os: data race in epipecheck()

[dvyukov]

When running proprietary code under ThreadSanitizer I see the following reports:

WARNING: DATA RACE at 0x000040115140
Write by goroutine 104:
  os.epipecheck()
      src/pkg/os/file_posix.go:23 +0x135
  os.(*File).Write()
      src/pkg/os/file.go:144 +0xec
  ...
Previous write by goroutine 99:
  os.epipecheck()
      src/pkg/os/file_posix.go:23 +0x135
  os.(*File).Write()
      src/pkg/os/file.go:144 +0xec
  ...

epipecheck() clearly has a data race on file.npipe:

func epipecheck(file *File, e error) {
    if e == syscall.EPIPE {
        file.nepipe++
        if file.nepipe >= 10 {
            sigpipe()
        }
    } else {
        file.nepipe = 0
    }
}

[dvyukov]

Comment 1:

Owner changed to @dvyukov.

Status changed to Accepted.

[dvyukov]

Comment 2:

This issue was closed by revision ab9cced.

Status changed to Fixed.