1 files changed, 18 insertions, 0 deletions
diff --git a/libgo/go/os/exec_unix.go b/libgo/go/os/exec_unix.go
index ed97f85e22..c4999db57f 100644
--- a/libgo/go/os/exec_unix.go
+++ b/libgo/go/os/exec_unix.go
@@ -17,6 +17,22 @@ func (p *Process) wait() (ps *ProcessState, err error) {
 	if p.Pid == -1 {
 		return nil, syscall.EINVAL
 	}
+
+	// If we can block until Wait4 will succeed immediately, do so.
+	ready, err := p.blockUntilWaitable()
+	if err != nil {
+		return nil, err
+	}
+	if ready {
+		// Mark the process done now, before the call to Wait4,
+		// so that Process.signal will not send a signal.
+		p.setDone()
+		// Acquire a write lock on sigMu to wait for any
+		// active call to the signal method to complete.
+		p.sigMu.Lock()
+		p.sigMu.Unlock()
+	}
+
 	var status syscall.WaitStatus
 	var rusage syscall.Rusage
 	pid1, e := syscall.Wait4(p.Pid, &status, 0, &rusage)
@@ -43,6 +59,8 @@ func (p *Process) signal(sig Signal) error {
 	if p.Pid == 0 {
 		return errors.New("os: process not initialized")
 	}
+	p.sigMu.RLock()
+	defer p.sigMu.RUnlock()
 	if p.done() {
 		return errFinished
 	}