Another data race in LES

[AlekSi]

Seems similar to #16610, but different.

Tagged Geth v1.8.10, built with Go 1.10.2 on macOS 10.13.5 with race detector enabled.

$ geth --syncmode=light --metrics --rpc --rpcapi=debug,net,eth

[…]

==================
WARNING: DATA RACE
Write at 0x00c43fd2c0a0 by goroutine 4619:
  github.com/ethereum/go-ethereum/les.(*ChtRequest).Validate()
      /XXX/src/github.com/ethereum/go-ethereum/les/odr_requests.go:457 +0x987
  github.com/ethereum/go-ethereum/les.(*LesOdr).Retrieve.func4()
      /XXX/src/github.com/ethereum/go-ethereum/les/odr.go:111 +0x90
  github.com/ethereum/go-ethereum/les.(*sentReq).deliver()
      /XXX/src/github.com/ethereum/go-ethereum/les/retrieve.go:366 +0x26e
  github.com/ethereum/go-ethereum/les.(*retrieveManager).deliver()
      /XXX/src/github.com/ethereum/go-ethereum/les/retrieve.go:172 +0x131
  github.com/ethereum/go-ethereum/les.(*ProtocolManager).handleMsg()
      /XXX/src/github.com/ethereum/go-ethereum/les/handler.go:1097 +0xc94
  github.com/ethereum/go-ethereum/les.(*ProtocolManager).handle()
      /XXX/src/github.com/ethereum/go-ethereum/les/handler.go:327 +0x837
  github.com/ethereum/go-ethereum/les.NewProtocolManager.func1()
      /XXX/src/github.com/ethereum/go-ethereum/les/handler.go:175 +0x325
  github.com/ethereum/go-ethereum/p2p.(*Peer).startProtocols.func1()
      /XXX/src/github.com/ethereum/go-ethereum/p2p/peer.go:348 +0x8b

Previous read at 0x00c43fd2c0a0 by goroutine 1256:
  github.com/ethereum/go-ethereum/light.GetHeaderByNumber()
      /XXX/src/github.com/ethereum/go-ethereum/light/odr_util.go:69 +0x3d7
  github.com/ethereum/go-ethereum/light.(*LightChain).GetHeaderByNumberOdr()
      /XXX/src/github.com/ethereum/go-ethereum/light/lightchain.go:448 +0xe1
  github.com/ethereum/go-ethereum/les.(*LesApiBackend).HeaderByNumber()
      /XXX/src/github.com/ethereum/go-ethereum/les/api_backend.go:64 +0x104
  github.com/ethereum/go-ethereum/eth/filters.(*Filter).indexedLogs()
      /XXX/src/github.com/ethereum/go-ethereum/eth/filters/filter.go:164 +0x386
  github.com/ethereum/go-ethereum/eth/filters.(*Filter).Logs()
      /XXX/src/github.com/ethereum/go-ethereum/eth/filters/filter.go:122 +0x4ca
  github.com/ethereum/go-ethereum/eth/filters.(*PublicFilterAPI).GetFilterLogs()
      /XXX/src/github.com/ethereum/go-ethereum/eth/filters/api.go:385 +0x2fd
  runtime.call128()
      /usr/local/Cellar/go/1.10.2/libexec/src/runtime/asm_amd64.s:575 +0x51
  reflect.Value.Call()
      /usr/local/Cellar/go/1.10.2/libexec/src/reflect/value.go:308 +0xc0
  github.com/ethereum/go-ethereum/rpc.(*Server).handle()
      /XXX/src/github.com/ethereum/go-ethereum/rpc/server.go:312 +0x1178
  github.com/ethereum/go-ethereum/rpc.(*Server).exec()
      /XXX/src/github.com/ethereum/go-ethereum/rpc/server.go:334 +0x24b
  github.com/ethereum/go-ethereum/rpc.(*Server).serveRequest.func2()
      /XXX/src/github.com/ethereum/go-ethereum/rpc/server.go:207 +0x151

Goroutine 4619 (running) created at:
  github.com/ethereum/go-ethereum/p2p.(*Peer).startProtocols()
      /XXX/src/github.com/ethereum/go-ethereum/p2p/peer.go:347 +0x2ed
  github.com/ethereum/go-ethereum/p2p.(*Peer).run()
      /XXX/src/github.com/ethereum/go-ethereum/p2p/peer.go:197 +0x164
  github.com/ethereum/go-ethereum/p2p.(*Server).runPeer()
      /XXX/src/github.com/ethereum/go-ethereum/p2p/server.go:894 +0x211

Goroutine 1256 (running) created at:
  github.com/ethereum/go-ethereum/rpc.(*Server).serveRequest()
      /XXX/src/github.com/ethereum/go-ethereum/rpc/server.go:202 +0x384
  github.com/ethereum/go-ethereum/rpc.(*Server).ServeCodec()
      /XXX/src/github.com/ethereum/go-ethereum/rpc/server.go:219 +0xb1
==================

[AlekSi]

/cc @ligi @zsfelfoldi

[rjl493456442]

I think this issue has been fixed in #16776