4 files changed, 41 insertions, 29 deletions
diff --git a/pkg/sleep/sleep_unsafe.go b/pkg/sleep/sleep_unsafe.go
index f68c12620..118805492 100644
--- a/pkg/sleep/sleep_unsafe.go
+++ b/pkg/sleep/sleep_unsafe.go
@@ -75,6 +75,8 @@ package sleep
 import (
 	"sync/atomic"
 	"unsafe"
+
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 const (
@@ -323,7 +325,12 @@ func (s *Sleeper) enqueueAssertedWaker(w *Waker) {
 //
 // This struct is thread-safe, that is, its methods can be called concurrently
 // by multiple goroutines.
+//
+// Note, it is not safe to copy a Waker as its fields are modified by value
+// (the pointer fields are individually modified with atomic operations).
 type Waker struct {
+	_ sync.NoCopy
+
 	// s is the sleeper that this waker can wake up. Only one sleeper at a
 	// time is allowed. This field can have three classes of values:
 	// nil -- the waker is not asserted: it either is not associated with
diff --git a/pkg/sync/nocopy.go b/pkg/sync/nocopy.go
new file mode 100644
index 000000000..722b29501
--- /dev/null
+++ b/pkg/sync/nocopy.go
@@ -0,0 +1,28 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sync
+
+// NoCopy may be embedded into structs which must not be copied
+// after the first use.
+//
+// See https://golang.org/issues/8005#issuecomment-190753527
+// for details.
+type NoCopy struct{}
+
+// Lock is a no-op used by -copylocks checker from `go vet`.
+func (*NoCopy) Lock() {}
+
+// Unlock is a no-op used by -copylocks checker from `go vet`.
+func (*NoCopy) Unlock() {}
diff --git a/pkg/tcpip/stack/packet_buffer.go b/pkg/tcpip/stack/packet_buffer.go
index 1b5da6017..e3556d5d2 100644
--- a/pkg/tcpip/stack/packet_buffer.go
+++ b/pkg/tcpip/stack/packet_buffer.go
@@ -14,6 +14,7 @@
 package stack
 
 import (
+	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 )
@@ -24,7 +25,7 @@ import (
 // multiple endpoints. Clone() should be called in such cases so that
 // modifications to the Data field do not affect other copies.
 type PacketBuffer struct {
-	_ noCopy
+	_ sync.NoCopy
 
 	// PacketBufferEntry is used to build an intrusive list of
 	// PacketBuffers.
@@ -102,14 +103,3 @@ func (pk *PacketBuffer) Clone() *PacketBuffer {
 		NatDone:               pk.NatDone,
 	}
 }
-
-// noCopy may be embedded into structs which must not be copied
-// after the first use.
-//
-// See https://golang.org/issues/8005#issuecomment-190753527
-// for details.
-type noCopy struct{}
-
-// Lock is a no-op used by -copylocks checker from `go vet`.
-func (*noCopy) Lock()   {}
-func (*noCopy) Unlock() {}
diff --git a/pkg/tcpip/timer.go b/pkg/tcpip/timer.go
index 59f3b391f..5554c573f 100644
--- a/pkg/tcpip/timer.go
+++ b/pkg/tcpip/timer.go
@@ -15,8 +15,9 @@
 package tcpip
 
 import (
-	"sync"
 	"time"
+
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 // cancellableTimerInstance is a specific instance of CancellableTimer.
@@ -92,6 +93,8 @@ func (t *cancellableTimerInstance) stop() {
 // Note, it is not safe to copy a CancellableTimer as its timer instance creates
 // a closure over the address of the CancellableTimer.
 type CancellableTimer struct {
+	_ sync.NoCopy
+
 	// The active instance of a cancellable timer.
 	instance cancellableTimerInstance
 
@@ -157,22 +160,6 @@ func (t *CancellableTimer) Reset(d time.Duration) {
 	}
 }
 
-// Lock is a no-op used by the copylocks checker from go vet.
-//
-// See CancellableTimer for details about why it shouldn't be copied.
-//
-// See https://github.com/golang/go/issues/8005#issuecomment-190753527 for more
-// details about the copylocks checker.
-func (*CancellableTimer) Lock() {}
-
-// Unlock is a no-op used by the copylocks checker from go vet.
-//
-// See CancellableTimer for details about why it shouldn't be copied.
-//
-// See https://github.com/golang/go/issues/8005#issuecomment-190753527 for more
-// details about the copylocks checker.
-func (*CancellableTimer) Unlock() {}
-
 // NewCancellableTimer returns an unscheduled CancellableTimer with the given
 // locker and fn.
 //