windows: add race annotations to Windows ReadFile and WriteFile

Follow CL 392774 which changed Windows ReadFile and WriteFile in package
syscall.

For golang/go#51618

Change-Id: I0f8046adb0f8145bd0775a3b5399647897cf19ce
Reviewed-on: https://go-review.googlesource.com/c/sys/+/392814
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

windows/syscall_windows.go

@@ -186,8 +186,8 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	GetNamedPipeInfo(pipe Handle, flags *uint32, outSize *uint32, inSize *uint32, maxInstances *uint32) (err error)
 //sys	GetNamedPipeHandleState(pipe Handle, state *uint32, curInstances *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32, userName *uint16, maxUserNameSize uint32) (err error) = GetNamedPipeHandleStateW
 //sys	SetNamedPipeHandleState(pipe Handle, state *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32) (err error) = SetNamedPipeHandleState
-//sys	ReadFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error)
+//sys	readFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error) = ReadFile
-//sys	WriteFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error)
+//sys	writeFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error) = WriteFile
 //sys	GetOverlappedResult(handle Handle, overlapped *Overlapped, done *uint32, wait bool) (err error)
 //sys	SetFilePointer(handle Handle, lowoffset int32, highoffsetptr *int32, whence uint32) (newlowoffset uint32, err error) [failretval==0xffffffff]
 //sys	CloseHandle(handle Handle) (err error)
@@ -549,12 +549,6 @@ func Read(fd Handle, p []byte) (n int, err error) {
 		}
 		return 0, e
 	}
-	if raceenabled {
-		if done > 0 {
-			raceWriteRange(unsafe.Pointer(&p[0]), int(done))
-		}
-		raceAcquire(unsafe.Pointer(&ioSync))
-	}
 	return int(done), nil
 }
 
@@ -567,12 +561,31 @@ func Write(fd Handle, p []byte) (n int, err error) {
 	if e != nil {
 		return 0, e
 	}
-	if raceenabled && done > 0 {
-		raceReadRange(unsafe.Pointer(&p[0]), int(done))
-	}
 	return int(done), nil
 }
 
+func ReadFile(fd Handle, p []byte, done *uint32, overlapped *Overlapped) error {
+	err := readFile(fd, p, done, overlapped)
+	if raceenabled {
+		if *done > 0 {
+			raceWriteRange(unsafe.Pointer(&p[0]), int(*done))
+		}
+		raceAcquire(unsafe.Pointer(&ioSync))
+	}
+	return err
+}
+
+func WriteFile(fd Handle, p []byte, done *uint32, overlapped *Overlapped) error {
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	err := writeFile(fd, p, done, overlapped)
+	if raceenabled && *done > 0 {
+		raceReadRange(unsafe.Pointer(&p[0]), int(*done))
+	}
+	return err
+}
+
 var ioSync int64
 
 func Seek(fd Handle, offset int64, whence int) (newoffset int64, err error) {

windows/zsyscall_windows.go

@@ -2761,7 +2761,7 @@ func ReadDirectoryChanges(handle Handle, buf *byte, buflen uint32, watchSubTree
 	return
 }
 
-func ReadFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error) {
+func readFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error) {
 	var _p0 *byte
 	if len(buf) > 0 {
 		_p0 = &buf[0]
@@ -3203,7 +3203,7 @@ func WriteConsole(console Handle, buf *uint16, towrite uint32, written *uint32,
 	return
 }
 
-func WriteFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error) {
+func writeFile(handle Handle, buf []byte, done *uint32, overlapped *Overlapped) (err error) {
 	var _p0 *byte
 	if len(buf) > 0 {
 		_p0 = &buf[0]