有一段 Go 的代码报了 race，但不知道会有什么潜在问题，各位大佬帮忙指点一下

[PureWhiteWu]

代码如下：

package main

import (
	"sync"
	"sync/atomic"
)

func main() {
	var n int32
	var m sync.RWMutex
	go func() {
		for {
			atomic.LoadInt32(&n)
		}
	}()
	go func() {
		for {
			m.RLock()
			atomic.AddInt32(&n, 1)
			m.RUnlock()
		}
	}()
	go func() {
		for {
			m.Lock()
			n = 0
			m.Unlock()
		}
	}()
	go func() {
		for {
			m.Lock()
			n -= 1
			m.Unlock()
		}
	}()
    // do something to keep goroutines running here
	......
}

playground link: https://play.golang.org/p/Mrdetw46mXR

race 内容：

$ go run -race main.go
==================
WARNING: DATA RACE
Write at 0x00c000096000 by goroutine 7:
  main.main.func3()
      /Users/purewhite/go/src/xxx/main.go:26 +0x46

Previous read at 0x00c000096000 by goroutine 5:
  sync/atomic.LoadInt32()
      /usr/local/Cellar/go/1.12.6/libexec/src/runtime/race_amd64.s:206 +0xb
  main.main.func1()
      /Users/purewhite/go/src/xxx/main.go:13 +0x38

Goroutine 7 (running) created at:
  main.main()
      /Users/purewhite/go/src/xxx/main.go:23 +0x115

Goroutine 5 (running) created at:
  main.main()
      /Users/purewhite/go/src/xxx/main.go:11 +0xbd
==================
Found 1 data race(s)
exit status 66

[fork]

把 mutex 去了,
用 atomic.StoreInt32(&n, 0) 代替 n = 0
用 atomic.AddInt32(&n, -1) 代替 n -= 1

[100knights]

为啥你修改要用读锁?

[liulaomo]

这写法看着真别扭。很明显第一个协程和第三第四个有竞争。
按照你这种写法，你可以把第一个和第二个一样加个读锁。

[whoami9894]

为什么原子操作还加锁

[reus]

要么全部用锁，要么全部用原子操作，混用就是 race 啊