From 853d5d3fd0a3cb7e9e6cf05da147379cfb132804 Mon Sep 17 00:00:00 2001
From: Evgeny Danienko <6655321@bk.ru>
Date: Tue, 24 Oct 2017 14:39:36 +0300
Subject: [PATCH] les: wg data race fixed

---
 les/fetcher.go | 11 ++++++++---
 les/handler.go | 12 +++++++++++-
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/les/fetcher.go b/les/fetcher.go
index 4fc142f0f4..e0d1465b0e 100644
--- a/les/fetcher.go
+++ b/les/fetcher.go
@@ -20,6 +20,7 @@ package les
 import (
 	"math/big"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -123,11 +124,15 @@ func newLightFetcher(pm *ProtocolManager) *lightFetcher {
 
 // syncLoop is the main event loop of the light fetcher
 func (f *lightFetcher) syncLoop() {
-	f.pm.wg.Add(1)
-	defer f.pm.wg.Done()
-
+	once := true
 	requesting := false
 	for {
+		if once && atomic.LoadInt32(f.pm.isClosed) != closed {
+			once = false
+			f.pm.wg.Add(1)
+			defer f.pm.wg.Done()
+		}
+
 		select {
 		case <-f.pm.quitSync:
 			return
diff --git a/les/handler.go b/les/handler.go
index df7eb6af51..285d2aeecf 100644
--- a/les/handler.go
+++ b/les/handler.go
@@ -24,6 +24,7 @@ import (
 	"math/big"
 	"net"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -115,6 +116,7 @@ type ProtocolManager struct {
 
 	// channels for fetcher, syncer, txsyncLoop
 	newPeerCh   chan *peer
+	isClosed	*int32
 	quitSync    chan struct{}
 	noMorePeers chan struct{}
 
@@ -123,10 +125,16 @@ type ProtocolManager struct {
 	wg *sync.WaitGroup
 }
 
+const (
+	started int32 = iota
+	closed
+)
+
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
 func NewProtocolManager(chainConfig *params.ChainConfig, lightSync bool, networkId uint64, mux *event.TypeMux, engine consensus.Engine, peers *peerSet, blockchain BlockChain, txpool txPool, chainDb ethdb.Database, odr *LesOdr, txrelay *LesTxRelay, quitSync chan struct{}, wg *sync.WaitGroup) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
+	isClosed := started
 	manager := &ProtocolManager{
 		lightSync:   lightSync,
 		eventMux:    mux,
@@ -139,6 +147,7 @@ func NewProtocolManager(chainConfig *params.ChainConfig, lightSync bool, network
 		txrelay:     txrelay,
 		peers:       peers,
 		newPeerCh:   make(chan *peer),
+		isClosed:    &isClosed,
 		quitSync:    quitSync,
 		wg:          wg,
 		noMorePeers: make(chan struct{}),
@@ -242,7 +251,8 @@ func (pm *ProtocolManager) Stop() {
 	// will exit when they try to register.
 	pm.peers.Close()
 
-	// Wait for any process action
+	// Wait for any process action. Wait should be executed after all pm.wg.Add()
+	atomic.StoreInt32(pm.isClosed, closed)
 	pm.wg.Wait()
 
 	log.Info("Light Ethereum protocol stopped")