[Race Detector] data race in pkg/hubble.TestRingReader_NextFollow_WithEmptyRing

[tklauser]

https://app.travis-ci.com/github/cilium/cilium/jobs/534366323

=== RUN   TestRingReader_NextFollow_WithEmptyRing
==================
WARNING: DATA RACE
Write at 0x00c0000958f8 by goroutine 56:
  runtime.racewrite()
      <autogenerated>:1 +0x24
  github.com/cilium/cilium/pkg/hubble/container.(*RingReader).Close()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader.go:117 +0x45
  github.com/cilium/cilium/pkg/hubble/container.TestRingReader_NextFollow_WithEmptyRing()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader_test.go:305 +0x652
  testing.tRunner()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1306 +0x47

Previous read at 0x00c0000958f8 by goroutine 57:
  runtime.raceread()
      <autogenerated>:1 +0x24
  github.com/cilium/cilium/pkg/hubble/container.(*RingReader).NextFollow()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader.go:81 +0x1bc
  github.com/cilium/cilium/pkg/hubble/container.TestRingReader_NextFollow_WithEmptyRing.func1()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader_test.go:295 +0x84

Goroutine 56 (running) created at:
  testing.(*T).Run()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1306 +0x726
  testing.runTests.func1()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1598 +0x99
  testing.tRunner()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1259 +0x22f
  testing.runTests()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1596 +0x7ca
  testing.(*M).Run()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1504 +0x9d1
  main.main()
      _testmain.go:303 +0x32b

Goroutine 57 (running) created at:
  github.com/cilium/cilium/pkg/hubble/container.TestRingReader_NextFollow_WithEmptyRing()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader_test.go:292 +0x576
  testing.tRunner()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1306 +0x47
==================
==================
WARNING: DATA RACE
Write at 0x00c0000958e0 by goroutine 52:
  github.com/cilium/cilium/pkg/hubble/container.(*RingReader).NextFollow.func1()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader.go:86 +0x10e
  github.com/cilium/cilium/pkg/hubble/container.(*RingReader).NextFollow·dwrap·1()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader.go:89 +0x58

Previous read at 0x00c0000958e0 by goroutine 57:
  github.com/cilium/cilium/pkg/hubble/container.(*RingReader).NextFollow()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader.go:99 +0x40e
  github.com/cilium/cilium/pkg/hubble/container.TestRingReader_NextFollow_WithEmptyRing.func1()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader_test.go:295 +0x84

Goroutine 52 (running) created at:
  github.com/cilium/cilium/pkg/hubble/container.(*RingReader).NextFollow()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader.go:82 +0x2f8
  github.com/cilium/cilium/pkg/hubble/container.TestRingReader_NextFollow_WithEmptyRing.func1()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader_test.go:295 +0x84

Goroutine 57 (finished) created at:
  github.com/cilium/cilium/pkg/hubble/container.TestRingReader_NextFollow_WithEmptyRing()
      /home/travis/gopath/src/github.com/cilium/cilium/pkg/hubble/container/ring_reader_test.go:292 +0x576
  testing.tRunner()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /home/travis/.gimme/versions/go1.17.linux.amd64/src/testing/testing.go:1306 +0x47
==================
    testing.go:1152: race detected during execution of test
--- FAIL: TestRingReader_NextFollow_WithEmptyRing (0.10s)