os: fix data race on Process.done
Fixes #3969.
R=dvyukov, r, alex.brainman, minux.ma
CC=golang-dev
https://golang.org/cl/6462081
diff --git a/src/pkg/os/exec.go b/src/pkg/os/exec.go
index eb6a4f8..5aea309 100644
--- a/src/pkg/os/exec.go
+++ b/src/pkg/os/exec.go
@@ -6,6 +6,7 @@
import (
"runtime"
+ "sync/atomic"
"syscall"
)
@@ -13,7 +14,7 @@
type Process struct {
Pid int
handle uintptr
- done bool // process has been successfully waited on
+ isdone uint32 // process has been successfully waited on, non zero if true
}
func newProcess(pid int, handle uintptr) *Process {
@@ -22,6 +23,14 @@
return p
}
+func (p *Process) setDone() {
+ atomic.StoreUint32(&p.isdone, 1)
+}
+
+func (p *Process) done() bool {
+ return atomic.LoadUint32(&p.isdone) > 0
+}
+
// ProcAttr holds the attributes that will be applied to a new process
// started by StartProcess.
type ProcAttr struct {
diff --git a/src/pkg/os/exec_plan9.go b/src/pkg/os/exec_plan9.go
index ca2dfbf..2a7a597 100644
--- a/src/pkg/os/exec_plan9.go
+++ b/src/pkg/os/exec_plan9.go
@@ -49,7 +49,7 @@
}
func (p *Process) signal(sig Signal) error {
- if p.done {
+ if p.done() {
return errors.New("os: process already finished")
}
if sig == Kill {
@@ -84,7 +84,7 @@
}
if waitmsg.Pid == p.Pid {
- p.done = true
+ p.setDone()
break
}
}
diff --git a/src/pkg/os/exec_unix.go b/src/pkg/os/exec_unix.go
index ecfe535..fa3ba8a 100644
--- a/src/pkg/os/exec_unix.go
+++ b/src/pkg/os/exec_unix.go
@@ -24,7 +24,7 @@
return nil, NewSyscallError("wait", e)
}
if pid1 != 0 {
- p.done = true
+ p.setDone()
}
ps = &ProcessState{
pid: pid1,
@@ -35,7 +35,7 @@
}
func (p *Process) signal(sig Signal) error {
- if p.done {
+ if p.done() {
return errors.New("os: process already finished")
}
s, ok := sig.(syscall.Signal)
diff --git a/src/pkg/os/exec_windows.go b/src/pkg/os/exec_windows.go
index 5beca4a..4aa2ade 100644
--- a/src/pkg/os/exec_windows.go
+++ b/src/pkg/os/exec_windows.go
@@ -32,7 +32,7 @@
if e != nil {
return nil, NewSyscallError("GetProcessTimes", e)
}
- p.done = true
+ p.setDone()
// NOTE(brainman): It seems that sometimes process is not dead
// when WaitForSingleObject returns. But we do not know any
// other way to wait for it. Sleeping for a while seems to do
@@ -43,7 +43,7 @@
}
func (p *Process) signal(sig Signal) error {
- if p.done {
+ if p.done() {
return errors.New("os: process already finished")
}
if sig == Kill {
