From 6209545083f656f2dccbe4561644a757ff6443b5 Mon Sep 17 00:00:00 2001
From: Andrey Petrov <andrey.petrov@shazow.net>
Date: Thu, 7 Jun 2018 21:50:08 -0400
Subject: p2p: Wrap conn.flags ops with atomic.Load/Store

---
 p2p/peer.go        | 26 ++++++++++++--------------
 p2p/server.go      | 20 ++++++++++++++++----
 p2p/server_test.go |  2 --
 3 files changed, 28 insertions(+), 20 deletions(-)

(limited to 'p2p')

diff --git a/p2p/peer.go b/p2p/peer.go
index ff8602602..c4c1fcd7c 100644
--- a/p2p/peer.go
+++ b/p2p/peer.go
@@ -95,11 +95,10 @@ type PeerEvent struct {
 
 // Peer represents a connected remote node.
 type Peer struct {
-	rw        *conn
-	isInbound bool // Cached from rw.flags to avoid a race condition
-	running   map[string]*protoRW
-	log       log.Logger
-	created   mclock.AbsTime
+	rw      *conn
+	running map[string]*protoRW
+	log     log.Logger
+	created mclock.AbsTime
 
 	wg       sync.WaitGroup
 	protoErr chan error
@@ -161,20 +160,19 @@ func (p *Peer) String() string {
 
 // Inbound returns true if the peer is an inbound connection
 func (p *Peer) Inbound() bool {
-	return p.isInbound
+	return p.rw.is(inboundConn)
 }
 
 func newPeer(conn *conn, protocols []Protocol) *Peer {
 	protomap := matchProtocols(protocols, conn.caps, conn)
 	p := &Peer{
-		rw:        conn,
-		isInbound: conn.is(inboundConn),
-		running:   protomap,
-		created:   mclock.Now(),
-		disc:      make(chan DiscReason),
-		protoErr:  make(chan error, len(protomap)+1), // protocols + pingLoop
-		closed:    make(chan struct{}),
-		log:       log.New("id", conn.id, "conn", conn.flags),
+		rw:       conn,
+		running:  protomap,
+		created:  mclock.Now(),
+		disc:     make(chan DiscReason),
+		protoErr: make(chan error, len(protomap)+1), // protocols + pingLoop
+		closed:   make(chan struct{}),
+		log:      log.New("id", conn.id, "conn", conn.flags),
 	}
 	return p
 }
diff --git a/p2p/server.go b/p2p/server.go
index 39ff2f51e..d2cb94925 100644
--- a/p2p/server.go
+++ b/p2p/server.go
@@ -23,6 +23,7 @@ import (
 	"fmt"
 	"net"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -187,7 +188,7 @@ type peerDrop struct {
 	requested bool // true if signaled by the peer
 }
 
-type connFlag int
+type connFlag int32
 
 const (
 	dynDialedConn connFlag = 1 << iota
@@ -252,7 +253,18 @@ func (f connFlag) String() string {
 }
 
 func (c *conn) is(f connFlag) bool {
-	return c.flags&f != 0
+	flags := connFlag(atomic.LoadInt32((*int32)(&c.flags)))
+	return flags&f != 0
+}
+
+func (c *conn) set(f connFlag, val bool) {
+	flags := connFlag(atomic.LoadInt32((*int32)(&c.flags)))
+	if val {
+		flags |= f
+	} else {
+		flags &= ^f
+	}
+	atomic.StoreInt32((*int32)(&c.flags), int32(flags))
 }
 
 // Peers returns all connected peers.
@@ -632,7 +644,7 @@ running:
 			trusted[n.ID] = true
 			// Mark any already-connected peer as trusted
 			if p, ok := peers[n.ID]; ok {
-				p.rw.flags |= trustedConn
+				p.rw.set(trustedConn, true)
 			}
 		case n := <-srv.removetrusted:
 			// This channel is used by RemoveTrustedPeer to remove an enode
@@ -643,7 +655,7 @@ running:
 			}
 			// Unmark any already-connected peer as trusted
 			if p, ok := peers[n.ID]; ok {
-				p.rw.flags &= ^trustedConn
+				p.rw.set(trustedConn, false)
 			}
 		case op := <-srv.peerOp:
 			// This channel is used by Peers and PeerCount.
diff --git a/p2p/server_test.go b/p2p/server_test.go
index 65897e018..3f24a79ba 100644
--- a/p2p/server_test.go
+++ b/p2p/server_test.go
@@ -189,12 +189,10 @@ func TestServerDial(t *testing.T) {
 				}
 				done <- true
 			}()
-
 			// Trigger potential race conditions
 			peer = srv.Peers()[0]
 			_ = peer.Inbound()
 			_ = peer.Info()
-
 			<-done
 		case <-time.After(1 * time.Second):
 			t.Error("server did not launch peer within one second")
-- 
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