1 files changed, 29 insertions, 12 deletions
diff --git a/libgo/go/expvar/expvar.go b/libgo/go/expvar/expvar.go
index 1919296ea8f..b06599505fc 100644
--- a/libgo/go/expvar/expvar.go
+++ b/libgo/go/expvar/expvar.go
@@ -41,10 +41,14 @@ type Var interface {
 // Int is a 64-bit integer variable that satisfies the Var interface.
 type Int struct {
 	i  int64
-	mu sync.Mutex
+	mu sync.RWMutex
 }
 
-func (v *Int) String() string { return strconv.FormatInt(v.i, 10) }
+func (v *Int) String() string {
+	v.mu.RLock()
+	defer v.mu.RUnlock()
+	return strconv.FormatInt(v.i, 10)
+}
 
 func (v *Int) Add(delta int64) {
 	v.mu.Lock()
@@ -61,10 +65,14 @@ func (v *Int) Set(value int64) {
 // Float is a 64-bit float variable that satisfies the Var interface.
 type Float struct {
 	f  float64
-	mu sync.Mutex
+	mu sync.RWMutex
 }
 
-func (v *Float) String() string { return strconv.FormatFloat(v.f, 'g', -1, 64) }
+func (v *Float) String() string {
+	v.mu.RLock()
+	defer v.mu.RUnlock()
+	return strconv.FormatFloat(v.f, 'g', -1, 64)
+}
 
 // Add adds delta to v.
 func (v *Float) Add(delta float64) {
@@ -95,17 +103,17 @@ type KeyValue struct {
 func (v *Map) String() string {
 	v.mu.RLock()
 	defer v.mu.RUnlock()
-	b := new(bytes.Buffer)
-	fmt.Fprintf(b, "{")
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "{")
 	first := true
 	for key, val := range v.m {
 		if !first {
-			fmt.Fprintf(b, ", ")
+			fmt.Fprintf(&b, ", ")
 		}
-		fmt.Fprintf(b, "\"%s\": %v", key, val)
+		fmt.Fprintf(&b, "\"%s\": %v", key, val)
 		first = false
 	}
-	fmt.Fprintf(b, "}")
+	fmt.Fprintf(&b, "}")
 	return b.String()
 }
 
@@ -180,12 +188,21 @@ func (v *Map) Do(f func(KeyValue)) {
 
 // String is a string variable, and satisfies the Var interface.
 type String struct {
-	s string
+	s  string
+	mu sync.RWMutex
 }
 
-func (v *String) String() string { return strconv.Quote(v.s) }
+func (v *String) String() string {
+	v.mu.RLock()
+	defer v.mu.RUnlock()
+	return strconv.Quote(v.s)
+}
 
-func (v *String) Set(value string) { v.s = value }
+func (v *String) Set(value string) {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+	v.s = value
+}
 
 // Func implements Var by calling the function
 // and formatting the returned value using JSON.