8 files changed, 26 insertions, 23 deletions
diff --git a/pkg/flipcall/BUILD b/pkg/flipcall/BUILD
index 5643d5f26..9c5ad500b 100644
--- a/pkg/flipcall/BUILD
+++ b/pkg/flipcall/BUILD
@@ -1,7 +1,6 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 
-package(licenses = ["notice"])
+licenses(["notice"])
 
 go_library(
     name = "flipcall",
@@ -13,13 +12,12 @@ go_library(
         "io.go",
         "packet_window_allocator.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/flipcall",
     visibility = ["//visibility:public"],
     deps = [
         "//pkg/abi/linux",
         "//pkg/log",
         "//pkg/memutil",
-        "//third_party/gvsync",
+        "//pkg/sync",
     ],
 )
 
@@ -30,5 +28,6 @@ go_test(
         "flipcall_example_test.go",
         "flipcall_test.go",
     ],
-    embed = [":flipcall"],
+    library = ":flipcall",
+    deps = ["//pkg/sync"],
 )
diff --git a/pkg/flipcall/ctrl_futex.go b/pkg/flipcall/ctrl_futex.go
index 8390915a2..e7c3a3a0b 100644
--- a/pkg/flipcall/ctrl_futex.go
+++ b/pkg/flipcall/ctrl_futex.go
@@ -113,7 +113,7 @@ func (ep *Endpoint) enterFutexWait() error {
 		return nil
 	case epsBlocked | epsShutdown:
 		atomic.AddInt32(&ep.ctrl.state, -epsBlocked)
-		return shutdownError{}
+		return ShutdownError{}
 	default:
 		// Most likely due to ep.enterFutexWait() being called concurrently
 		// from multiple goroutines.
diff --git a/pkg/flipcall/flipcall.go b/pkg/flipcall/flipcall.go
index 386cee42c..3cdb576e1 100644
--- a/pkg/flipcall/flipcall.go
+++ b/pkg/flipcall/flipcall.go
@@ -136,8 +136,8 @@ func (ep *Endpoint) unmapPacket() {
 
 // Shutdown causes concurrent and future calls to ep.Connect(), ep.SendRecv(),
 // ep.RecvFirst(), and ep.SendLast(), as well as the same calls in the peer
-// Endpoint, to unblock and return errors. It does not wait for concurrent
-// calls to return. Successive calls to Shutdown have no effect.
+// Endpoint, to unblock and return ShutdownErrors. It does not wait for
+// concurrent calls to return. Successive calls to Shutdown have no effect.
 //
 // Shutdown is the only Endpoint method that may be called concurrently with
 // other methods on the same Endpoint.
@@ -154,10 +154,12 @@ func (ep *Endpoint) isShutdownLocally() bool {
 	return atomic.LoadUint32(&ep.shutdown) != 0
 }
 
-type shutdownError struct{}
+// ShutdownError is returned by most Endpoint methods after Endpoint.Shutdown()
+// has been called.
+type ShutdownError struct{}
 
 // Error implements error.Error.
-func (shutdownError) Error() string {
+func (ShutdownError) Error() string {
 	return "flipcall connection shutdown"
 }
 
diff --git a/pkg/flipcall/flipcall_example_test.go b/pkg/flipcall/flipcall_example_test.go
index 8d88b845d..2e28a149a 100644
--- a/pkg/flipcall/flipcall_example_test.go
+++ b/pkg/flipcall/flipcall_example_test.go
@@ -17,7 +17,8 @@ package flipcall
 import (
 	"bytes"
 	"fmt"
-	"sync"
+
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 func Example() {
diff --git a/pkg/flipcall/flipcall_test.go b/pkg/flipcall/flipcall_test.go
index 168a487ec..33fd55a44 100644
--- a/pkg/flipcall/flipcall_test.go
+++ b/pkg/flipcall/flipcall_test.go
@@ -16,9 +16,10 @@ package flipcall
 
 import (
 	"runtime"
-	"sync"
 	"testing"
 	"time"
+
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 var testPacketWindowSize = pageSize
diff --git a/pkg/flipcall/flipcall_unsafe.go b/pkg/flipcall/flipcall_unsafe.go
index a37952637..ac974b232 100644
--- a/pkg/flipcall/flipcall_unsafe.go
+++ b/pkg/flipcall/flipcall_unsafe.go
@@ -18,7 +18,7 @@ import (
 	"reflect"
 	"unsafe"
 
-	"gvisor.dev/gvisor/third_party/gvsync"
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 // Packets consist of a 16-byte header followed by an arbitrarily-sized
@@ -75,13 +75,13 @@ func (ep *Endpoint) Data() []byte {
 var ioSync int64
 
 func raceBecomeActive() {
-	if gvsync.RaceEnabled {
-		gvsync.RaceAcquire((unsafe.Pointer)(&ioSync))
+	if sync.RaceEnabled {
+		sync.RaceAcquire((unsafe.Pointer)(&ioSync))
 	}
 }
 
 func raceBecomeInactive() {
-	if gvsync.RaceEnabled {
-		gvsync.RaceReleaseMerge((unsafe.Pointer)(&ioSync))
+	if sync.RaceEnabled {
+		sync.RaceReleaseMerge((unsafe.Pointer)(&ioSync))
 	}
 }
diff --git a/pkg/flipcall/futex_linux.go b/pkg/flipcall/futex_linux.go
index b127a2bbb..168c1ccff 100644
--- a/pkg/flipcall/futex_linux.go
+++ b/pkg/flipcall/futex_linux.go
@@ -61,7 +61,7 @@ func (ep *Endpoint) futexSwitchToPeer() error {
 	if !atomic.CompareAndSwapUint32(ep.connState(), ep.activeState, ep.inactiveState) {
 		switch cs := atomic.LoadUint32(ep.connState()); cs {
 		case csShutdown:
-			return shutdownError{}
+			return ShutdownError{}
 		default:
 			return fmt.Errorf("unexpected connection state before FUTEX_WAKE: %v", cs)
 		}
@@ -81,14 +81,14 @@ func (ep *Endpoint) futexSwitchFromPeer() error {
 			return nil
 		case ep.inactiveState:
 			if ep.isShutdownLocally() {
-				return shutdownError{}
+				return ShutdownError{}
 			}
 			if err := ep.futexWaitConnState(ep.inactiveState); err != nil {
 				return fmt.Errorf("failed to FUTEX_WAIT for peer Endpoint: %v", err)
 			}
 			continue
 		case csShutdown:
-			return shutdownError{}
+			return ShutdownError{}
 		default:
 			return fmt.Errorf("unexpected connection state before FUTEX_WAIT: %v", cs)
 		}
diff --git a/pkg/flipcall/packet_window_allocator.go b/pkg/flipcall/packet_window_allocator.go
index ccb918fab..af9cc3d21 100644
--- a/pkg/flipcall/packet_window_allocator.go
+++ b/pkg/flipcall/packet_window_allocator.go
@@ -134,7 +134,7 @@ func (pwa *PacketWindowAllocator) Allocate(size int) (PacketWindowDescriptor, er
 	start := pwa.nextAlloc
 	pwa.nextAlloc = end
 	return PacketWindowDescriptor{
-		FD:     pwa.fd,
+		FD:     pwa.FD(),
 		Offset: start,
 		Length: size,
 	}, nil
@@ -158,7 +158,7 @@ func (pwa *PacketWindowAllocator) ensureFileSize(min int64) error {
 		}
 		newSize = newNewSize
 	}
-	if err := syscall.Ftruncate(pwa.fd, newSize); err != nil {
+	if err := syscall.Ftruncate(pwa.FD(), newSize); err != nil {
 		return fmt.Errorf("ftruncate failed: %v", err)
 	}
 	pwa.fileSize = newSize