

Removed useless LockOSThreads around

Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>

libnetwork/libnetwork_linux_test.go

@@ -850,6 +850,7 @@ func parallelJoin(t *testing.T, rc libnetwork.Sandbox, ep libnetwork.Endpoint, t
 	err = ep.Join(sb)
 
 	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
 	if err != nil {
 		if _, ok := err.(types.ForbiddenError); !ok {
 			t.Fatalf("thread %d: %v", thrNumber, err)
@@ -867,6 +868,7 @@ func parallelLeave(t *testing.T, rc libnetwork.Sandbox, ep libnetwork.Endpoint,
 
 	err = ep.Leave(sb)
 	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
 	if err != nil {
 		if _, ok := err.(types.ForbiddenError); !ok {
 			t.Fatalf("thread %d: %v", thrNumber, err)

libnetwork/ns/init_linux.go

@@ -39,19 +39,6 @@ func Init() {
 	}
 }
 
-// SetNamespace sets the initial namespace handler
-func SetNamespace() error {
-	initOnce.Do(Init)
-	if err := netns.Set(initNs); err != nil {
-		linkInfo, linkErr := getLink()
-		if linkErr != nil {
-			linkInfo = linkErr.Error()
-		}
-		return fmt.Errorf("failed to set to initial namespace, %v, initns fd %d: %v", linkInfo, initNs, err)
-	}
-	return nil
-}
-
 // ParseHandlerInt transforms the namespace handler into an integer
 func ParseHandlerInt() int {
 	return int(getHandler())

libnetwork/osl/namespace_linux.go

@@ -394,13 +394,10 @@ func (n *networkNamespace) InvokeFunc(f func()) error {
 // InitOSContext initializes OS context while configuring network resources
 func InitOSContext() func() {
 	runtime.LockOSThread()
-	if err := ns.SetNamespace(); err != nil {
-		logrus.Error(err)
-	}
 	return runtime.UnlockOSThread
 }
 
-func nsInvoke(path string, prefunc func(nsFD int) error, postfunc func(callerFD int) error) error {
+func nsInvoke(path string, prefunc, postfunc func(int) error) error {
 	defer InitOSContext()()
 
 	newNs, err := netns.GetFromPath(path)
@@ -415,10 +412,17 @@ func nsInvoke(path string, prefunc func(nsFD int) error, postfunc func(callerFD
 		return fmt.Errorf("failed in prefunc: %v", err)
 	}
 
+	// save the current namespace (host namespace)
+	curNs, err := netns.Get()
+	if err != nil {
+		return err
+	}
+	defer curNs.Close()
 	if err = netns.Set(newNs); err != nil {
 		return err
 	}
-	defer ns.SetNamespace()
+	// will restore the previous namespace before unlocking the thread
+	defer netns.Set(curNs)
 
 	// Invoked after the namespace switch.
 	return postfunc(ns.ParseHandlerInt())

libnetwork/osl/sandbox_linux_test.go

@@ -7,7 +7,6 @@ import (
 	"net"
 	"os"
 	"path/filepath"
-	"runtime"
 	"strings"
 	"syscall"
 	"testing"
@@ -199,7 +198,6 @@ func TestDisableIPv6DAD(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new sandbox: %v", err)
 	}
-	runtime.LockOSThread()
 	defer s.Destroy()
 
 	n, ok := s.(*networkNamespace)
@@ -253,7 +251,6 @@ func TestSetInterfaceIP(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new sandbox: %v", err)
 	}
-	runtime.LockOSThread()
 	defer s.Destroy()
 
 	n, ok := s.(*networkNamespace)
@@ -329,7 +326,6 @@ func TestLiveRestore(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new sandbox: %v", err)
 	}
-	runtime.LockOSThread()
 	defer s.Destroy()
 
 	n, ok := s.(*networkNamespace)

libnetwork/osl/sandbox_test.go

@@ -2,7 +2,6 @@ package osl
 
 import (
 	"os"
-	"runtime"
 	"testing"
 
 	"github.com/docker/docker/pkg/reexec"
@@ -80,7 +79,6 @@ func TestSandboxCreateTwice(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new sandbox: %v", err)
 	}
-	runtime.LockOSThread()
 
 	// Create another sandbox with the same key to see if we handle it
 	// gracefully.
@@ -88,7 +86,6 @@ func TestSandboxCreateTwice(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new sandbox: %v", err)
 	}
-	runtime.LockOSThread()
 
 	err = s.Destroy()
 	if err != nil {
@@ -130,7 +127,6 @@ func TestAddRemoveInterface(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new sandbox: %v", err)
 	}
-	runtime.LockOSThread()
 
 	if s.Key() != key {
 		t.Fatalf("s.Key() returned %s. Expected %s", s.Key(), key)

libnetwork/testutils/context_unix.go

@@ -33,8 +33,6 @@ func SetupTestOSContext(t *testing.T) func() {
 	// sure to re-initialize initNs context
 	ns.Init()
 
-	runtime.LockOSThread()
-
 	return func() {
 		if err := syscall.Close(fd); err != nil {
 			t.Logf("Warning: netns closing failed (%v)", err)