chain/neutrino: fix deadlock

chain/neutrino.go

@@ -201,7 +201,6 @@ func (s *NeutrinoClient) Rescan(startHash *chainhash.Hash, addrs []btcutil.Addre
 	// notification indicating the rescan has "finished".
 	if header.BlockHash() == *startHash {
 		s.finished = true
-		s.clientMtx.Unlock()
 		select {
 		case s.enqueueNotification <- &RescanFinished{
 			Hash:   startHash,
@@ -213,7 +212,6 @@ func (s *NeutrinoClient) Rescan(startHash *chainhash.Hash, addrs []btcutil.Addre
 		case <-s.rescanQuit:
 			return nil
 		}
-		s.clientMtx.Lock()
 	}
 
 	s.rescan = s.CS.NewRescan(
@@ -249,11 +247,11 @@ func (s *NeutrinoClient) NotifyBlocks() error {
 // NotifyReceived replicates the RPC client's NotifyReceived command.
 func (s *NeutrinoClient) NotifyReceived(addrs []btcutil.Address) error {
 	s.clientMtx.Lock()
-	defer s.clientMtx.Unlock()
 
 	// If we have a rescan running, we just need to add the appropriate
 	// addresses to the watch list.
 	if s.scanning {
+		s.clientMtx.Unlock()
 		return s.rescan.Update(neutrino.AddAddrs(addrs...))
 	}
 
@@ -276,6 +274,7 @@ func (s *NeutrinoClient) NotifyReceived(addrs []btcutil.Address) error {
 		neutrino.WatchAddrs(addrs...),
 	)
 	s.rescanErr = s.rescan.Start()
+	s.clientMtx.Unlock()
 	return nil
 }