perf grinding at the extremes

- removed defer/recover/panic where warranted
- found and eliminated race conditions when extremely high connection pressure was hit
- resolved race condition in blossomsub around mesh maintenance
- incorporated resource manager scaling to work off low/hi watermark values

go-libp2p-blossomsub/backoff_test.go

@@ -23,9 +23,11 @@ func TestBackoff_Update(t *testing.T) {
 
 	b := newBackoff(ctx, size, cleanupInterval, maxBackoffAttempts)
 
+	b.mu.Lock()
 	if len(b.info) > 0 {
 		t.Fatal("non-empty info map for backoff")
 	}
+	b.mu.Unlock()
 
 	if d, err := b.updateAndGet(id1); d != time.Duration(0) || err != nil {
 		t.Fatalf("invalid initialization: %v, \t, %s", d, err)
@@ -64,9 +66,11 @@ func TestBackoff_Update(t *testing.T) {
 		t.Fatalf("invalid backoff result, expected: %v, got: %v", MinBackoffDelay, got)
 	}
 
+	b.mu.Lock()
 	// sets last tried of id2 to long ago that it resets back upon next try.
 	// update attempts on id2 are below threshold, hence peer should never go beyond backoff attempt threshold.
 	b.info[id2].lastTried = time.Now().Add(-TimeToLive)
+	b.mu.Unlock()
 	got, err = b.updateAndGet(id2)
 	if err != nil {
 		t.Fatalf("unexpected error post update: %s", err)
@@ -75,10 +79,11 @@ func TestBackoff_Update(t *testing.T) {
 		t.Fatalf("invalid ttl expiration, expected: %v, got: %v", time.Duration(0), got)
 	}
 
+	b.mu.Lock()
 	if len(b.info) != 2 {
 		t.Fatalf("pre-invalidation attempt, info map size mismatch, expected: %d, got: %d", 2, len(b.info))
 	}
-
+	b.mu.Unlock()
 }
 
 func TestBackoff_Clean(t *testing.T) {
@@ -96,12 +101,16 @@ func TestBackoff_Clean(t *testing.T) {
 		if err != nil {
 			t.Fatalf("unexpected error post update: %s", err)
 		}
+		b.mu.Lock()
 		b.info[id].lastTried = time.Now().Add(-TimeToLive) // enforces expiry
+		b.mu.Unlock()
 	}
 
+	b.mu.Lock()
 	if len(b.info) != size {
 		t.Fatalf("info map size mismatch, expected: %d, got: %d", size, len(b.info))
 	}
+	b.mu.Unlock()
 
 	// waits for a cleanup loop to kick-in
 	time.Sleep(2 * cleanupInterval)
@@ -115,8 +124,10 @@ func TestBackoff_Clean(t *testing.T) {
 		t.Fatalf("invalid backoff result, expected: %v, got: %v", time.Duration(0), got)
 	}
 
+	b.mu.Lock()
 	// except "some-new-peer" every other records must be cleaned up
 	if len(b.info) != 1 {
 		t.Fatalf("info map size mismatch, expected: %d, got: %d", 1, len(b.info))
 	}
+	b.mu.Unlock()
 }

go-libp2p-blossomsub/blossomsub.go

@@ -8,6 +8,7 @@ import (
 	"math/rand"
 	"slices"
 	"sort"
+	"sync"
 	"time"
 
 	pb "source.quilibrium.com/quilibrium/monorepo/go-libp2p-blossomsub/pb"
@@ -451,6 +452,7 @@ type BlossomSubRouter struct {
 	backoff  map[string]map[peer.ID]time.Time // prune backoff
 	connect  chan connectInfo                 // px connection requests
 	cab      peerstore.AddrBook
+	meshMx   sync.RWMutex
 
 	protos  []protocol.ID
 	feature BlossomSubFeatureTest
@@ -625,9 +627,11 @@ func (bs *BlossomSubRouter) RemovePeer(p peer.ID) {
 	log.Debugf("PEERDOWN: Remove disconnected peer %s", p)
 	bs.tracer.RemovePeer(p)
 	delete(bs.peers, p)
+	bs.meshMx.Lock()
 	for _, peers := range bs.mesh {
 		delete(peers, p)
 	}
+	bs.meshMx.Unlock()
 	for _, peers := range bs.fanout {
 		delete(peers, p)
 	}
@@ -651,8 +655,10 @@ func (bs *BlossomSubRouter) EnoughPeers(bitmask []byte, suggested int) bool {
 		}
 	}
 
+	bs.meshMx.RLock()
 	// BlossomSub peers
 	bsPeers = len(bs.mesh[string(bitmask)])
+	bs.meshMx.RUnlock()
 
 	if suggested == 0 {
 		suggested = bs.params.Dlo
@@ -724,7 +730,9 @@ func (bs *BlossomSubRouter) handleIHave(p peer.ID, ctl *pb.ControlMessage) []*pb
 	iwant := make(map[string]struct{})
 	for _, ihave := range ctl.GetIhave() {
 		bitmask := ihave.GetBitmask()
+		bs.meshMx.RLock()
 		_, ok := bs.mesh[string(bitmask)]
+		bs.meshMx.RUnlock()
 		if !ok {
 			continue
 		}
@@ -830,7 +838,9 @@ func (bs *BlossomSubRouter) handleGraft(p peer.ID, ctl *pb.ControlMessage) []*pb
 			continue
 		}
 
+		bs.meshMx.RLock()
 		peers, ok := bs.mesh[string(bitmask)]
+		bs.meshMx.RUnlock()
 		if !ok {
 			// don't do PX when there is an unknown bitmask to avoid leaking our peers
 			doPX = false
@@ -919,7 +929,9 @@ func (bs *BlossomSubRouter) handlePrune(p peer.ID, ctl *pb.ControlMessage) {
 
 	for _, prune := range ctl.GetPrune() {
 		bitmask := prune.GetBitmask()
+		bs.meshMx.RLock()
 		peers, ok := bs.mesh[string(bitmask)]
+		bs.meshMx.RUnlock()
 		if !ok {
 			continue
 		}
@@ -1101,7 +1113,9 @@ func (bs *BlossomSubRouter) Publish(msg *Message) {
 			}
 
 			// BlossomSub peers
+			bs.meshMx.RLock()
 			gmap, ok := bs.mesh[string(bitmask)]
+			bs.meshMx.RUnlock()
 			if !ok {
 				// we are not in the mesh for bitmask, use fanout peers
 				gmap, ok = bs.fanout[string(bitmask)]
@@ -1137,7 +1151,9 @@ func (bs *BlossomSubRouter) Publish(msg *Message) {
 }
 
 func (bs *BlossomSubRouter) Join(bitmask []byte) {
+	bs.meshMx.RLock()
 	gmap, ok := bs.mesh[string(bitmask)]
+	bs.meshMx.RUnlock()
 	if ok {
 		return
 	}
@@ -1172,7 +1188,9 @@ func (bs *BlossomSubRouter) Join(bitmask []byte) {
 			}
 		}
 
+		bs.meshMx.Lock()
 		bs.mesh[string(bitmask)] = gmap
+		bs.meshMx.Unlock()
 		delete(bs.fanout, string(bitmask))
 		delete(bs.lastpub, string(bitmask))
 	} else {
@@ -1184,7 +1202,9 @@ func (bs *BlossomSubRouter) Join(bitmask []byte) {
 			return !direct && !doBackOff && bs.score.Score(p) >= 0
 		})
 		gmap = peerListToMap(peers)
+		bs.meshMx.Lock()
 		bs.mesh[string(bitmask)] = gmap
+		bs.meshMx.Unlock()
 	}
 
 	for p := range gmap {
@@ -1195,7 +1215,9 @@ func (bs *BlossomSubRouter) Join(bitmask []byte) {
 }
 
 func (bs *BlossomSubRouter) Leave(bitmask []byte) {
+	bs.meshMx.RLock()
 	gmap, ok := bs.mesh[string(bitmask)]
+	bs.meshMx.RUnlock()
 	if !ok {
 		return
 	}
@@ -1203,7 +1225,9 @@ func (bs *BlossomSubRouter) Leave(bitmask []byte) {
 	log.Debugf("LEAVE %s", bitmask)
 	bs.tracer.Leave(bitmask)
 
+	bs.meshMx.Lock()
 	delete(bs.mesh, string(bitmask))
+	bs.meshMx.Unlock()
 
 	for p := range gmap {
 		log.Debugf("LEAVE: Remove mesh link to %s in %s", p, bitmask)
@@ -1252,7 +1276,9 @@ func (bs *BlossomSubRouter) sendRPC(p peer.ID, out *RPC) {
 		delete(bs.gossip, p)
 	}
 
+	bs.p.peersMx.RLock()
 	mch, ok := bs.p.peers[p]
+	bs.p.peersMx.RUnlock()
 	if !ok {
 		return
 	}
@@ -1485,6 +1511,7 @@ func (bs *BlossomSubRouter) heartbeat() {
 	}
 
 	// maintain the mesh for bitmasks we have joined
+	bs.meshMx.Lock()
 	for bitmask, peers := range bs.mesh {
 		bitmask := []byte(bitmask)
 		prunePeer := func(p peer.ID) {
@@ -1667,6 +1694,7 @@ func (bs *BlossomSubRouter) heartbeat() {
 			}
 		}
 	}
+	bs.meshMx.Unlock()
 
 	// expire fanout for bitmasks we haven't published to in a while
 	now := time.Now().UnixNano()
@@ -1921,7 +1949,9 @@ func (bs *BlossomSubRouter) piggybackControl(p peer.ID, out *RPC, ctl *pb.Contro
 
 	for _, graft := range ctl.GetGraft() {
 		bitmask := graft.GetBitmask()
+		bs.meshMx.RLock()
 		peers, ok := bs.mesh[string(bitmask)]
+		bs.meshMx.RUnlock()
 		if !ok {
 			continue
 		}
@@ -1933,7 +1963,9 @@ func (bs *BlossomSubRouter) piggybackControl(p peer.ID, out *RPC, ctl *pb.Contro
 
 	for _, prune := range ctl.GetPrune() {
 		bitmask := prune.GetBitmask()
+		bs.meshMx.RLock()
 		peers, ok := bs.mesh[string(bitmask)]
+		bs.meshMx.RUnlock()
 		if !ok {
 			toprune = append(toprune, prune)
 			continue

go-libp2p-blossomsub/blossomsub_spam_test.go

@@ -65,7 +65,7 @@ func TestBlossomSubAttackSpamIWANT(t *testing.T) {
 		data := make([]byte, 16)
 		rand.Read(data)
 
-		if err = bitmasks[0].Publish(ctx, bitmasks[0].bitmask, data); err != nil {
+		if err := bitmasks[0].Publish(ctx, bitmasks[0].bitmask, data); err != nil {
 			t.Fatal(err)
 		}
 	}
@@ -676,6 +676,7 @@ func TestBlossomSubAttackInvalidMessageSpam(t *testing.T) {
 	ps, err := NewBlossomSub(ctx, legit,
 		WithEventTracer(tracer),
 		WithPeerScore(params, thresholds),
+		WithMessageSignaturePolicy(StrictSign),
 	)
 	if err != nil {
 		t.Fatal(err)

go-libp2p-blossomsub/blossomsub_test.go

@@ -2257,7 +2257,9 @@ func TestBlossomSubJoinBitmask(t *testing.T) {
 
 	time.Sleep(time.Second)
 
+	router0.meshMx.RLock()
 	meshMap := router0.mesh[string([]byte{0x00, 0x00, 0x80, 0x00})]
+	router0.meshMx.RUnlock()
 	if len(meshMap) != 1 {
 		t.Fatalf("Unexpect peer included in the mesh")
 	}
@@ -2820,14 +2822,14 @@ func TestBloomRouting(t *testing.T) {
 			// Normally the expectation is that any subscription will do when using a bloom bitmask
 			// But we need to verify one gets it.
 			g := sync.WaitGroup{}
-			g.Add(len(sub))
+			g.Add(len(sub) + 1)
 			errch := make(chan error)
 			var errs []error
 			for _, s := range sub {
 				s := s
 				go func() {
 					defer g.Done()
-					nctx, _ := context.WithDeadline(ctx, time.Now().Add(10*time.Millisecond))
+					nctx, _ := context.WithDeadline(ctx, time.Now().Add(100*time.Millisecond))
 					got, err := s.Next(nctx)
 					if err != nil {
 						errch <- err
@@ -2842,7 +2844,7 @@ func TestBloomRouting(t *testing.T) {
 			}
 
 			go func() {
-				for i := 0; i < len(sub); i++ {
+				for _ = range sub {
 					select {
 					case err := <-errch:
 						if err != nil {
@@ -2850,6 +2852,7 @@ func TestBloomRouting(t *testing.T) {
 						}
 					}
 				}
+				g.Done()
 			}()
 			g.Wait()
 			if len(errs) == len(sub) {
@@ -2919,6 +2922,7 @@ func TestBloomPropagationOverSubTreeTopology(t *testing.T) {
 		}
 
 		for _, subs := range chs {
+			subs := subs
 			g := sync.WaitGroup{}
 			g.Add(len(subs))
 			nctx, cancel := context.WithCancel(ctx)
@@ -3141,6 +3145,7 @@ func containsBitmask(bitmask []byte, slice []byte) bool {
 
 func assertReceivedBitmaskSubgroup(t *testing.T, ctx context.Context, subs [][]*Subscription, msg []byte) {
 	for i, subs := range subs {
+		subs := subs
 		g := sync.WaitGroup{}
 		g.Add(len(subs))
 		nctx, cancel := context.WithCancel(ctx)
@@ -3148,7 +3153,7 @@ func assertReceivedBitmaskSubgroup(t *testing.T, ctx context.Context, subs [][]*
 		for _, s := range subs {
 			s := s
 			go func() {
-				nctx, _ := context.WithDeadline(nctx, time.Now().Add(10*time.Millisecond))
+				nctx, _ := context.WithDeadline(nctx, time.Now().Add(100*time.Millisecond))
 				got, err := s.Next(nctx)
 				if err != nil {
 					g.Done()

go-libp2p-blossomsub/pubsub.go

@@ -150,7 +150,8 @@ type PubSub struct {
 	blacklist     Blacklist
 	blacklistPeer chan peer.ID
 
-	peers map[peer.ID]chan *RPC
+	peers   map[peer.ID]chan *RPC
+	peersMx sync.RWMutex
 
 	inboundStreamsMx sync.Mutex
 	inboundStreams   map[peer.ID]network.Stream
@@ -565,11 +566,13 @@ func WithAppSpecificRpcInspector(inspector func(peer.ID, *RPC) error) Option {
 // processLoop handles all inputs arriving on the channels
 func (p *PubSub) processLoop(ctx context.Context) {
 	defer func() {
+		p.peersMx.Lock()
 		// Clean up go routines.
 		for _, ch := range p.peers {
 			close(ch)
 		}
 		p.peers = nil
+		p.peersMx.Unlock()
 		p.bitmasks = nil
 		p.seenMessages.Done()
 	}()
@@ -582,7 +585,9 @@ func (p *PubSub) processLoop(ctx context.Context) {
 		case s := <-p.newPeerStream:
 			pid := s.Conn().RemotePeer()
 
+			p.peersMx.RLock()
 			ch, ok := p.peers[pid]
+			p.peersMx.RUnlock()
 			if !ok {
 				log.Warn("new stream for unknown peer: ", pid)
 				s.Reset()
@@ -592,7 +597,9 @@ func (p *PubSub) processLoop(ctx context.Context) {
 			if p.blacklist.Contains(pid) {
 				log.Warn("closing stream for blacklisted peer: ", pid)
 				close(ch)
+				p.peersMx.Lock()
 				delete(p.peers, pid)
+				p.peersMx.Unlock()
 				s.Reset()
 				continue
 			}
@@ -600,7 +607,9 @@ func (p *PubSub) processLoop(ctx context.Context) {
 			p.rt.AddPeer(pid, s.Protocol())
 
 		case pid := <-p.newPeerError:
+			p.peersMx.Lock()
 			delete(p.peers, pid)
+			p.peersMx.Unlock()
 
 		case <-p.peerDead:
 			p.handleDeadPeers()
@@ -650,10 +659,14 @@ func (p *PubSub) processLoop(ctx context.Context) {
 			log.Infof("Blacklisting peer %s", pid)
 			p.blacklist.Add(pid)
 
+			p.peersMx.RLock()
 			ch, ok := p.peers[pid]
+			p.peersMx.RUnlock()
 			if ok {
 				close(ch)
+				p.peersMx.Lock()
 				delete(p.peers, pid)
+				p.peersMx.Unlock()
 				for t, tmap := range p.bitmasks {
 					if _, ok := tmap[pid]; ok {
 						delete(tmap, pid)
@@ -682,6 +695,7 @@ peerloop:
 		}
 
 		var peerset []peer.ID
+		p.peersMx.RLock()
 		for p := range p.peers {
 			_, ok := tmap[p]
 			if !ok {
@@ -689,6 +703,7 @@ peerloop:
 			}
 			peerset = append(peerset, p)
 		}
+		p.peersMx.RUnlock()
 
 		if len(peers) == 0 {
 			peers = peerset
@@ -728,10 +743,13 @@ func (p *PubSub) handlePendingPeers() {
 			continue
 		}
 
+		p.peersMx.RLock()
 		if _, ok := p.peers[pid]; ok {
+			p.peersMx.RUnlock()
 			log.Debug("already have connection to peer: ", pid)
 			continue
 		}
+		p.peersMx.RUnlock()
 
 		if p.blacklist.Contains(pid) {
 			log.Warn("ignoring connection from blacklisted peer: ", pid)
@@ -741,7 +759,9 @@ func (p *PubSub) handlePendingPeers() {
 		messages := make(chan *RPC, p.peerOutboundQueueSize)
 		messages <- p.getHelloPacket()
 		go p.handleNewPeer(p.ctx, pid, messages)
+		p.peersMx.Lock()
 		p.peers[pid] = messages
+		p.peersMx.Unlock()
 	}
 }
 
@@ -758,13 +778,17 @@ func (p *PubSub) handleDeadPeers() {
 	p.peerDeadPrioLk.Unlock()
 
 	for pid := range deadPeers {
+		p.peersMx.RLock()
 		ch, ok := p.peers[pid]
+		p.peersMx.RUnlock()
 		if !ok {
 			continue
 		}
 
 		close(ch)
+		p.peersMx.Lock()
 		delete(p.peers, pid)
+		p.peersMx.Unlock()
 
 		for t, tmap := range p.bitmasks {
 			if _, ok := tmap[pid]; ok {
@@ -787,7 +811,9 @@ func (p *PubSub) handleDeadPeers() {
 			log.Debugf("peer declared dead but still connected; respawning writer: %s", pid)
 			messages := make(chan *RPC, p.peerOutboundQueueSize)
 			messages <- p.getHelloPacket()
+			p.peersMx.Lock()
 			p.peers[pid] = messages
+			p.peersMx.Unlock()
 			go p.handleNewPeerWithBackoff(p.ctx, pid, backoffDelay, messages)
 		}
 	}
@@ -951,6 +977,7 @@ func (p *PubSub) announce(bitmask []byte, sub bool) {
 	}
 
 	out := rpcWithSubs(subopt)
+	p.peersMx.RLock()
 	for pid, peer := range p.peers {
 		select {
 		case peer <- out:
@@ -961,6 +988,7 @@ func (p *PubSub) announce(bitmask []byte, sub bool) {
 			go p.announceRetry(pid, bitmask, sub)
 		}
 	}
+	p.peersMx.RUnlock()
 }
 
 func (p *PubSub) announceRetry(pid peer.ID, bitmask []byte, sub bool) {
@@ -984,7 +1012,9 @@ func (p *PubSub) announceRetry(pid peer.ID, bitmask []byte, sub bool) {
 }
 
 func (p *PubSub) doAnnounceRetry(pid peer.ID, bitmask []byte, sub bool) {
+	p.peersMx.RLock()
 	peer, ok := p.peers[pid]
+	p.peersMx.RUnlock()
 	if !ok {
 		return
 	}

go-libp2p/p2p/host/autonat/autonat.go

@@ -198,10 +198,10 @@ func (as *AmbientAutoNAT) background() {
 		// probe finished.
 		case err, ok := <-as.dialResponses:
 			if !ok {
-				close(as.backgroundRunning)
-				as.subscriber.Close()
-				as.emitReachabilityChanged.Close()
 				timer.Stop()
+				as.emitReachabilityChanged.Close()
+				as.subscriber.Close()
+				close(as.backgroundRunning)
 				return
 			}
 			if IsDialRefused(err) {
@@ -215,10 +215,10 @@ func (as *AmbientAutoNAT) background() {
 			timerRunning = false
 			retryProbe = false
 		case <-as.ctx.Done():
-			close(as.backgroundRunning)
-			as.subscriber.Close()
-			as.emitReachabilityChanged.Close()
 			timer.Stop()
+			as.emitReachabilityChanged.Close()
+			as.subscriber.Close()
+			close(as.backgroundRunning)
 			return
 		}
 

go-libp2p/p2p/host/basic/basic_host.go

@@ -563,8 +563,8 @@ func (h *BasicHost) background() {
 		case <-ticker.C:
 		case <-h.addrChangeChan:
 		case <-h.ctx.Done():
-			h.refCount.Done()
 			ticker.Stop()
+			h.refCount.Done()
 			return
 		}
 	}

go-libp2p/p2p/host/resource-manager/stats.go

@@ -177,9 +177,9 @@ func NewStatsTraceReporter() (StatsTraceReporter, error) {
 
 func (r StatsTraceReporter) ConsumeEvent(evt TraceEvt) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	r.consumeEventWithLabelSlice(evt, tags)
+	metricshelper.PutStringSlice(tags)
 }
 
 // Separate func so that we can test that this function does not allocate. The syncPool may allocate.

go-libp2p/p2p/host/resource-manager/trace.go

@@ -212,9 +212,9 @@ type TraceEvt struct {
 
 func (t *trace) push(evt TraceEvt) {
 	t.mx.Lock()
-	defer t.mx.Unlock()
 
 	if t.done {
+		t.mx.Unlock()
 		return
 	}
 	evt.Time = time.Now().Format(time.RFC3339Nano)
@@ -229,19 +229,13 @@ func (t *trace) push(evt TraceEvt) {
 	if t.path != "" {
 		t.pendingWrites = append(t.pendingWrites, evt)
 	}
+	t.mx.Unlock()
 }
 
 func (t *trace) backgroundWriter(out io.WriteCloser) {
-	defer t.wg.Done()
-	defer out.Close()
-
 	gzOut := gzip.NewWriter(out)
-	defer gzOut.Close()
-
 	jsonOut := json.NewEncoder(gzOut)
-
 	ticker := time.NewTicker(time.Second)
-	defer ticker.Stop()
 
 	var pend []interface{}
 
@@ -267,6 +261,11 @@ func (t *trace) backgroundWriter(out io.WriteCloser) {
 				t.mx.Lock()
 				t.done = true
 				t.mx.Unlock()
+
+				ticker.Stop()
+				gzOut.Close()
+				out.Close()
+				t.wg.Done()
 				return
 			}
 
@@ -275,6 +274,11 @@ func (t *trace) backgroundWriter(out io.WriteCloser) {
 				t.mx.Lock()
 				t.done = true
 				t.mx.Unlock()
+
+				ticker.Stop()
+				gzOut.Close()
+				out.Close()
+				t.wg.Done()
 				return
 			}
 
@@ -282,11 +286,19 @@ func (t *trace) backgroundWriter(out io.WriteCloser) {
 			getEvents()
 
 			if len(pend) == 0 {
+				ticker.Stop()
+				gzOut.Close()
+				out.Close()
+				t.wg.Done()
 				return
 			}
 
 			if err := t.writeEvents(pend, jsonOut); err != nil {
 				log.Warnf("error writing rcmgr trace: %s", err)
+				ticker.Stop()
+				gzOut.Close()
+				out.Close()
+				t.wg.Done()
 				return
 			}
 
@@ -294,6 +306,10 @@ func (t *trace) backgroundWriter(out io.WriteCloser) {
 				log.Warnf("error flushing rcmgr trace: %s", err)
 			}
 
+			ticker.Stop()
+			gzOut.Close()
+			out.Close()
+			t.wg.Done()
 			return
 		}
 	}

go-libp2p/p2p/http/libp2phttp.go

@@ -306,13 +306,11 @@ func (h *Host) Serve() error {
 	h.httpTransportInit()
 
 	closedWaitingForListeners := false
-	defer func() {
+
+	if len(h.ListenAddrs) == 0 && h.StreamHost == nil {
 		if !closedWaitingForListeners {
 			close(h.httpTransport.waitingForListeners)
 		}
-	}()
-
-	if len(h.ListenAddrs) == 0 && h.StreamHost == nil {
 		return ErrNoListeners
 	}
 
@@ -329,6 +327,9 @@ func (h *Host) Serve() error {
 	if h.StreamHost != nil {
 		listener, err := streamHostListen(h.StreamHost)
 		if err != nil {
+			if !closedWaitingForListeners {
+				close(h.httpTransport.waitingForListeners)
+			}
 			return err
 		}
 		h.httpTransport.listeners = append(h.httpTransport.listeners, listener)
@@ -348,6 +349,9 @@ func (h *Host) Serve() error {
 	err := h.setupListeners(errCh)
 	if err != nil {
 		closeAllListeners()
+		if !closedWaitingForListeners {
+			close(h.httpTransport.waitingForListeners)
+		}
 		return err
 	}
 
@@ -356,6 +360,9 @@ func (h *Host) Serve() error {
 
 	if len(h.httpTransport.listeners) == 0 || len(h.httpTransport.listenAddrs) == 0 {
 		closeAllListeners()
+		if !closedWaitingForListeners {
+			close(h.httpTransport.waitingForListeners)
+		}
 		return ErrNoListeners
 	}
 
@@ -372,7 +379,9 @@ func (h *Host) Serve() error {
 		<-errCh
 	}
 	close(errCh)
-
+	if !closedWaitingForListeners {
+		close(h.httpTransport.waitingForListeners)
+	}
 	return err
 }
 
@@ -437,8 +446,9 @@ func (s *streamReadCloser) Close() error {
 func (rt *streamRoundTripper) GetPeerMetadata() (PeerMeta, error) {
 	ctx := context.Background()
 	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(WellKnownRequestTimeout))
-	defer cancel()
+	peerMeta, err := rt.httpHost.getAndStorePeerMetadata(ctx, rt, rt.server)
-	return rt.httpHost.getAndStorePeerMetadata(ctx, rt, rt.server)
+	cancel()
+	return peerMeta, err
 }
 
 // RoundTrip implements http.RoundTripper.
@@ -460,11 +470,11 @@ func (rt *streamRoundTripper) RoundTrip(r *http.Request) (*http.Response, error)
 	r.Header.Add("connection", "close")
 
 	go func() {
-		defer s.CloseWrite()
 		r.Write(s)
 		if r.Body != nil {
 			r.Body.Close()
 		}
+		s.CloseWrite()
 	}()
 
 	if deadline, ok := r.Context().Deadline(); ok {
@@ -511,12 +521,13 @@ func (rt *roundTripperForSpecificServer) GetPeerMetadata() (PeerMeta, error) {
 
 	ctx := context.Background()
 	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(WellKnownRequestTimeout))
-	defer cancel()
 	wk, err := rt.httpHost.getAndStorePeerMetadata(ctx, rt, rt.server)
 	if err == nil {
 		rt.cachedProtos = wk
+		cancel()
 		return wk, nil
 	}
+	cancel()
 	return wk, err
 }
 
@@ -579,14 +590,15 @@ func (rt *namespacedRoundTripper) RoundTrip(r *http.Request) (*http.Response, er
 func (h *Host) NamespaceRoundTripper(roundtripper http.RoundTripper, p protocol.ID, server peer.ID) (*namespacedRoundTripper, error) {
 	ctx := context.Background()
 	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(WellKnownRequestTimeout))
-	defer cancel()
 	protos, err := h.getAndStorePeerMetadata(ctx, roundtripper, server)
 	if err != nil {
+		cancel()
 		return &namespacedRoundTripper{}, err
 	}
 
 	v, ok := protos[p]
 	if !ok {
+		cancel()
 		return &namespacedRoundTripper{}, fmt.Errorf("no protocol %s for server %s", p, server)
 	}
 
@@ -598,9 +610,11 @@ func (h *Host) NamespaceRoundTripper(roundtripper http.RoundTripper, p protocol.
 
 	u, err := url.Parse(path)
 	if err != nil {
+		cancel()
 		return &namespacedRoundTripper{}, fmt.Errorf("invalid path %s for protocol %s for server %s", v.Path, p, server)
 	}
 
+	cancel()
 	return &namespacedRoundTripper{
 		RoundTripper:      roundtripper,
 		protocolPrefix:    u.Path,
@@ -866,9 +880,9 @@ func requestPeerMeta(ctx context.Context, roundtripper http.RoundTripper, wellKn
 	if err != nil {
 		return nil, err
 	}
-	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
 		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
 	}
 
@@ -878,9 +892,11 @@ func requestPeerMeta(ctx context.Context, roundtripper http.RoundTripper, wellKn
 		N: peerMetadataLimit,
 	}).Decode(&meta)
 	if err != nil {
+		resp.Body.Close()
 		return nil, err
 	}
 
+	resp.Body.Close()
 	return meta, nil
 }
 

go-libp2p/p2p/http/ping/ping.go

@@ -48,20 +48,23 @@ func SendPing(client http.Client) error {
 	if err != nil {
 		return err
 	}
-	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
 		return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
 	}
 
 	rBody := [pingSize]byte{}
 	_, err = io.ReadFull(resp.Body, rBody[:])
 	if err != nil {
+		resp.Body.Close()
 		return err
 	}
 
 	if !bytes.Equal(body[:], rBody[:]) {
+		resp.Body.Close()
 		return errors.New("ping body mismatch")
 	}
+	resp.Body.Close()
 	return nil
 }

go-libp2p/p2p/net/conngater/conngater.go

@@ -133,9 +133,8 @@ func (cg *BasicConnectionGater) BlockPeer(p peer.ID) error {
 	}
 
 	cg.Lock()
-	defer cg.Unlock()
 	cg.blockedPeers[p] = struct{}{}
-
+	cg.Unlock()
 	return nil
 }
 
@@ -150,23 +149,21 @@ func (cg *BasicConnectionGater) UnblockPeer(p peer.ID) error {
 	}
 
 	cg.Lock()
-	defer cg.Unlock()
 
 	delete(cg.blockedPeers, p)
-
+	cg.Unlock()
 	return nil
 }
 
 // ListBlockedPeers return a list of blocked peers
 func (cg *BasicConnectionGater) ListBlockedPeers() []peer.ID {
 	cg.RLock()
-	defer cg.RUnlock()
 
 	result := make([]peer.ID, 0, len(cg.blockedPeers))
 	for p := range cg.blockedPeers {
 		result = append(result, p)
 	}
-
+	cg.RUnlock()
 	return result
 }
 
@@ -182,10 +179,9 @@ func (cg *BasicConnectionGater) BlockAddr(ip net.IP) error {
 	}
 
 	cg.Lock()
-	defer cg.Unlock()
 
 	cg.blockedAddrs[ip.String()] = struct{}{}
-
+	cg.Unlock()
 	return nil
 }
 
@@ -200,24 +196,22 @@ func (cg *BasicConnectionGater) UnblockAddr(ip net.IP) error {
 	}
 
 	cg.Lock()
-	defer cg.Unlock()
 
 	delete(cg.blockedAddrs, ip.String())
-
+	cg.Unlock()
 	return nil
 }
 
 // ListBlockedAddrs return a list of blocked IP addresses
 func (cg *BasicConnectionGater) ListBlockedAddrs() []net.IP {
 	cg.RLock()
-	defer cg.RUnlock()
 
 	result := make([]net.IP, 0, len(cg.blockedAddrs))
 	for ipStr := range cg.blockedAddrs {
 		ip := net.ParseIP(ipStr)
 		result = append(result, ip)
 	}
-
+	cg.RUnlock()
 	return result
 }
 
@@ -233,10 +227,9 @@ func (cg *BasicConnectionGater) BlockSubnet(ipnet *net.IPNet) error {
 	}
 
 	cg.Lock()
-	defer cg.Unlock()
 
 	cg.blockedSubnets[ipnet.String()] = ipnet
-
+	cg.Unlock()
 	return nil
 }
 
@@ -251,23 +244,21 @@ func (cg *BasicConnectionGater) UnblockSubnet(ipnet *net.IPNet) error {
 	}
 
 	cg.Lock()
-	defer cg.Unlock()
 
 	delete(cg.blockedSubnets, ipnet.String())
-
+	cg.Unlock()
 	return nil
 }
 
 // ListBlockedSubnets return a list of blocked IP subnets
 func (cg *BasicConnectionGater) ListBlockedSubnets() []*net.IPNet {
 	cg.RLock()
-	defer cg.RUnlock()
 
 	result := make([]*net.IPNet, 0, len(cg.blockedSubnets))
 	for _, ipnet := range cg.blockedSubnets {
 		result = append(result, ipnet)
 	}
-
+	cg.RUnlock()
 	return result
 }
 
@@ -276,60 +267,66 @@ var _ connmgr.ConnectionGater = (*BasicConnectionGater)(nil)
 
 func (cg *BasicConnectionGater) InterceptPeerDial(p peer.ID) (allow bool) {
 	cg.RLock()
-	defer cg.RUnlock()
 
 	_, block := cg.blockedPeers[p]
+	cg.RUnlock()
 	return !block
 }
 
 func (cg *BasicConnectionGater) InterceptAddrDial(p peer.ID, a ma.Multiaddr) (allow bool) {
 	// we have already filtered blocked peers in InterceptPeerDial, so we just check the IP
 	cg.RLock()
-	defer cg.RUnlock()
 
 	ip, err := manet.ToIP(a)
 	if err != nil {
+		cg.RUnlock()
 		log.Warnf("error converting multiaddr to IP addr: %s", err)
 		return true
 	}
 
 	_, block := cg.blockedAddrs[ip.String()]
 	if block {
+		cg.RUnlock()
 		return false
 	}
 
 	for _, ipnet := range cg.blockedSubnets {
 		if ipnet.Contains(ip) {
+			cg.RUnlock()
 			return false
 		}
 	}
 
+	cg.RUnlock()
 	return true
 }
 
 func (cg *BasicConnectionGater) InterceptAccept(cma network.ConnMultiaddrs) (allow bool) {
 	cg.RLock()
-	defer cg.RUnlock()
 
 	a := cma.RemoteMultiaddr()
 
 	ip, err := manet.ToIP(a)
 	if err != nil {
+		cg.RUnlock()
 		log.Warnf("error converting multiaddr to IP addr: %s", err)
 		return true
 	}
 
 	_, block := cg.blockedAddrs[ip.String()]
 	if block {
+		cg.RUnlock()
 		return false
 	}
 
 	for _, ipnet := range cg.blockedSubnets {
 		if ipnet.Contains(ip) {
+			cg.RUnlock()
 			return false
 		}
 	}
 
+	cg.RUnlock()
 	return true
 }
 
@@ -341,9 +338,9 @@ func (cg *BasicConnectionGater) InterceptSecured(dir network.Direction, p peer.I
 
 	// we have already filtered addrs in InterceptAccept, so we just check the peer ID
 	cg.RLock()
-	defer cg.RUnlock()
 
 	_, block := cg.blockedPeers[p]
+	cg.RUnlock()
 	return !block
 }
 

go-libp2p/p2p/net/connmgr/connmgr.go

@@ -169,8 +169,6 @@ func (cm *BasicConnMgr) memoryEmergency() {
 	}
 
 	cm.trimMutex.Lock()
-	defer atomic.AddUint64(&cm.trimCount, 1)
-	defer cm.trimMutex.Unlock()
 
 	// Trim connections without paying attention to the silence period.
 	for _, c := range cm.getConnsToCloseEmergency(target) {
@@ -182,6 +180,8 @@ func (cm *BasicConnMgr) memoryEmergency() {
 	cm.lastTrimMu.Lock()
 	cm.lastTrim = cm.clock.Now()
 	cm.lastTrimMu.Unlock()
+	atomic.AddUint64(&cm.trimCount, 1)
+	cm.trimMutex.Unlock()
 }
 
 func (cm *BasicConnMgr) Close() error {
@@ -198,7 +198,6 @@ func (cm *BasicConnMgr) Close() error {
 
 func (cm *BasicConnMgr) Protect(id peer.ID, tag string) {
 	cm.plk.Lock()
-	defer cm.plk.Unlock()
 
 	tags, ok := cm.protected[id]
 	if !ok {
@@ -206,37 +205,42 @@ func (cm *BasicConnMgr) Protect(id peer.ID, tag string) {
 		cm.protected[id] = tags
 	}
 	tags[tag] = struct{}{}
+	cm.plk.Unlock()
 }
 
 func (cm *BasicConnMgr) Unprotect(id peer.ID, tag string) (protected bool) {
 	cm.plk.Lock()
-	defer cm.plk.Unlock()
 
 	tags, ok := cm.protected[id]
 	if !ok {
+		cm.plk.Unlock()
 		return false
 	}
 	if delete(tags, tag); len(tags) == 0 {
 		delete(cm.protected, id)
+		cm.plk.Unlock()
 		return false
 	}
+	cm.plk.Unlock()
 	return true
 }
 
 func (cm *BasicConnMgr) IsProtected(id peer.ID, tag string) (protected bool) {
 	cm.plk.Lock()
-	defer cm.plk.Unlock()
 
 	tags, ok := cm.protected[id]
 	if !ok {
+		cm.plk.Unlock()
 		return false
 	}
 
 	if tag == "" {
+		cm.plk.Unlock()
 		return true
 	}
 
 	_, protected = tags[tag]
+	cm.plk.Unlock()
 	return protected
 }
 
@@ -281,22 +285,30 @@ func (p peerInfos) SortByValueAndStreams(segments *segments, sortByMoreStreams b
 		// lock this to protect from concurrent modifications from connect/disconnect events
 		leftSegment := segments.get(left.id)
 		leftSegment.Lock()
-		defer leftSegment.Unlock()
 
 		rightSegment := segments.get(right.id)
+		rsLocked := false
 		if leftSegment != rightSegment {
 			// These two peers are not in the same segment, lets get the lock
 			rightSegment.Lock()
-			defer rightSegment.Unlock()
+			rsLocked = true
 		}
 		segments.bucketsMu.Unlock()
 
 		// temporary peers are preferred for pruning.
 		if left.temp != right.temp {
+			leftSegment.Unlock()
+			if rsLocked {
+				rightSegment.Unlock()
+			}
 			return left.temp
 		}
 		// otherwise, compare by value.
 		if left.value != right.value {
+			leftSegment.Unlock()
+			if rsLocked {
+				rightSegment.Unlock()
+			}
 			return left.value < right.value
 		}
 		incomingAndStreams := func(m map[network.Conn]time.Time) (incoming bool, numStreams int) {
@@ -313,13 +325,25 @@ func (p peerInfos) SortByValueAndStreams(segments *segments, sortByMoreStreams b
 		rightIncoming, rightStreams := incomingAndStreams(right.conns)
 		// prefer closing inactive connections (no streams open)
 		if rightStreams != leftStreams && (leftStreams == 0 || rightStreams == 0) {
+			leftSegment.Unlock()
+			if rsLocked {
+				rightSegment.Unlock()
+			}
 			return leftStreams < rightStreams
 		}
 		// incoming connections are preferred for pruning
 		if leftIncoming != rightIncoming {
+			leftSegment.Unlock()
+			if rsLocked {
+				rightSegment.Unlock()
+			}
 			return leftIncoming
 		}
 
+		leftSegment.Unlock()
+		if rsLocked {
+			rightSegment.Unlock()
+		}
 		if sortByMoreStreams {
 			// prune connections with a higher number of streams first
 			return rightStreams < leftStreams
@@ -345,15 +369,12 @@ func (cm *BasicConnMgr) TrimOpenConns(_ context.Context) {
 }
 
 func (cm *BasicConnMgr) background() {
-	defer cm.refCount.Done()
-
 	interval := cm.cfg.gracePeriod / 2
 	if cm.cfg.silencePeriod != 0 {
 		interval = cm.cfg.silencePeriod
 	}
 
 	ticker := cm.clock.Ticker(interval)
-	defer ticker.Stop()
 
 	for {
 		select {
@@ -363,6 +384,8 @@ func (cm *BasicConnMgr) background() {
 				continue
 			}
 		case <-cm.ctx.Done():
+			cm.refCount.Done()
+			ticker.Stop()
 			return
 		}
 		cm.trim()
@@ -373,7 +396,6 @@ func (cm *BasicConnMgr) doTrim() {
 	// This logic is mimicking the implementation of sync.Once in the standard library.
 	count := atomic.LoadUint64(&cm.trimCount)
 	cm.trimMutex.Lock()
-	defer cm.trimMutex.Unlock()
 	if count == atomic.LoadUint64(&cm.trimCount) {
 		cm.trim()
 		cm.lastTrimMu.Lock()
@@ -381,6 +403,7 @@ func (cm *BasicConnMgr) doTrim() {
 		cm.lastTrimMu.Unlock()
 		atomic.AddUint64(&cm.trimCount, 1)
 	}
+	cm.trimMutex.Unlock()
 }
 
 // trim starts the trim, if the last trim happened before the configured silence period.
@@ -544,10 +567,10 @@ func (cm *BasicConnMgr) getConnsToClose() []network.Conn {
 func (cm *BasicConnMgr) GetTagInfo(p peer.ID) *connmgr.TagInfo {
 	s := cm.segments.get(p)
 	s.Lock()
-	defer s.Unlock()
 
 	pi, ok := s.peers[p]
 	if !ok {
+		s.Unlock()
 		return nil
 	}
 
@@ -567,7 +590,7 @@ func (cm *BasicConnMgr) GetTagInfo(p peer.ID) *connmgr.TagInfo {
 	for c, t := range pi.conns {
 		out.Conns[c.RemoteMultiaddr().String()] = t
 	}
-
+	s.Unlock()
 	return out
 }
 
@@ -575,37 +598,37 @@ func (cm *BasicConnMgr) GetTagInfo(p peer.ID) *connmgr.TagInfo {
 func (cm *BasicConnMgr) TagPeer(p peer.ID, tag string, val int) {
 	s := cm.segments.get(p)
 	s.Lock()
-	defer s.Unlock()
 
 	pi := s.tagInfoFor(p, cm.clock.Now())
 
 	// Update the total value of the peer.
 	pi.value += val - pi.tags[tag]
 	pi.tags[tag] = val
+	s.Unlock()
 }
 
 // UntagPeer is called to disassociate a string and integer from a given peer.
 func (cm *BasicConnMgr) UntagPeer(p peer.ID, tag string) {
 	s := cm.segments.get(p)
 	s.Lock()
-	defer s.Unlock()
 
 	pi, ok := s.peers[p]
 	if !ok {
 		log.Info("tried to remove tag from untracked peer: ", p)
+		s.Unlock()
 		return
 	}
 
 	// Update the total value of the peer.
 	pi.value -= pi.tags[tag]
 	delete(pi.tags, tag)
+	s.Unlock()
 }
 
 // UpsertTag is called to insert/update a peer tag
 func (cm *BasicConnMgr) UpsertTag(p peer.ID, tag string, upsert func(int) int) {
 	s := cm.segments.get(p)
 	s.Lock()
-	defer s.Unlock()
 
 	pi := s.tagInfoFor(p, cm.clock.Now())
 
@@ -613,6 +636,7 @@ func (cm *BasicConnMgr) UpsertTag(p peer.ID, tag string, upsert func(int) int) {
 	newval := upsert(oldval)
 	pi.value += newval - oldval
 	pi.tags[tag] = newval
+	s.Unlock()
 }
 
 // CMInfo holds the configuration for BasicConnMgr, as well as status data.
@@ -670,7 +694,6 @@ func (nn *cmNotifee) Connected(n network.Network, c network.Conn) {
 	p := c.RemotePeer()
 	s := cm.segments.get(p)
 	s.Lock()
-	defer s.Unlock()
 
 	id := c.RemotePeer()
 	pinfo, ok := s.peers[id]
@@ -694,11 +717,13 @@ func (nn *cmNotifee) Connected(n network.Network, c network.Conn) {
 	_, ok = pinfo.conns[c]
 	if ok {
 		log.Error("received connected notification for conn we are already tracking: ", p)
+		s.Unlock()
 		return
 	}
 
 	pinfo.conns[c] = cm.clock.Now()
 	cm.connCount.Add(1)
+	s.Unlock()
 }
 
 // Disconnected is called by notifiers to inform that an existing connection has been closed or terminated.
@@ -709,17 +734,18 @@ func (nn *cmNotifee) Disconnected(n network.Network, c network.Conn) {
 	p := c.RemotePeer()
 	s := cm.segments.get(p)
 	s.Lock()
-	defer s.Unlock()
 
 	cinf, ok := s.peers[p]
 	if !ok {
 		log.Error("received disconnected notification for peer we are not tracking: ", p)
+		s.Unlock()
 		return
 	}
 
 	_, ok = cinf.conns[c]
 	if !ok {
 		log.Error("received disconnected notification for conn we are not tracking: ", p)
+		s.Unlock()
 		return
 	}
 
@@ -728,6 +754,7 @@ func (nn *cmNotifee) Disconnected(n network.Network, c network.Conn) {
 		delete(s.peers, p)
 	}
 	cm.connCount.Add(-1)
+	s.Unlock()
 }
 
 // Listen is no-op in this implementation.

go-libp2p/p2p/net/connmgr/decay.go

@@ -100,9 +100,9 @@ func NewDecayer(cfg *DecayerCfg, mgr *BasicConnMgr) (*decayer, error) {
 
 func (d *decayer) RegisterDecayingTag(name string, interval time.Duration, decayFn connmgr.DecayFn, bumpFn connmgr.BumpFn) (connmgr.DecayingTag, error) {
 	d.tagsMu.Lock()
-	defer d.tagsMu.Unlock()
 
 	if _, ok := d.knownTags[name]; ok {
+		d.tagsMu.Unlock()
 		return nil, fmt.Errorf("decaying tag with name %s already exists", name)
 	}
 
@@ -128,6 +128,7 @@ func (d *decayer) RegisterDecayingTag(name string, interval time.Duration, decay
 	}
 
 	d.knownTags[name] = tag
+	d.tagsMu.Unlock()
 	return tag, nil
 }
 
@@ -150,10 +151,7 @@ func (d *decayer) Close() error {
 //  2. Applies score bumps.
 //  3. Yields when closed.
 func (d *decayer) process() {
-	defer close(d.doneCh)
-
 	ticker := d.clock.Ticker(d.cfg.Resolution)
-	defer ticker.Stop()
 
 	var (
 		bmp   bumpCmd
@@ -276,6 +274,8 @@ func (d *decayer) process() {
 			}
 
 		case <-d.closeCh:
+			ticker.Stop()
+			close(d.doneCh)
 			return
 		}
 	}

go-libp2p/p2p/net/nat/nat.go

@@ -63,8 +63,8 @@ func DiscoverNAT(ctx context.Context) (*NAT, error) {
 	}
 	nat.refCount.Add(1)
 	go func() {
-		defer nat.refCount.Done()
 		nat.background()
+		nat.refCount.Done()
 	}()
 	return nat, nil
 }
@@ -101,15 +101,17 @@ func (nat *NAT) Close() error {
 
 func (nat *NAT) GetMapping(protocol string, port int) (addr netip.AddrPort, found bool) {
 	nat.mappingmu.Lock()
-	defer nat.mappingmu.Unlock()
 
 	if !nat.extAddr.IsValid() {
+		nat.mappingmu.Unlock()
 		return netip.AddrPort{}, false
 	}
 	extPort, found := nat.mappings[entry{protocol: protocol, port: port}]
 	if !found {
+		nat.mappingmu.Unlock()
 		return netip.AddrPort{}, false
 	}
+	nat.mappingmu.Unlock()
 	return netip.AddrPortFrom(nat.extAddr, uint16(extPort)), true
 }
 
@@ -126,9 +128,9 @@ func (nat *NAT) AddMapping(ctx context.Context, protocol string, port int) error
 	}
 
 	nat.mappingmu.Lock()
-	defer nat.mappingmu.Unlock()
 
 	if nat.closed {
+		nat.mappingmu.Unlock()
 		return errors.New("closed")
 	}
 
@@ -136,6 +138,7 @@ func (nat *NAT) AddMapping(ctx context.Context, protocol string, port int) error
 	// allowing users -- in the optimistic case -- to use results right after.
 	extPort := nat.establishMapping(ctx, protocol, port)
 	nat.mappings[entry{protocol: protocol, port: port}] = extPort
+	nat.mappingmu.Unlock()
 	return nil
 }
 
@@ -143,17 +146,19 @@ func (nat *NAT) AddMapping(ctx context.Context, protocol string, port int) error
 // It blocks until the NAT has removed the mapping.
 func (nat *NAT) RemoveMapping(ctx context.Context, protocol string, port int) error {
 	nat.mappingmu.Lock()
-	defer nat.mappingmu.Unlock()
 
 	switch protocol {
 	case "tcp", "udp":
 		e := entry{protocol: protocol, port: port}
 		if _, ok := nat.mappings[e]; ok {
 			delete(nat.mappings, e)
+			nat.mappingmu.Unlock()
 			return nat.nat.DeletePortMapping(ctx, protocol, port)
 		}
+		nat.mappingmu.Unlock()
 		return errors.New("unknown mapping")
 	default:
+		nat.mappingmu.Unlock()
 		return fmt.Errorf("invalid protocol: %s", protocol)
 	}
 }
@@ -166,7 +171,6 @@ func (nat *NAT) background() {
 	nextAddrUpdate := now.Add(CacheTime)
 
 	t := time.NewTimer(minTime(nextMappingUpdate, nextAddrUpdate).Sub(now)) // don't use a ticker here. We don't know how long establishing the mappings takes.
-	defer t.Stop()
 
 	var in []entry
 	var out []int // port numbers
@@ -209,12 +213,13 @@ func (nat *NAT) background() {
 		case <-nat.ctx.Done():
 			nat.mappingmu.Lock()
 			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-			defer cancel()
 			for e := range nat.mappings {
 				delete(nat.mappings, e)
 				nat.nat.DeletePortMapping(ctx, e.protocol, e.port)
 			}
 			nat.mappingmu.Unlock()
+			t.Stop()
+			cancel()
 			return
 		}
 	}

go-libp2p/p2p/net/pnet/psk_conn.go

@@ -60,11 +60,12 @@ func (c *pskConn) Write(in []byte) (int, error) {
 		c.writeS20 = salsa20.New(c.psk, nonce)
 	}
 	out := pool.Get(len(in))
-	defer pool.Put(out)
 
 	c.writeS20.XORKeyStream(out, in) // encrypt
 
-	return c.Conn.Write(out) // send
+	n, err := c.Conn.Write(out)
+	pool.Put(out)
+	return n, err // send
 }
 
 var _ net.Conn = (*pskConn)(nil)

go-libp2p/p2p/net/pnet/psk_conn_test.go

@@ -25,7 +25,6 @@ func setupPSKConns(ctx context.Context, t *testing.T) (net.Conn, net.Conn) {
 
 func TestPSKSimpelMessges(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.TODO())
-	defer cancel()
 
 	psk1, psk2 := setupPSKConns(ctx, t)
 	msg1 := []byte("hello world")
@@ -53,11 +52,11 @@ func TestPSKSimpelMessges(t *testing.T) {
 	if !bytes.Equal(msg1, out1) {
 		t.Fatalf("input and output are not the same")
 	}
+	cancel()
 }
 
 func TestPSKFragmentation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.TODO())
-	defer cancel()
 
 	psk1, psk2 := setupPSKConns(ctx, t)
 
@@ -87,4 +86,5 @@ func TestPSKFragmentation(t *testing.T) {
 	if err := <-wch; err != nil {
 		t.Fatal(err)
 	}
+	cancel()
 }

go-libp2p/p2p/net/reuseport/dial.go

@@ -51,12 +51,12 @@ func (n *network) getDialer(network string) *dialer {
 	n.mu.RUnlock()
 	if d == nil {
 		n.mu.Lock()
-		defer n.mu.Unlock()
 
 		if n.dialer == nil {
 			n.dialer = newDialer(n.listeners)
 		}
 		d = n.dialer
+		n.mu.Unlock()
 	}
 	return d
 }

go-libp2p/p2p/net/reuseport/listen.go

@@ -68,7 +68,6 @@ func (t *Transport) Listen(laddr ma.Multiaddr) (manet.Listener, error) {
 	}
 
 	n.mu.Lock()
-	defer n.mu.Unlock()
 
 	if n.listeners == nil {
 		n.listeners = make(map[*listener]struct{})
@@ -76,5 +75,6 @@ func (t *Transport) Listen(laddr ma.Multiaddr) (manet.Listener, error) {
 	n.listeners[list] = struct{}{}
 	n.dialer = nil
 
+	n.mu.Unlock()
 	return list, nil
 }

go-libp2p/p2p/net/swarm/black_hole_detector.go

@@ -77,13 +77,13 @@ type blackHoleFilter struct {
 // fraction over the last n outcomes is less than the minSuccessFraction of the filter.
 func (b *blackHoleFilter) RecordResult(success bool) {
 	b.mu.Lock()
-	defer b.mu.Unlock()
 
 	if b.state == blackHoleStateBlocked && success {
 		// If the call succeeds in a blocked state we reset to allowed.
 		// This is better than slowly accumulating values till we cross the minSuccessFraction
 		// threshold since a blackhole is a binary property.
 		b.reset()
+		b.mu.Unlock()
 		return
 	}
 
@@ -101,22 +101,25 @@ func (b *blackHoleFilter) RecordResult(success bool) {
 
 	b.updateState()
 	b.trackMetrics()
+	b.mu.Unlock()
 }
 
 // HandleRequest returns the result of applying the black hole filter for the request.
 func (b *blackHoleFilter) HandleRequest() blackHoleResult {
 	b.mu.Lock()
-	defer b.mu.Unlock()
 
 	b.requests++
 
 	b.trackMetrics()
 
 	if b.state == blackHoleStateAllowed {
+		b.mu.Unlock()
 		return blackHoleResultAllowed
 	} else if b.state == blackHoleStateProbing || b.requests%b.n == 0 {
+		b.mu.Unlock()
 		return blackHoleResultProbing
 	} else {
+		b.mu.Unlock()
 		return blackHoleResultBlocked
 	}
 }

go-libp2p/p2p/net/swarm/connectedness_event_emitter.go

@@ -50,18 +50,19 @@ func newConnectednessEventEmitter(connectedness func(peer.ID) network.Connectedn
 
 func (c *connectednessEventEmitter) AddConn(p peer.ID) {
 	c.mx.RLock()
-	defer c.mx.RUnlock()
 	if c.ctx.Err() != nil {
+		c.mx.RUnlock()
 		return
 	}
 
 	c.newConns <- p
+	c.mx.RUnlock()
 }
 
 func (c *connectednessEventEmitter) RemoveConn(p peer.ID) {
 	c.mx.RLock()
-	defer c.mx.RUnlock()
 	if c.ctx.Err() != nil {
+		c.mx.RUnlock()
 		return
 	}
 
@@ -80,6 +81,7 @@ func (c *connectednessEventEmitter) RemoveConn(p peer.ID) {
 	case c.removeConnNotif <- struct{}{}:
 	default:
 	}
+	c.mx.RUnlock()
 }
 
 func (c *connectednessEventEmitter) Close() {
@@ -88,7 +90,6 @@ func (c *connectednessEventEmitter) Close() {
 }
 
 func (c *connectednessEventEmitter) runEmitter() {
-	defer c.wg.Done()
 	for {
 		select {
 		case p := <-c.newConns:
@@ -97,7 +98,6 @@ func (c *connectednessEventEmitter) runEmitter() {
 			c.sendConnRemovedNotifications()
 		case <-c.ctx.Done():
 			c.mx.Lock() // Wait for all pending AddConn & RemoveConn operations to complete
-			defer c.mx.Unlock()
 			for {
 				select {
 				case p := <-c.newConns:
@@ -105,6 +105,8 @@ func (c *connectednessEventEmitter) runEmitter() {
 				case <-c.removeConnNotif:
 					c.sendConnRemovedNotifications()
 				default:
+					c.mx.Unlock()
+					c.wg.Done()
 					return
 				}
 			}

go-libp2p/p2p/net/swarm/dial_sync.go

@@ -67,7 +67,6 @@ func (ad *activeDial) dial(ctx context.Context) (*Conn, error) {
 
 func (ds *dialSync) getActiveDial(p peer.ID) (*activeDial, error) {
 	ds.mutex.Lock()
-	defer ds.mutex.Unlock()
 
 	actd, ok := ds.dials[p]
 	if !ok {
@@ -84,6 +83,7 @@ func (ds *dialSync) getActiveDial(p peer.ID) (*activeDial, error) {
 	}
 	// increase ref count before dropping mutex
 	actd.refCnt++
+	ds.mutex.Unlock()
 	return actd, nil
 }
 
@@ -98,7 +98,6 @@ func (ds *dialSync) Dial(ctx context.Context, p peer.ID) (*Conn, error) {
 	conn, err := ad.dial(ctx)
 
 	ds.mutex.Lock()
-	defer ds.mutex.Unlock()
 
 	ad.refCnt--
 	if ad.refCnt == 0 {
@@ -111,5 +110,6 @@ func (ds *dialSync) Dial(ctx context.Context, p peer.ID) (*Conn, error) {
 		delete(ds.dials, p)
 	}
 
+	ds.mutex.Unlock()
 	return conn, err
 }

go-libp2p/p2p/net/swarm/dial_worker.go

@@ -109,8 +109,6 @@ func newDialWorker(s *Swarm, p peer.ID, reqch <-chan dialRequest, cl Clock) *dia
 // The loop exits when w.reqch is closed.
 func (w *dialWorker) loop() {
 	w.wg.Add(1)
-	defer w.wg.Done()
-	defer w.s.limiter.clearAllPeerDials(w.peer)
 
 	// dq is used to pace dials to different addresses of the peer
 	dq := newDialQueue()
@@ -120,7 +118,6 @@ func (w *dialWorker) loop() {
 	startTime := w.cl.Now()
 	// dialTimer is the dialTimer used to trigger dials
 	dialTimer := w.cl.InstantTimer(startTime.Add(math.MaxInt64))
-	defer dialTimer.Stop()
 
 	timerRunning := true
 	// scheduleNextDial updates timer for triggering the next dial
@@ -164,6 +161,9 @@ loop:
 				if w.s.metricsTracer != nil {
 					w.s.metricsTracer.DialCompleted(w.connected, totalDials)
 				}
+				w.wg.Done()
+				w.s.limiter.clearAllPeerDials(w.peer)
+				dialTimer.Stop()
 				return
 			}
 			// We have received a new request. If we do not have a suitable connection,

go-libp2p/p2p/net/swarm/limiter.go

@@ -124,12 +124,12 @@ func (dl *dialLimiter) freePeerToken(dj *dialJob) {
 
 func (dl *dialLimiter) finishedDial(dj *dialJob) {
 	dl.lk.Lock()
-	defer dl.lk.Unlock()
 	if dl.shouldConsumeFd(dj.addr) {
 		dl.freeFDToken()
 	}
 
 	dl.freePeerToken(dj)
+	dl.lk.Unlock()
 }
 
 func (dl *dialLimiter) shouldConsumeFd(addr ma.Multiaddr) bool {
@@ -182,33 +182,32 @@ func (dl *dialLimiter) addCheckPeerLimit(dj *dialJob) {
 // it will put it on the waitlist for the requested token.
 func (dl *dialLimiter) AddDialJob(dj *dialJob) {
 	dl.lk.Lock()
-	defer dl.lk.Unlock()
 
 	log.Debugf("[limiter] adding a dial job through limiter: %v", dj.addr)
 	dl.addCheckPeerLimit(dj)
+	dl.lk.Unlock()
 }
 
 func (dl *dialLimiter) clearAllPeerDials(p peer.ID) {
 	dl.lk.Lock()
-	defer dl.lk.Unlock()
 	delete(dl.waitingOnPeerLimit, p)
 	log.Debugf("[limiter] clearing all peer dials: %v", p)
 	// NB: the waitingOnFd list doesn't need to be cleaned out here, we will
 	// remove them as we encounter them because they are 'cancelled' at this
 	// point
+	dl.lk.Unlock()
 }
 
 // executeDial calls the dialFunc, and reports the result through the response
 // channel when finished. Once the response is sent it also releases all tokens
 // it held during the dial.
 func (dl *dialLimiter) executeDial(j *dialJob) {
-	defer dl.finishedDial(j)
 	if j.cancelled() {
+		dl.finishedDial(j)
 		return
 	}
 
 	dctx, cancel := context.WithTimeout(j.ctx, j.timeout)
-	defer cancel()
 
 	con, err := dl.dialFunc(dctx, j.peer, j.addr, j.resp)
 	kind := transport.UpdateKindDialSuccessful
@@ -222,4 +221,6 @@ func (dl *dialLimiter) executeDial(j *dialJob) {
 			con.Close()
 		}
 	}
+	dl.finishedDial(j)
+	cancel()
 }

go-libp2p/p2p/net/swarm/swarm.go

@@ -328,10 +328,10 @@ func (s *Swarm) close() {
 		if closer, ok := t.(io.Closer); ok {
 			wg.Add(1)
 			go func(c io.Closer) {
-				defer wg.Done()
 				if err := closer.Close(); err != nil {
 					log.Errorf("error when closing down transport %T: %s", c, err)
 				}
+				wg.Done()
 			}(closer)
 		}
 	}
@@ -526,14 +526,12 @@ func (s *Swarm) waitForDirectConn(ctx context.Context, p peer.ID) (*Conn, error)
 
 	// apply the DialPeer timeout
 	ctx, cancel := context.WithTimeout(ctx, network.GetDialPeerTimeout(ctx))
-	defer cancel()
 
 	// Wait for notification.
 	select {
 	case <-ctx.Done():
 		// Remove ourselves from the notification list
 		s.directConnNotifs.Lock()
-		defer s.directConnNotifs.Unlock()
 
 		s.directConnNotifs.m[p] = slices.DeleteFunc(
 			s.directConnNotifs.m[p],
@@ -542,17 +540,22 @@ func (s *Swarm) waitForDirectConn(ctx context.Context, p peer.ID) (*Conn, error)
 		if len(s.directConnNotifs.m[p]) == 0 {
 			delete(s.directConnNotifs.m, p)
 		}
+		s.directConnNotifs.Unlock()
+		cancel()
 		return nil, ctx.Err()
 	case <-ch:
 		// We do not need to remove ourselves from the list here as the notifier
 		// clears the map entry
 		c := s.bestConnToPeer(p)
 		if c == nil {
+			cancel()
 			return nil, network.ErrNoConn
 		}
 		if c.Stat().Limited {
+			cancel()
 			return nil, network.ErrLimitedConn
 		}
+		cancel()
 		return c, nil
 	}
 }
@@ -562,12 +565,12 @@ func (s *Swarm) ConnsToPeer(p peer.ID) []network.Conn {
 	// TODO: Consider sorting the connection list best to worst. Currently,
 	// it's sorted oldest to newest.
 	s.conns.RLock()
-	defer s.conns.RUnlock()
 	conns := s.conns.m[p]
 	output := make([]network.Conn, len(conns))
 	for i, c := range conns {
 		output[i] = c
 	}
+	s.conns.RUnlock()
 	return output
 }
 
@@ -610,7 +613,6 @@ func (s *Swarm) bestConnToPeer(p peer.ID) *Conn {
 	// For now, prefers direct connections over Relayed connections.
 	// For tie-breaking, select the newest non-closed connection with the most streams.
 	s.conns.RLock()
-	defer s.conns.RUnlock()
 
 	var best *Conn
 	for _, c := range s.conns.m[p] {
@@ -622,6 +624,7 @@ func (s *Swarm) bestConnToPeer(p peer.ID) *Conn {
 			best = c
 		}
 	}
+	s.conns.RUnlock()
 	return best
 }
 
@@ -648,9 +651,9 @@ func isDirectConn(c *Conn) bool {
 // network.Connected`.
 func (s *Swarm) Connectedness(p peer.ID) network.Connectedness {
 	s.conns.RLock()
-	defer s.conns.RUnlock()
+	connectedness := s.connectednessUnlocked(p)
-
+	s.conns.RUnlock()
-	return s.connectednessUnlocked(p)
+	return connectedness
 }
 
 // connectednessUnlocked returns the connectedness of a peer.
@@ -676,7 +679,6 @@ func (s *Swarm) connectednessUnlocked(p peer.ID) network.Connectedness {
 // Conns returns a slice of all connections.
 func (s *Swarm) Conns() []network.Conn {
 	s.conns.RLock()
-	defer s.conns.RUnlock()
 
 	conns := make([]network.Conn, 0, len(s.conns.m))
 	for _, cs := range s.conns.m {
@@ -684,6 +686,7 @@ func (s *Swarm) Conns() []network.Conn {
 			conns = append(conns, c)
 		}
 	}
+	s.conns.RUnlock()
 	return conns
 }
 
@@ -720,12 +723,13 @@ func (s *Swarm) ClosePeer(p peer.ID) error {
 // Peers returns a copy of the set of peers swarm is connected to.
 func (s *Swarm) Peers() []peer.ID {
 	s.conns.RLock()
-	defer s.conns.RUnlock()
+
 	peers := make([]peer.ID, 0, len(s.conns.m))
 	for p := range s.conns.m {
 		peers = append(peers, p)
 	}
 
+	s.conns.RUnlock()
 	return peers
 }
 

go-libp2p/p2p/net/swarm/swarm_addr.go

@@ -11,8 +11,9 @@ import (
 // ListenAddresses returns a list of addresses at which this swarm listens.
 func (s *Swarm) ListenAddresses() []ma.Multiaddr {
 	s.listeners.RLock()
-	defer s.listeners.RUnlock()
+	mas := s.listenAddressesNoLock()
-	return s.listenAddressesNoLock()
+	s.listeners.RUnlock()
+	return mas
 }
 
 func (s *Swarm) listenAddressesNoLock() []ma.Multiaddr {

go-libp2p/p2p/net/swarm/swarm_conn.go

@@ -88,13 +88,13 @@ func (c *Conn) doClose() {
 	go func() {
 		// prevents us from issuing close notifications before finishing the open notifications
 		c.notifyLk.Lock()
-		defer c.notifyLk.Unlock()
 
 		// Only notify for disconnection if we notified for connection
 		c.swarm.notifyAll(func(f network.Notifiee) {
 			f.Disconnected(c.swarm, c)
 		})
 		c.swarm.refs.Done()
+		c.notifyLk.Unlock()
 	}()
 }
 
@@ -112,11 +112,11 @@ func (c *Conn) removeStream(s *Stream) {
 // swarm ref count.
 func (c *Conn) start() {
 	go func() {
-		defer c.swarm.refs.Done()
-		defer c.Close()
 		for {
 			ts, err := c.conn.AcceptStream()
 			if err != nil {
+				c.swarm.refs.Done()
+				c.Close()
 				return
 			}
 			scope, err := c.swarm.ResourceManager().OpenStream(c.RemotePeer(), network.DirInbound)
@@ -192,8 +192,9 @@ func (c *Conn) ConnState() network.ConnectionState {
 // Stat returns metadata pertaining to this connection
 func (c *Conn) Stat() network.ConnStats {
 	c.streams.Lock()
-	defer c.streams.Unlock()
+	stats := c.stat
-	return c.stat
+	c.streams.Unlock()
+	return stats
 }
 
 // NewStream returns a new Stream from this connection
@@ -260,11 +261,11 @@ func (c *Conn) addStream(ts network.MuxedStream, dir network.Direction, scope ne
 // GetStreams returns the streams associated with this connection.
 func (c *Conn) GetStreams() []network.Stream {
 	c.streams.Lock()
-	defer c.streams.Unlock()
 	streams := make([]network.Stream, 0, len(c.streams.m))
 	for s := range c.streams.m {
 		streams = append(streams, s)
 	}
+	c.streams.Unlock()
 	return streams
 }
 

go-libp2p/p2p/net/swarm/swarm_dial.go

@@ -122,10 +122,10 @@ func (db *DialBackoff) init(ctx context.Context) {
 
 func (db *DialBackoff) background(ctx context.Context) {
 	ticker := time.NewTicker(BackoffMax)
-	defer ticker.Stop()
 	for {
 		select {
 		case <-ctx.Done():
+			ticker.Stop()
 			return
 		case <-ticker.C:
 			db.cleanup()
@@ -137,9 +137,9 @@ func (db *DialBackoff) background(ctx context.Context) {
 // peer p at address addr
 func (db *DialBackoff) Backoff(p peer.ID, addr ma.Multiaddr) (backoff bool) {
 	db.lock.RLock()
-	defer db.lock.RUnlock()
 
 	ap, found := db.entries[p][string(addr.Bytes())]
+	db.lock.RUnlock()
 	return found && time.Now().Before(ap.until)
 }
 
@@ -163,7 +163,6 @@ var BackoffMax = time.Minute * 5
 func (db *DialBackoff) AddBackoff(p peer.ID, addr ma.Multiaddr) {
 	saddr := string(addr.Bytes())
 	db.lock.Lock()
-	defer db.lock.Unlock()
 	bp, ok := db.entries[p]
 	if !ok {
 		bp = make(map[string]*backoffAddr, 1)
@@ -175,6 +174,7 @@ func (db *DialBackoff) AddBackoff(p peer.ID, addr ma.Multiaddr) {
 			tries: 1,
 			until: time.Now().Add(BackoffBase),
 		}
+		db.lock.Unlock()
 		return
 	}
 
@@ -184,19 +184,19 @@ func (db *DialBackoff) AddBackoff(p peer.ID, addr ma.Multiaddr) {
 	}
 	ba.until = time.Now().Add(backoffTime)
 	ba.tries++
+	db.lock.Unlock()
 }
 
 // Clear removes a backoff record. Clients should call this after a
 // successful Dial.
 func (db *DialBackoff) Clear(p peer.ID) {
 	db.lock.Lock()
-	defer db.lock.Unlock()
 	delete(db.entries, p)
+	db.lock.Unlock()
 }
 
 func (db *DialBackoff) cleanup() {
 	db.lock.Lock()
-	defer db.lock.Unlock()
 	now := time.Now()
 	for p, e := range db.entries {
 		good := false
@@ -214,6 +214,7 @@ func (db *DialBackoff) cleanup() {
 			delete(db.entries, p)
 		}
 	}
+	db.lock.Unlock()
 }
 
 // DialPeer connects to a peer. Use network.WithForceDirectDial to force a
@@ -260,7 +261,6 @@ func (s *Swarm) dialPeer(ctx context.Context, p peer.ID) (*Conn, error) {
 
 	// apply the DialPeer timeout
 	ctx, cancel := context.WithTimeout(ctx, network.GetDialPeerTimeout(ctx))
-	defer cancel()
 
 	conn, err = s.dsync.Dial(ctx, p)
 	if err == nil {
@@ -269,8 +269,10 @@ func (s *Swarm) dialPeer(ctx context.Context, p peer.ID) (*Conn, error) {
 		if conn.RemotePeer() != p {
 			conn.Close()
 			log.Errorw("Handshake failed to properly authenticate peer", "authenticated", conn.RemotePeer(), "expected", p)
+			cancel()
 			return nil, fmt.Errorf("unexpected peer")
 		}
+		cancel()
 		return conn, nil
 	}
 
@@ -278,14 +280,17 @@ func (s *Swarm) dialPeer(ctx context.Context, p peer.ID) (*Conn, error) {
 
 	if ctx.Err() != nil {
 		// Context error trumps any dial errors as it was likely the ultimate cause.
+		cancel()
 		return nil, ctx.Err()
 	}
 
 	if s.ctx.Err() != nil {
 		// Ok, so the swarm is shutting down.
+		cancel()
 		return nil, ErrSwarmClosed
 	}
 
+	cancel()
 	return nil, err
 }
 

go-libp2p/p2p/net/swarm/swarm_listen.go

@@ -105,7 +105,7 @@ func (s *Swarm) AddListenAddr(a ma.Multiaddr) error {
 	})
 
 	go func() {
-		defer func() {
+		cleanup := func() {
 			s.listeners.Lock()
 			_, ok := s.listeners.m[list]
 			if ok {
@@ -124,13 +124,14 @@ func (s *Swarm) AddListenAddr(a ma.Multiaddr) error {
 				n.ListenClose(s, maddr)
 			})
 			s.refs.Done()
-		}()
+		}
 		for {
 			c, err := list.Accept()
 			if err != nil {
 				if !errors.Is(err, transport.ErrListenerClosed) {
 					log.Errorf("swarm listener for %s accept error: %s", a, err)
 				}
+				cleanup()
 				return
 			}
 			canonicallog.LogPeerStatus(100, c.RemotePeer(), c.RemoteMultiaddr(), "connection_status", "established", "dir", "inbound")
@@ -141,17 +142,19 @@ func (s *Swarm) AddListenAddr(a ma.Multiaddr) error {
 			log.Debugf("swarm listener accepted connection: %s <-> %s", c.LocalMultiaddr(), c.RemoteMultiaddr())
 			s.refs.Add(1)
 			go func() {
-				defer s.refs.Done()
 				_, err := s.addConn(c, network.DirInbound)
 				switch err {
 				case nil:
 				case ErrSwarmClosed:
 					// ignore.
+					s.refs.Done()
 					return
 				default:
 					log.Warnw("adding connection failed", "to", a, "error", err)
+					s.refs.Done()
 					return
 				}
+				s.refs.Done()
 			}()
 		}
 	}()

go-libp2p/p2p/net/swarm/swarm_metrics.go

@@ -183,7 +183,6 @@ func appendConnectionState(tags []string, cs network.ConnectionState) []string {
 
 func (m *metricsTracer) OpenedConnection(dir network.Direction, p crypto.PubKey, cs network.ConnectionState, laddr ma.Multiaddr) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, metricshelper.GetDirection(dir))
 	*tags = appendConnectionState(*tags, cs)
@@ -195,11 +194,11 @@ func (m *metricsTracer) OpenedConnection(dir network.Direction, p crypto.PubKey,
 	*tags = append(*tags, metricshelper.GetDirection(dir))
 	*tags = append(*tags, p.Type().String())
 	keyTypes.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func (m *metricsTracer) ClosedConnection(dir network.Direction, duration time.Duration, cs network.ConnectionState, laddr ma.Multiaddr) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, metricshelper.GetDirection(dir))
 	*tags = appendConnectionState(*tags, cs)
@@ -207,16 +206,17 @@ func (m *metricsTracer) ClosedConnection(dir network.Direction, duration time.Du
 	*tags = append(*tags, ipv)
 	connsClosed.WithLabelValues(*tags...).Inc()
 	connDuration.WithLabelValues(*tags...).Observe(duration.Seconds())
+	metricshelper.PutStringSlice(tags)
 }
 
 func (m *metricsTracer) CompletedHandshake(t time.Duration, cs network.ConnectionState, laddr ma.Multiaddr) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = appendConnectionState(*tags, cs)
 	ipv, _ := metricshelper.GetIPVersion(laddr)
 	*tags = append(*tags, ipv)
 	connHandshakeLatency.WithLabelValues(*tags...).Observe(t.Seconds())
+	metricshelper.PutStringSlice(tags)
 }
 
 func (m *metricsTracer) FailedDialing(addr ma.Multiaddr, dialErr error, cause error) {
@@ -246,17 +246,16 @@ func (m *metricsTracer) FailedDialing(addr ma.Multiaddr, dialErr error, cause er
 	}
 
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, transport, e)
 	ipv, _ := metricshelper.GetIPVersion(addr)
 	*tags = append(*tags, ipv)
 	dialError.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func (m *metricsTracer) DialCompleted(success bool, totalDials int) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 	if success {
 		*tags = append(*tags, "success")
 	} else {
@@ -272,6 +271,7 @@ func (m *metricsTracer) DialCompleted(success bool, totalDials int) {
 	}
 	*tags = append(*tags, numDials)
 	dialsPerPeer.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func (m *metricsTracer) DialRankingDelay(d time.Duration) {
@@ -281,11 +281,11 @@ func (m *metricsTracer) DialRankingDelay(d time.Duration) {
 func (m *metricsTracer) UpdatedBlackHoleFilterState(name string, state blackHoleState,
 	nextProbeAfter int, successFraction float64) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, name)
 
 	blackHoleFilterState.WithLabelValues(*tags...).Set(float64(state))
 	blackHoleFilterSuccessFraction.WithLabelValues(*tags...).Set(successFraction)
 	blackHoleFilterNextRequestAllowedAfter.WithLabelValues(*tags...).Set(float64(nextProbeAfter))
+	metricshelper.PutStringSlice(tags)
 }

go-libp2p/p2p/net/swarm/swarm_stream.go

@@ -93,8 +93,8 @@ func (s *Stream) Reset() error {
 
 func (s *Stream) closeAndRemoveStream() {
 	s.closeMx.Lock()
-	defer s.closeMx.Unlock()
 	if s.isClosed {
+		s.closeMx.Unlock()
 		return
 	}
 	s.isClosed = true
@@ -104,6 +104,7 @@ func (s *Stream) closeAndRemoveStream() {
 	if s.acceptStreamGoroutineCompleted {
 		s.conn.removeStream(s)
 	}
+	s.closeMx.Unlock()
 }
 
 // CloseWrite closes the stream for writing, flushing all data and sending an EOF.
@@ -121,14 +122,15 @@ func (s *Stream) CloseRead() error {
 
 func (s *Stream) completeAcceptStreamGoroutine() {
 	s.closeMx.Lock()
-	defer s.closeMx.Unlock()
 	if s.acceptStreamGoroutineCompleted {
+		s.closeMx.Unlock()
 		return
 	}
 	s.acceptStreamGoroutineCompleted = true
 	if s.isClosed {
 		s.conn.removeStream(s)
 	}
+	s.closeMx.Unlock()
 }
 
 // Protocol returns the protocol negotiated on this stream (if set).

go-libp2p/p2p/net/upgrader/conn.go

@@ -51,8 +51,9 @@ func (t *transportConn) Scope() network.ConnScope {
 }
 
 func (t *transportConn) Close() error {
-	defer t.scope.Done()
+	err := t.MuxedConn.Close()
-	return t.MuxedConn.Close()
+	t.scope.Done()
+	return err
 }
 
 func (t *transportConn) ConnState() network.ConnectionState {

go-libp2p/p2p/net/upgrader/listener.go

@@ -59,7 +59,7 @@ func (l *listener) Close() error {
 //     mechanism while still allowing us to negotiate connections in parallel.
 func (l *listener) handleIncoming() {
 	var wg sync.WaitGroup
-	defer func() {
+	cleanup := func() {
 		// make sure we're closed
 		l.Listener.Close()
 		if l.err == nil {
@@ -68,7 +68,7 @@ func (l *listener) handleIncoming() {
 
 		wg.Wait()
 		close(l.incoming)
-	}()
+	}
 
 	var catcher tec.TempErrCatcher
 	for l.ctx.Err() == nil {
@@ -80,6 +80,7 @@ func (l *listener) handleIncoming() {
 				continue
 			}
 			l.err = err
+			cleanup()
 			return
 		}
 		catcher.Reset()
@@ -114,10 +115,7 @@ func (l *listener) handleIncoming() {
 
 		wg.Add(1)
 		go func() {
-			defer wg.Done()
-
 			ctx, cancel := context.WithTimeout(l.ctx, l.upgrader.acceptTimeout)
-			defer cancel()
 
 			conn, err := l.upgrader.Upgrade(ctx, l.transport, maconn, network.DirInbound, "", connScope)
 			if err != nil {
@@ -128,6 +126,8 @@ func (l *listener) handleIncoming() {
 					maconn.LocalMultiaddr(),
 					maconn.RemoteMultiaddr())
 				connScope.Done()
+				wg.Done()
+				cancel()
 				return
 			}
 
@@ -139,7 +139,6 @@ func (l *listener) handleIncoming() {
 			// simply ensures that calls to Wait block while we're
 			// over the threshold.
 			l.threshold.Acquire()
-			defer l.threshold.Release()
 
 			select {
 			case l.incoming <- conn:
@@ -154,8 +153,12 @@ func (l *listener) handleIncoming() {
 				// instead of hanging onto them.
 				conn.Close()
 			}
+			wg.Done()
+			cancel()
+			l.threshold.Release()
 		}()
 	}
+	cleanup()
 }
 
 // Accept accepts a connection.

go-libp2p/p2p/protocol/circuitv2/client/conn.go

@@ -122,20 +122,19 @@ func (c *Conn) Stat() network.ConnStats {
 // implicitly because the connection manager closed the underlying relay connection.
 func (c *Conn) tagHop() {
 	c.client.mx.Lock()
-	defer c.client.mx.Unlock()
 
 	p := c.stream.Conn().RemotePeer()
 	c.client.hopCount[p]++
 	if c.client.hopCount[p] == 1 {
 		c.client.host.ConnManager().TagPeer(p, "relay-hop-stream", HopTagWeight)
 	}
+	c.client.mx.Unlock()
 }
 
 // untagHop removes the relay-hop-stream tag if necessary; it is invoked when a relayed connection
 // is closed.
 func (c *Conn) untagHop() {
 	c.client.mx.Lock()
-	defer c.client.mx.Unlock()
 
 	p := c.stream.Conn().RemotePeer()
 	c.client.hopCount[p]--
@@ -143,6 +142,7 @@ func (c *Conn) untagHop() {
 		c.client.host.ConnManager().UntagPeer(p, "relay-hop-stream")
 		delete(c.client.hopCount, p)
 	}
+	c.client.mx.Unlock()
 }
 
 type capableConnWithStat interface {

go-libp2p/p2p/protocol/circuitv2/client/dial.go

@@ -130,12 +130,15 @@ func (c *Client) dialPeer(ctx context.Context, relay, dest peer.AddrInfo) (*Conn
 	}
 
 	dialCtx, cancel := context.WithTimeout(ctx, DialRelayTimeout)
-	defer cancel()
+
 	s, err := c.host.NewStream(dialCtx, relay.ID, proto.ProtoIDv2Hop)
 	if err != nil {
+		cancel()
 		return nil, fmt.Errorf("error opening hop stream to relay: %w", err)
 	}
-	return c.connect(s, dest)
+	conn, err := c.connect(s, dest)
+	cancel()
+	return conn, err
 }
 
 func (c *Client) connect(s network.Stream, dest peer.AddrInfo) (*Conn, error) {
@@ -143,11 +146,9 @@ func (c *Client) connect(s network.Stream, dest peer.AddrInfo) (*Conn, error) {
 		s.Reset()
 		return nil, err
 	}
-	defer s.Scope().ReleaseMemory(maxMessageSize)
 
 	rd := util.NewDelimitedReader(s, maxMessageSize)
 	wr := util.NewDelimitedWriter(s)
-	defer rd.Close()
 
 	var msg pbv2.HopMessage
 
@@ -159,6 +160,8 @@ func (c *Client) connect(s network.Stream, dest peer.AddrInfo) (*Conn, error) {
 	err := wr.WriteMsg(&msg)
 	if err != nil {
 		s.Reset()
+		s.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return nil, err
 	}
 
@@ -167,6 +170,8 @@ func (c *Client) connect(s network.Stream, dest peer.AddrInfo) (*Conn, error) {
 	err = rd.ReadMsg(&msg)
 	if err != nil {
 		s.Reset()
+		s.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return nil, err
 	}
 
@@ -174,12 +179,16 @@ func (c *Client) connect(s network.Stream, dest peer.AddrInfo) (*Conn, error) {
 
 	if msg.GetType() != pbv2.HopMessage_STATUS {
 		s.Reset()
+		s.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return nil, newRelayError("unexpected relay response; not a status message (%d)", msg.GetType())
 	}
 
 	status := msg.GetStatus()
 	if status != pbv2.Status_OK {
 		s.Reset()
+		s.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return nil, newRelayError("error opening relay circuit: %s (%d)", pbv2.Status_name[int32(status)], status)
 	}
 
@@ -193,5 +202,7 @@ func (c *Client) connect(s network.Stream, dest peer.AddrInfo) (*Conn, error) {
 		stat.Extra[StatLimitData] = limit.GetData()
 	}
 
+	s.Scope().ReleaseMemory(maxMessageSize)
+	rd.Close()
 	return &Conn{stream: s, remote: dest, stat: stat, client: c}, nil
 }

go-libp2p/p2p/protocol/circuitv2/client/handlers.go

@@ -19,18 +19,18 @@ func (c *Client) handleStreamV2(s network.Stream) {
 	s.SetReadDeadline(time.Now().Add(StreamTimeout))
 
 	rd := util.NewDelimitedReader(s, maxMessageSize)
-	defer rd.Close()
 
 	writeResponse := func(status pbv2.Status) error {
 		s.SetWriteDeadline(time.Now().Add(StreamTimeout))
-		defer s.SetWriteDeadline(time.Time{})
 		wr := util.NewDelimitedWriter(s)
 
 		var msg pbv2.StopMessage
 		msg.Type = pbv2.StopMessage_STATUS.Enum()
 		msg.Status = status.Enum()
 
-		return wr.WriteMsg(&msg)
+		err := wr.WriteMsg(&msg)
+		s.SetWriteDeadline(time.Time{})
+		return err
 	}
 
 	handleError := func(status pbv2.Status) {
@@ -49,6 +49,7 @@ func (c *Client) handleStreamV2(s network.Stream) {
 	err := rd.ReadMsg(&msg)
 	if err != nil {
 		handleError(pbv2.Status_MALFORMED_MESSAGE)
+		rd.Close()
 		return
 	}
 	// reset stream deadline as message has been read
@@ -56,12 +57,14 @@ func (c *Client) handleStreamV2(s network.Stream) {
 
 	if msg.GetType() != pbv2.StopMessage_CONNECT {
 		handleError(pbv2.Status_UNEXPECTED_MESSAGE)
+		rd.Close()
 		return
 	}
 
 	src, err := util.PeerToPeerInfoV2(msg.GetPeer())
 	if err != nil {
 		handleError(pbv2.Status_MALFORMED_MESSAGE)
+		rd.Close()
 		return
 	}
 
@@ -87,4 +90,5 @@ func (c *Client) handleStreamV2(s network.Stream) {
 	case <-time.After(AcceptTimeout):
 		handleError(pbv2.Status_CONNECTION_FAILED)
 	}
+	rd.Close()
 }

go-libp2p/p2p/protocol/circuitv2/client/reservation.go

@@ -69,11 +69,9 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 	if err != nil {
 		return nil, ReservationError{Status: pbv2.Status_CONNECTION_FAILED, Reason: "failed to open stream", err: err}
 	}
-	defer s.Close()
 
 	rd := util.NewDelimitedReader(s, maxMessageSize)
 	wr := util.NewDelimitedWriter(s)
-	defer rd.Close()
 
 	var msg pbv2.HopMessage
 	msg.Type = pbv2.HopMessage_RESERVE.Enum()
@@ -82,6 +80,8 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 
 	if err := wr.WriteMsg(&msg); err != nil {
 		s.Reset()
+		s.Close()
+		rd.Close()
 		return nil, ReservationError{Status: pbv2.Status_CONNECTION_FAILED, Reason: "error writing reservation message", err: err}
 	}
 
@@ -89,10 +89,14 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 
 	if err := rd.ReadMsg(&msg); err != nil {
 		s.Reset()
+		s.Close()
+		rd.Close()
 		return nil, ReservationError{Status: pbv2.Status_CONNECTION_FAILED, Reason: "error reading reservation response message: %w", err: err}
 	}
 
 	if msg.GetType() != pbv2.HopMessage_STATUS {
+		s.Close()
+		rd.Close()
 		return nil, ReservationError{
 			Status: pbv2.Status_MALFORMED_MESSAGE,
 			Reason: fmt.Sprintf("unexpected relay response: not a status message (%d)", msg.GetType()),
@@ -100,17 +104,23 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 	}
 
 	if status := msg.GetStatus(); status != pbv2.Status_OK {
+		s.Close()
+		rd.Close()
 		return nil, ReservationError{Status: msg.GetStatus(), Reason: "reservation failed"}
 	}
 
 	rsvp := msg.GetReservation()
 	if rsvp == nil {
+		s.Close()
+		rd.Close()
 		return nil, ReservationError{Status: pbv2.Status_MALFORMED_MESSAGE, Reason: "missing reservation info"}
 	}
 
 	result := &Reservation{}
 	result.Expiration = time.Unix(int64(rsvp.GetExpire()), 0)
 	if result.Expiration.Before(time.Now()) {
+		s.Close()
+		rd.Close()
 		return nil, ReservationError{
 			Status: pbv2.Status_MALFORMED_MESSAGE,
 			Reason: fmt.Sprintf("received reservation with expiration date in the past: %s", result.Expiration),
@@ -132,6 +142,8 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 	if voucherBytes != nil {
 		_, rec, err := record.ConsumeEnvelope(voucherBytes, proto.RecordDomain)
 		if err != nil {
+			s.Close()
+			rd.Close()
 			return nil, ReservationError{
 				Status: pbv2.Status_MALFORMED_MESSAGE,
 				Reason: fmt.Sprintf("error consuming voucher envelope: %s", err),
@@ -141,6 +153,8 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 
 		voucher, ok := rec.(*proto.ReservationVoucher)
 		if !ok {
+			s.Close()
+			rd.Close()
 			return nil, ReservationError{
 				Status: pbv2.Status_MALFORMED_MESSAGE,
 				Reason: fmt.Sprintf("unexpected voucher record type: %+T", rec),
@@ -155,5 +169,7 @@ func Reserve(ctx context.Context, h host.Host, ai peer.AddrInfo) (*Reservation,
 		result.LimitData = limit.GetData()
 	}
 
+	s.Close()
+	rd.Close()
 	return result, nil
 }

go-libp2p/p2p/protocol/circuitv2/relay/constraints.go

@@ -48,27 +48,30 @@ func newConstraints(rc *Resources) *constraints {
 // If adding this reservation violates IP constraints, an error is returned.
 func (c *constraints) AddReservation(p peer.ID, a ma.Multiaddr) error {
 	c.mutex.Lock()
-	defer c.mutex.Unlock()
 
 	now := time.Now()
 	c.cleanup(now)
 
 	if len(c.total) >= c.rc.MaxReservations {
+		c.mutex.Unlock()
 		return errTooManyReservations
 	}
 
 	ip, err := manet.ToIP(a)
 	if err != nil {
+		c.mutex.Unlock()
 		return errors.New("no IP address associated with peer")
 	}
 
 	peerReservations := c.peers[p]
 	if len(peerReservations) >= c.rc.MaxReservationsPerPeer {
+		c.mutex.Unlock()
 		return errTooManyReservationsForPeer
 	}
 
 	ipReservations := c.ips[ip.String()]
 	if len(ipReservations) >= c.rc.MaxReservationsPerIP {
+		c.mutex.Unlock()
 		return errTooManyReservationsForIP
 	}
 
@@ -79,6 +82,7 @@ func (c *constraints) AddReservation(p peer.ID, a ma.Multiaddr) error {
 		if asn != 0 {
 			asnReservations = c.asns[asn]
 			if len(asnReservations) >= c.rc.MaxReservationsPerASN {
+				c.mutex.Unlock()
 				return errTooManyReservationsForASN
 			}
 		}
@@ -97,6 +101,7 @@ func (c *constraints) AddReservation(p peer.ID, a ma.Multiaddr) error {
 		asnReservations = append(asnReservations, expiry)
 		c.asns[asn] = asnReservations
 	}
+	c.mutex.Unlock()
 	return nil
 }
 

go-libp2p/p2p/protocol/circuitv2/relay/metrics.go

@@ -163,24 +163,23 @@ func (mt *metricsTracer) RelayStatus(enabled bool) {
 
 func (mt *metricsTracer) ConnectionOpened() {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 	*tags = append(*tags, "opened")
 
 	connectionsTotal.WithLabelValues(*tags...).Add(1)
+	metricshelper.PutStringSlice(tags)
 }
 
 func (mt *metricsTracer) ConnectionClosed(d time.Duration) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 	*tags = append(*tags, "closed")
 
 	connectionsTotal.WithLabelValues(*tags...).Add(1)
 	connectionDurationSeconds.Observe(d.Seconds())
+	metricshelper.PutStringSlice(tags)
 }
 
 func (mt *metricsTracer) ConnectionRequestHandled(status pbv2.Status) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	respStatus := getResponseStatus(status)
 
@@ -191,11 +190,11 @@ func (mt *metricsTracer) ConnectionRequestHandled(status pbv2.Status) {
 		*tags = append(*tags, getRejectionReason(status))
 		connectionRejectionsTotal.WithLabelValues(*tags...).Add(1)
 	}
+	metricshelper.PutStringSlice(tags)
 }
 
 func (mt *metricsTracer) ReservationAllowed(isRenewal bool) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 	if isRenewal {
 		*tags = append(*tags, "renewed")
 	} else {
@@ -203,19 +202,19 @@ func (mt *metricsTracer) ReservationAllowed(isRenewal bool) {
 	}
 
 	reservationsTotal.WithLabelValues(*tags...).Add(1)
+	metricshelper.PutStringSlice(tags)
 }
 
 func (mt *metricsTracer) ReservationClosed(cnt int) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 	*tags = append(*tags, "closed")
 
 	reservationsTotal.WithLabelValues(*tags...).Add(float64(cnt))
+	metricshelper.PutStringSlice(tags)
 }
 
 func (mt *metricsTracer) ReservationRequestHandled(status pbv2.Status) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	respStatus := getResponseStatus(status)
 
@@ -226,6 +225,7 @@ func (mt *metricsTracer) ReservationRequestHandled(status pbv2.Status) {
 		*tags = append(*tags, getRejectionReason(status))
 		reservationRejectionsTotal.WithLabelValues(*tags...).Add(1)
 	}
+	metricshelper.PutStringSlice(tags)
 }
 
 func (mt *metricsTracer) BytesTransferred(cnt int) {

go-libp2p/p2p/protocol/circuitv2/relay/relay.go

@@ -146,10 +146,8 @@ func (r *Relay) handleStream(s network.Stream) {
 		s.Reset()
 		return
 	}
-	defer s.Scope().ReleaseMemory(maxMessageSize)
 
 	rd := util.NewDelimitedReader(s, maxMessageSize)
-	defer rd.Close()
 
 	s.SetReadDeadline(time.Now().Add(StreamTimeout))
 
@@ -158,6 +156,8 @@ func (r *Relay) handleStream(s network.Stream) {
 	err := rd.ReadMsg(&msg)
 	if err != nil {
 		r.handleError(s, pbv2.Status_MALFORMED_MESSAGE)
+		s.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return
 	}
 	// reset stream deadline as message has been read
@@ -176,22 +176,25 @@ func (r *Relay) handleStream(s network.Stream) {
 	default:
 		r.handleError(s, pbv2.Status_MALFORMED_MESSAGE)
 	}
+	s.Scope().ReleaseMemory(maxMessageSize)
+	rd.Close()
 }
 
 func (r *Relay) handleReserve(s network.Stream) pbv2.Status {
-	defer s.Close()
 	p := s.Conn().RemotePeer()
 	a := s.Conn().RemoteMultiaddr()
 
 	if isRelayAddr(a) {
 		log.Debugf("refusing relay reservation for %s; reservation attempt over relay connection")
 		r.handleError(s, pbv2.Status_PERMISSION_DENIED)
+		s.Close()
 		return pbv2.Status_PERMISSION_DENIED
 	}
 
 	if r.acl != nil && !r.acl.AllowReserve(p, a) {
 		log.Debugf("refusing relay reservation for %s; permission denied", p)
 		r.handleError(s, pbv2.Status_PERMISSION_DENIED)
+		s.Close()
 		return pbv2.Status_PERMISSION_DENIED
 	}
 
@@ -202,6 +205,7 @@ func (r *Relay) handleReserve(s network.Stream) pbv2.Status {
 		r.mx.Unlock()
 		log.Debugf("refusing relay reservation for %s; relay closed", p)
 		r.handleError(s, pbv2.Status_PERMISSION_DENIED)
+		s.Close()
 		return pbv2.Status_PERMISSION_DENIED
 	}
 	now := time.Now()
@@ -212,6 +216,7 @@ func (r *Relay) handleReserve(s network.Stream) pbv2.Status {
 			r.mx.Unlock()
 			log.Debugf("refusing relay reservation for %s; IP constraint violation: %s", p, err)
 			r.handleError(s, pbv2.Status_RESERVATION_REFUSED)
+			s.Close()
 			return pbv2.Status_RESERVATION_REFUSED
 		}
 	}
@@ -232,8 +237,10 @@ func (r *Relay) handleReserve(s network.Stream) pbv2.Status {
 	if err := r.writeResponse(s, pbv2.Status_OK, r.makeReservationMsg(p, expire), r.makeLimitMsg(p)); err != nil {
 		log.Debugf("error writing reservation response; retracting reservation for %s", p)
 		s.Reset()
+		s.Close()
 		return pbv2.Status_CONNECTION_FAILED
 	}
+	s.Close()
 	return pbv2.Status_OK
 }
 
@@ -324,7 +331,6 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 	}
 
 	ctx, cancel := context.WithTimeout(r.ctx, ConnectTimeout)
-	defer cancel()
 
 	ctx = network.WithNoDial(ctx, "relay connect")
 
@@ -333,6 +339,7 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 		log.Debugf("error opening relay stream to %s: %s", dest.ID, err)
 		cleanup()
 		r.handleError(s, pbv2.Status_CONNECTION_FAILED)
+		cancel()
 		return pbv2.Status_CONNECTION_FAILED
 	}
 
@@ -345,6 +352,7 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 	if err := bs.Scope().SetService(ServiceName); err != nil {
 		log.Debugf("error attaching stream to relay service: %s", err)
 		fail(pbv2.Status_RESOURCE_LIMIT_EXCEEDED)
+		cancel()
 		return pbv2.Status_RESOURCE_LIMIT_EXCEEDED
 	}
 
@@ -352,13 +360,12 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 	if err := bs.Scope().ReserveMemory(maxMessageSize, network.ReservationPriorityAlways); err != nil {
 		log.Debugf("error reserving memory for stream: %s", err)
 		fail(pbv2.Status_RESOURCE_LIMIT_EXCEEDED)
+		cancel()
 		return pbv2.Status_RESOURCE_LIMIT_EXCEEDED
 	}
-	defer bs.Scope().ReleaseMemory(maxMessageSize)
 
 	rd := util.NewDelimitedReader(bs, maxMessageSize)
 	wr := util.NewDelimitedWriter(bs)
-	defer rd.Close()
 
 	var stopmsg pbv2.StopMessage
 	stopmsg.Type = pbv2.StopMessage_CONNECT.Enum()
@@ -371,6 +378,10 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 	if err != nil {
 		log.Debugf("error writing stop handshake")
 		fail(pbv2.Status_CONNECTION_FAILED)
+
+		cancel()
+		bs.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return pbv2.Status_CONNECTION_FAILED
 	}
 
@@ -380,18 +391,30 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 	if err != nil {
 		log.Debugf("error reading stop response: %s", err.Error())
 		fail(pbv2.Status_CONNECTION_FAILED)
+
+		cancel()
+		bs.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return pbv2.Status_CONNECTION_FAILED
 	}
 
 	if t := stopmsg.GetType(); t != pbv2.StopMessage_STATUS {
 		log.Debugf("unexpected stop response; not a status message (%d)", t)
 		fail(pbv2.Status_CONNECTION_FAILED)
+
+		cancel()
+		bs.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return pbv2.Status_CONNECTION_FAILED
 	}
 
 	if status := stopmsg.GetStatus(); status != pbv2.Status_OK {
 		log.Debugf("relay stop failure: %d", status)
 		fail(pbv2.Status_CONNECTION_FAILED)
+
+		cancel()
+		bs.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return pbv2.Status_CONNECTION_FAILED
 	}
 
@@ -407,6 +430,10 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 		bs.Reset()
 		s.Reset()
 		cleanup()
+
+		cancel()
+		bs.Scope().ReleaseMemory(maxMessageSize)
+		rd.Close()
 		return pbv2.Status_CONNECTION_FAILED
 	}
 
@@ -437,6 +464,9 @@ func (r *Relay) handleConnect(s network.Stream, msg *pbv2.HopMessage) pbv2.Statu
 		go r.relayUnlimited(bs, s, dest.ID, src, done)
 	}
 
+	cancel()
+	bs.Scope().ReleaseMemory(maxMessageSize)
+	rd.Close()
 	return pbv2.Status_OK
 }
 
@@ -461,10 +491,7 @@ func (r *Relay) rmConn(p peer.ID) {
 }
 
 func (r *Relay) relayLimited(src, dest network.Stream, srcID, destID peer.ID, limit int64, done func()) {
-	defer done()
-
 	buf := pool.Get(r.rc.BufferSize)
-	defer pool.Put(buf)
 
 	limitedSrc := io.LimitReader(src, limit)
 
@@ -484,13 +511,13 @@ func (r *Relay) relayLimited(src, dest network.Stream, srcID, destID peer.ID, li
 	}
 
 	log.Debugf("relayed %d bytes from %s to %s", count, srcID, destID)
+
+	done()
+	pool.Put(buf)
 }
 
 func (r *Relay) relayUnlimited(src, dest network.Stream, srcID, destID peer.ID, done func()) {
-	defer done()
-
 	buf := pool.Get(r.rc.BufferSize)
-	defer pool.Put(buf)
 
 	count, err := r.copyWithBuffer(dest, src, buf)
 	if err != nil {
@@ -504,6 +531,9 @@ func (r *Relay) relayUnlimited(src, dest network.Stream, srcID, destID peer.ID,
 	}
 
 	log.Debugf("relayed %d bytes from %s to %s", count, srcID, destID)
+
+	done()
+	pool.Put(buf)
 }
 
 // errInvalidWrite means that a write returned an impossible count.
@@ -560,7 +590,6 @@ func (r *Relay) handleError(s network.Stream, status pbv2.Status) {
 
 func (r *Relay) writeResponse(s network.Stream, status pbv2.Status, rsvp *pbv2.Reservation, limit *pbv2.Limit) error {
 	s.SetWriteDeadline(time.Now().Add(StreamTimeout))
-	defer s.SetWriteDeadline(time.Time{})
 	wr := util.NewDelimitedWriter(s)
 
 	var msg pbv2.HopMessage
@@ -569,7 +598,9 @@ func (r *Relay) writeResponse(s network.Stream, status pbv2.Status, rsvp *pbv2.R
 	msg.Reservation = rsvp
 	msg.Limit = limit
 
-	return wr.WriteMsg(&msg)
+	err := wr.WriteMsg(&msg)
+	s.SetWriteDeadline(time.Time{})
+	return err
 }
 
 func (r *Relay) makeReservationMsg(p peer.ID, expire time.Time) *pbv2.Reservation {
@@ -629,13 +660,13 @@ func (r *Relay) makeLimitMsg(p peer.ID) *pbv2.Limit {
 
 func (r *Relay) background() {
 	ticker := time.NewTicker(time.Minute)
-	defer ticker.Stop()
 
 	for {
 		select {
 		case <-ticker.C:
 			r.gc()
 		case <-r.ctx.Done():
+			ticker.Stop()
 			return
 		}
 	}
@@ -643,7 +674,6 @@ func (r *Relay) background() {
 
 func (r *Relay) gc() {
 	r.mx.Lock()
-	defer r.mx.Unlock()
 
 	now := time.Now()
 	cnt := 0
@@ -663,6 +693,7 @@ func (r *Relay) gc() {
 			delete(r.conns, p)
 		}
 	}
+	r.mx.Unlock()
 }
 
 func (r *Relay) disconnected(n network.Network, c network.Conn) {

go-libp2p/p2p/protocol/holepunch/holepuncher.go

@@ -67,18 +67,21 @@ func newHolePuncher(h host.Host, ids identify.IDService, tracer *tracer, filter
 
 func (hp *holePuncher) beginDirectConnect(p peer.ID) error {
 	hp.closeMx.RLock()
-	defer hp.closeMx.RUnlock()
 	if hp.closed {
+		hp.closeMx.RUnlock()
 		return ErrClosed
 	}
 
 	hp.activeMx.Lock()
-	defer hp.activeMx.Unlock()
 	if _, ok := hp.active[p]; ok {
+		hp.activeMx.Unlock()
+		hp.closeMx.RUnlock()
 		return ErrHolePunchActive
 	}
 
 	hp.active[p] = struct{}{}
+	hp.activeMx.Unlock()
+	hp.closeMx.RUnlock()
 	return nil
 }
 
@@ -90,13 +93,11 @@ func (hp *holePuncher) DirectConnect(p peer.ID) error {
 		return err
 	}
 
-	defer func() {
+	err := hp.directConnect(p)
-		hp.activeMx.Lock()
+	hp.activeMx.Lock()
-		delete(hp.active, p)
+	delete(hp.active, p)
-		hp.activeMx.Unlock()
+	hp.activeMx.Unlock()
-	}()
+	return err
-
-	return hp.directConnect(p)
 }
 
 func (hp *holePuncher) directConnect(rp peer.ID) error {
@@ -181,14 +182,15 @@ func (hp *holePuncher) initiateHolePunch(rp peer.ID) ([]ma.Multiaddr, []ma.Multi
 	if err != nil {
 		return nil, nil, 0, fmt.Errorf("failed to open hole-punching stream: %w", err)
 	}
-	defer str.Close()
 
 	addr, obsAddr, rtt, err := hp.initiateHolePunchImpl(str)
 	if err != nil {
 		log.Debugf("%s", err)
 		str.Reset()
+		str.Close()
 		return addr, obsAddr, rtt, err
 	}
+	str.Close()
 	return addr, obsAddr, rtt, err
 }
 
@@ -200,7 +202,6 @@ func (hp *holePuncher) initiateHolePunchImpl(str network.Stream) ([]ma.Multiaddr
 	if err := str.Scope().ReserveMemory(maxMsgSize, network.ReservationPriorityAlways); err != nil {
 		return nil, nil, 0, fmt.Errorf("error reserving memory for stream: %s", err)
 	}
-	defer str.Scope().ReleaseMemory(maxMsgSize)
 
 	w := pbio.NewDelimitedWriter(str)
 	rd := pbio.NewDelimitedReader(str, maxMsgSize)
@@ -213,6 +214,7 @@ func (hp *holePuncher) initiateHolePunchImpl(str network.Stream) ([]ma.Multiaddr
 		obsAddrs = hp.filter.FilterLocal(str.Conn().RemotePeer(), obsAddrs)
 	}
 	if len(obsAddrs) == 0 {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return nil, nil, 0, errors.New("aborting hole punch initiation as we have no public address")
 	}
 
@@ -222,16 +224,19 @@ func (hp *holePuncher) initiateHolePunchImpl(str network.Stream) ([]ma.Multiaddr
 		ObsAddrs: addrsToBytes(obsAddrs),
 	}); err != nil {
 		str.Reset()
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return nil, nil, 0, err
 	}
 
 	// wait for a CONNECT message from the remote peer
 	var msg pb.HolePunch
 	if err := rd.ReadMsg(&msg); err != nil {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return nil, nil, 0, fmt.Errorf("failed to read CONNECT message from remote peer: %w", err)
 	}
 	rtt := time.Since(start)
 	if t := msg.GetType(); t != pb.HolePunch_CONNECT {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return nil, nil, 0, fmt.Errorf("expect CONNECT message, got %s", t)
 	}
 
@@ -241,12 +246,15 @@ func (hp *holePuncher) initiateHolePunchImpl(str network.Stream) ([]ma.Multiaddr
 	}
 
 	if len(addrs) == 0 {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return nil, nil, 0, errors.New("didn't receive any public addresses in CONNECT")
 	}
 
 	if err := w.WriteMsg(&pb.HolePunch{Type: pb.HolePunch_SYNC.Enum()}); err != nil {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return nil, nil, 0, fmt.Errorf("failed to send SYNC message for hole punching: %w", err)
 	}
+	str.Scope().ReleaseMemory(maxMsgSize)
 	return addrs, obsAddrs, rtt, nil
 }
 
@@ -269,17 +277,17 @@ func (nn *netNotifiee) Connected(_ network.Network, conn network.Conn) {
 	if conn.Stat().Direction == network.DirInbound && isRelayAddress(conn.RemoteMultiaddr()) {
 		hs.refCount.Add(1)
 		go func() {
-			defer hs.refCount.Done()
-
 			select {
 			// waiting for Identify here will allow us to access the peer's public and observed addresses
 			// that we can dial to for a hole punch.
 			case <-hs.ids.IdentifyWait(conn):
 			case <-hs.ctx.Done():
+				hs.refCount.Done()
 				return
 			}
 
 			_ = hs.DirectConnect(conn.RemotePeer())
+			hs.refCount.Done()
 		}()
 	}
 }

go-libp2p/p2p/protocol/holepunch/metrics.go

@@ -108,7 +108,6 @@ func NewMetricsTracer(opts ...MetricsTracerOption) MetricsTracer {
 func (mt *metricsTracer) HolePunchFinished(side string, numAttempts int,
 	remoteAddrs []ma.Multiaddr, localAddrs []ma.Multiaddr, directConn network.ConnMultiaddrs) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, side, getNumAttemptString(numAttempts))
 	var dipv, dtransport string
@@ -165,6 +164,7 @@ func (mt *metricsTracer) HolePunchFinished(side string, numAttempts int,
 
 	*tags = append(*tags, outcome)
 	hpOutcomesTotal.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func getNumAttemptString(numAttempt int) string {
@@ -177,11 +177,11 @@ func getNumAttemptString(numAttempt int) string {
 
 func (mt *metricsTracer) DirectDialFinished(success bool) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 	if success {
 		*tags = append(*tags, "success")
 	} else {
 		*tags = append(*tags, "failed")
 	}
 	directDialsTotal.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }

go-libp2p/p2p/protocol/holepunch/svc.go

@@ -93,8 +93,6 @@ func NewService(h host.Host, ids identify.IDService, opts ...Option) (*Service,
 }
 
 func (s *Service) watchForPublicAddr() {
-	defer s.refCount.Done()
-
 	log.Debug("waiting until we have at least one public address", "peer", s.host.ID())
 
 	// TODO: We should have an event here that fires when identify discovers a new
@@ -104,7 +102,6 @@ func (s *Service) watchForPublicAddr() {
 	duration := 250 * time.Millisecond
 	const maxDuration = 5 * time.Second
 	t := time.NewTimer(duration)
-	defer t.Stop()
 	for {
 		if containsPublicAddr(s.ids.OwnObservedAddrs()) {
 			log.Debug("Host now has a public address. Starting holepunch protocol.")
@@ -114,6 +111,8 @@ func (s *Service) watchForPublicAddr() {
 
 		select {
 		case <-s.ctx.Done():
+			s.refCount.Done()
+			t.Stop()
 			return
 		case <-t.C:
 			duration *= 2
@@ -128,15 +127,22 @@ func (s *Service) watchForPublicAddr() {
 	sub, err := s.host.EventBus().Subscribe(&event.EvtLocalReachabilityChanged{}, eventbus.Name("holepunch"))
 	if err != nil {
 		log.Debugf("failed to subscripe to Reachability event: %s", err)
+		s.refCount.Done()
+		t.Stop()
 		return
 	}
-	defer sub.Close()
 	for {
 		select {
 		case <-s.ctx.Done():
+			s.refCount.Done()
+			t.Stop()
+			sub.Close()
 			return
 		case e, ok := <-sub.Out():
 			if !ok {
+				s.refCount.Done()
+				t.Stop()
+				sub.Close()
 				return
 			}
 			if e.(event.EvtLocalReachabilityChanged).Reachability != network.ReachabilityPrivate {
@@ -146,6 +152,10 @@ func (s *Service) watchForPublicAddr() {
 			s.holePuncher = newHolePuncher(s.host, s.ids, s.tracer, s.filter)
 			s.holePuncherMx.Unlock()
 			close(s.hasPublicAddrsChan)
+
+			s.refCount.Done()
+			t.Stop()
+			sub.Close()
 			return
 		}
 	}
@@ -185,7 +195,6 @@ func (s *Service) incomingHolePunch(str network.Stream) (rtt time.Duration, remo
 		log.Debugf("error reserving memory for stream: %s", err)
 		return 0, nil, nil, err
 	}
-	defer str.Scope().ReleaseMemory(maxMsgSize)
 
 	wr := pbio.NewDelimitedWriter(str)
 	rd := pbio.NewDelimitedReader(str, maxMsgSize)
@@ -196,9 +205,11 @@ func (s *Service) incomingHolePunch(str network.Stream) (rtt time.Duration, remo
 	str.SetDeadline(time.Now().Add(StreamTimeout))
 
 	if err := rd.ReadMsg(msg); err != nil {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return 0, nil, nil, fmt.Errorf("failed to read message from initiator: %w", err)
 	}
 	if t := msg.GetType(); t != pb.HolePunch_CONNECT {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return 0, nil, nil, fmt.Errorf("expected CONNECT message from initiator but got %d", t)
 	}
 
@@ -209,6 +220,7 @@ func (s *Service) incomingHolePunch(str network.Stream) (rtt time.Duration, remo
 
 	log.Debugw("received hole punch request", "peer", str.Conn().RemotePeer(), "addrs", obsDial)
 	if len(obsDial) == 0 {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return 0, nil, nil, errors.New("expected CONNECT message to contain at least one address")
 	}
 
@@ -218,17 +230,21 @@ func (s *Service) incomingHolePunch(str network.Stream) (rtt time.Duration, remo
 	msg.ObsAddrs = addrsToBytes(ownAddrs)
 	tstart := time.Now()
 	if err := wr.WriteMsg(msg); err != nil {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return 0, nil, nil, fmt.Errorf("failed to write CONNECT message to initiator: %w", err)
 	}
 
 	// Read SYNC message
 	msg.Reset()
 	if err := rd.ReadMsg(msg); err != nil {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return 0, nil, nil, fmt.Errorf("failed to read message from initiator: %w", err)
 	}
 	if t := msg.GetType(); t != pb.HolePunch_SYNC {
+		str.Scope().ReleaseMemory(maxMsgSize)
 		return 0, nil, nil, fmt.Errorf("expected SYNC message from initiator but got %d", t)
 	}
+	str.Scope().ReleaseMemory(maxMsgSize)
 	return time.Since(tstart), obsDial, ownAddrs, nil
 }
 

go-libp2p/p2p/protocol/holepunch/tracer.go

@@ -259,9 +259,7 @@ func (t *tracer) HolePunchAttempt(p peer.ID) {
 // gc cleans up the peers map. This is only run when tracer is initialised with a non nil
 // EventTracer
 func (t *tracer) gc() {
-	defer t.refCount.Done()
 	timer := time.NewTicker(tracerGCInterval)
-	defer timer.Stop()
 
 	for {
 		select {
@@ -275,6 +273,8 @@ func (t *tracer) gc() {
 			}
 			t.mutex.Unlock()
 		case <-t.ctx.Done():
+			t.refCount.Done()
+			timer.Stop()
 			return
 		}
 	}

go-libp2p/p2p/protocol/holepunch/util.go

@@ -68,12 +68,13 @@ func holePunchConnect(ctx context.Context, host host.Host, pi peer.AddrInfo, isC
 	holePunchCtx := network.WithSimultaneousConnect(ctx, isClient, "hole-punching")
 	forceDirectConnCtx := network.WithForceDirectDial(holePunchCtx, "hole-punching")
 	dialCtx, cancel := context.WithTimeout(forceDirectConnCtx, dialTimeout)
-	defer cancel()
 
 	if err := host.Connect(dialCtx, pi); err != nil {
 		log.Debugw("hole punch attempt with peer failed", "peer ID", pi.ID, "error", err)
+		cancel()
 		return err
 	}
 	log.Debugw("hole punch successful", "peer", pi.ID)
+	cancel()
 	return nil
 }

go-libp2p/p2p/protocol/identify/id.go

@@ -258,8 +258,6 @@ func (ids *idService) Start() {
 }
 
 func (ids *idService) loop(ctx context.Context) {
-	defer ids.refCount.Done()
-
 	sub, err := ids.Host.EventBus().Subscribe(
 		[]any{&event.EvtLocalProtocolsUpdated{}, &event.EvtLocalAddressesUpdated{}},
 		eventbus.BufSize(256),
@@ -267,9 +265,9 @@ func (ids *idService) loop(ctx context.Context) {
 	)
 	if err != nil {
 		log.Errorf("failed to subscribe to events on the bus, err=%s", err)
+		ids.refCount.Done()
 		return
 	}
-	defer sub.Close()
 
 	// Send pushes from a separate Go routine.
 	// That way, we can end up with
@@ -278,11 +276,10 @@ func (ids *idService) loop(ctx context.Context) {
 	triggerPush := make(chan struct{}, 1)
 	ids.refCount.Add(1)
 	go func() {
-		defer ids.refCount.Done()
-
 		for {
 			select {
 			case <-ctx.Done():
+				ids.refCount.Done()
 				return
 			case <-triggerPush:
 				ids.sendPushes(ctx)
@@ -294,6 +291,8 @@ func (ids *idService) loop(ctx context.Context) {
 		select {
 		case e, ok := <-sub.Out():
 			if !ok {
+				sub.Close()
+				ids.refCount.Done()
 				return
 			}
 			if updated := ids.updateSnapshot(); !updated {
@@ -307,6 +306,8 @@ func (ids *idService) loop(ctx context.Context) {
 			default: // we already have one more push queued, no need to queue another one
 			}
 		case <-ctx.Done():
+			sub.Close()
+			ids.refCount.Done()
 			return
 		}
 	}
@@ -346,19 +347,22 @@ func (ids *idService) sendPushes(ctx context.Context) {
 		sem <- struct{}{}
 		wg.Add(1)
 		go func(c network.Conn) {
-			defer wg.Done()
-			defer func() { <-sem }()
 			ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
-			defer cancel()
 			str, err := ids.Host.NewStream(ctx, c.RemotePeer(), IDPush)
 			if err != nil { // connection might have been closed recently
+				cancel()
+				func() { <-sem }()
+				wg.Done()
 				return
 			}
 			// TODO: find out if the peer supports push if we didn't have any information about push support
 			if err := ids.sendIdentifyResp(str, true); err != nil {
 				log.Debugw("failed to send identify push", "peer", c.RemotePeer(), "error", err)
-				return
 			}
+
+			cancel()
+			func() { <-sem }()
+			wg.Done()
 		}(c)
 	}
 	wg.Wait()
@@ -402,7 +406,6 @@ func (ids *idService) IdentifyConn(c network.Conn) {
 // If successful, the peer store will contain the peer's addresses and supported protocols.
 func (ids *idService) IdentifyWait(c network.Conn) <-chan struct{} {
 	ids.connsMu.Lock()
-	defer ids.connsMu.Unlock()
 
 	e, found := ids.conns[c]
 	if !found {
@@ -412,6 +415,7 @@ func (ids *idService) IdentifyWait(c network.Conn) <-chan struct{} {
 			log.Debugw("connection not found in identify service", "peer", c.RemotePeer())
 			ch := make(chan struct{})
 			close(ch)
+			ids.connsMu.Unlock()
 			return ch
 		} else {
 			ids.addConnWithLock(c)
@@ -419,6 +423,7 @@ func (ids *idService) IdentifyWait(c network.Conn) <-chan struct{} {
 	}
 
 	if e.IdentifyWaitChan != nil {
+		ids.connsMu.Unlock()
 		return e.IdentifyWaitChan
 	}
 	// First call to IdentifyWait for this connection. Create the channel.
@@ -429,23 +434,23 @@ func (ids *idService) IdentifyWait(c network.Conn) <-chan struct{} {
 	// already, but that doesn't really matter. We'll fail to open a
 	// stream then forget the connection.
 	go func() {
-		defer close(e.IdentifyWaitChan)
 		if err := ids.identifyConn(c); err != nil {
 			log.Warnf("failed to identify %s: %s", c.RemotePeer(), err)
 			ids.emitters.evtPeerIdentificationFailed.Emit(event.EvtPeerIdentificationFailed{Peer: c.RemotePeer(), Reason: err})
-			return
 		}
+		close(e.IdentifyWaitChan)
 	}()
 
+	ids.connsMu.Unlock()
 	return e.IdentifyWaitChan
 }
 
 func (ids *idService) identifyConn(c network.Conn) error {
 	ctx, cancel := context.WithTimeout(context.Background(), Timeout)
-	defer cancel()
 	s, err := c.NewStream(network.WithAllowLimitedConn(ctx, "identify"))
 	if err != nil {
 		log.Debugw("error opening identify stream", "peer", c.RemotePeer(), "error", err)
+		cancel()
 		return err
 	}
 	s.SetDeadline(time.Now().Add(Timeout))
@@ -459,10 +464,13 @@ func (ids *idService) identifyConn(c network.Conn) error {
 	if err := msmux.SelectProtoOrFail(ID, s); err != nil {
 		log.Infow("failed negotiate identify protocol with peer", "peer", c.RemotePeer(), "error", err)
 		s.Reset()
+		cancel()
 		return err
 	}
 
-	return ids.handleIdentifyResponse(s, false)
+	err = ids.handleIdentifyResponse(s, false)
+	cancel()
+	return err
 }
 
 // handlePush handles incoming identify push streams
@@ -480,7 +488,6 @@ func (ids *idService) sendIdentifyResp(s network.Stream, isPush bool) error {
 		s.Reset()
 		return fmt.Errorf("failed to attaching stream to identify service: %w", err)
 	}
-	defer s.Close()
 
 	ids.currentSnapshot.Lock()
 	snapshot := ids.currentSnapshot.snapshot
@@ -493,6 +500,7 @@ func (ids *idService) sendIdentifyResp(s network.Stream, isPush bool) error {
 
 	log.Debugf("%s sending message to %s %s", ID, s.Conn().RemotePeer(), s.Conn().RemoteMultiaddr())
 	if err := ids.writeChunkedIdentifyMsg(s, mes); err != nil {
+		s.Close()
 		return err
 	}
 
@@ -501,17 +509,21 @@ func (ids *idService) sendIdentifyResp(s network.Stream, isPush bool) error {
 	}
 
 	ids.connsMu.Lock()
-	defer ids.connsMu.Unlock()
 	e, ok := ids.conns[s.Conn()]
 	// The connection might already have been closed.
 	// We *should* receive the Connected notification from the swarm before we're able to accept the peer's
 	// Identify stream, but if that for some reason doesn't work, we also wouldn't have a map entry here.
 	// The only consequence would be that we send a spurious Push to that peer later.
 	if !ok {
+		ids.connsMu.Unlock()
+		s.Close()
 		return nil
 	}
 	e.Sequence = snapshot.seq
 	ids.conns[s.Conn()] = e
+
+	ids.connsMu.Unlock()
+	s.Close()
 	return nil
 }
 
@@ -527,7 +539,6 @@ func (ids *idService) handleIdentifyResponse(s network.Stream, isPush bool) erro
 		s.Reset()
 		return err
 	}
-	defer s.Scope().ReleaseMemory(signedIDSize)
 
 	c := s.Conn()
 
@@ -537,11 +548,10 @@ func (ids *idService) handleIdentifyResponse(s network.Stream, isPush bool) erro
 	if err := readAllIDMessages(r, mes); err != nil {
 		log.Warn("error reading identify message: ", err)
 		s.Reset()
+		s.Scope().ReleaseMemory(signedIDSize)
 		return err
 	}
 
-	defer s.Close()
-
 	log.Debugf("%s received message from %s %s", s.Protocol(), c.RemotePeer(), c.RemoteMultiaddr())
 
 	ids.consumeMessage(mes, c, isPush)
@@ -551,9 +561,12 @@ func (ids *idService) handleIdentifyResponse(s network.Stream, isPush bool) erro
 	}
 
 	ids.connsMu.Lock()
-	defer ids.connsMu.Unlock()
+
 	e, ok := ids.conns[c]
 	if !ok { // might already have disconnected
+		ids.connsMu.Unlock()
+		s.Close()
+		s.Scope().ReleaseMemory(signedIDSize)
 		return nil
 	}
 	sup, err := ids.Host.Peerstore().SupportsProtocols(c.RemotePeer(), IDPush)
@@ -568,6 +581,10 @@ func (ids *idService) handleIdentifyResponse(s network.Stream, isPush bool) erro
 	}
 
 	ids.conns[c] = e
+
+	ids.connsMu.Unlock()
+	s.Close()
+	s.Scope().ReleaseMemory(signedIDSize)
 	return nil
 }
 
@@ -612,9 +629,9 @@ func (ids *idService) updateSnapshot() (updated bool) {
 	}
 
 	ids.currentSnapshot.Lock()
-	defer ids.currentSnapshot.Unlock()
 
 	if ids.currentSnapshot.snapshot.Equal(&snapshot) {
+		ids.currentSnapshot.Unlock()
 		return false
 	}
 
@@ -622,6 +639,7 @@ func (ids *idService) updateSnapshot() (updated bool) {
 	ids.currentSnapshot.snapshot = snapshot
 
 	log.Debugw("updating snapshot", "seq", snapshot.seq, "addrs", snapshot.addrs)
+	ids.currentSnapshot.Unlock()
 	return true
 }
 
@@ -1036,12 +1054,12 @@ func (nn *netNotifiee) Disconnected(_ network.Network, c network.Conn) {
 	// Last disconnect.
 	// Undo the setting of addresses to peer.ConnectedAddrTTL we did
 	ids.addrMu.Lock()
-	defer ids.addrMu.Unlock()
 
 	// This check MUST happen after acquiring the Lock as identify on a different connection
 	// might be trying to add addresses.
 	switch ids.Host.Network().Connectedness(c.RemotePeer()) {
 	case network.Connected, network.Limited:
+		ids.addrMu.Unlock()
 		return
 	}
 	// peerstore returns the elements in a random order as it uses a map to store the addresses
@@ -1059,6 +1077,7 @@ func (nn *netNotifiee) Disconnected(_ network.Network, c network.Conn) {
 	ids.Host.Peerstore().UpdateAddrs(c.RemotePeer(), peerstore.ConnectedAddrTTL, peerstore.TempAddrTTL)
 	ids.Host.Peerstore().AddAddrs(c.RemotePeer(), addrs[:n], peerstore.RecentlyConnectedAddrTTL)
 	ids.Host.Peerstore().UpdateAddrs(c.RemotePeer(), peerstore.TempAddrTTL, 0)
+	ids.addrMu.Unlock()
 }
 
 func (nn *netNotifiee) Listen(n network.Network, a ma.Multiaddr)      {}

go-libp2p/p2p/protocol/identify/metrics.go

@@ -133,7 +133,6 @@ func NewMetricsTracer(opts ...MetricsTracerOption) MetricsTracer {
 
 func (t *metricsTracer) TriggeredPushes(ev any) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	typ := "unknown"
 	switch ev.(type) {
@@ -144,19 +143,19 @@ func (t *metricsTracer) TriggeredPushes(ev any) {
 	}
 	*tags = append(*tags, typ)
 	pushesTriggered.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func (t *metricsTracer) IncrementPushSupport(s identifyPushSupport) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, getPushSupport(s))
 	connPushSupportTotal.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func (t *metricsTracer) IdentifySent(isPush bool, numProtocols int, numAddrs int) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	if isPush {
 		*tags = append(*tags, metricshelper.GetDirection(network.DirOutbound))
@@ -168,11 +167,11 @@ func (t *metricsTracer) IdentifySent(isPush bool, numProtocols int, numAddrs int
 
 	protocolsCount.Set(float64(numProtocols))
 	addrsCount.Set(float64(numAddrs))
+	metricshelper.PutStringSlice(tags)
 }
 
 func (t *metricsTracer) IdentifyReceived(isPush bool, numProtocols int, numAddrs int) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	if isPush {
 		*tags = append(*tags, metricshelper.GetDirection(network.DirInbound))
@@ -184,14 +183,15 @@ func (t *metricsTracer) IdentifyReceived(isPush bool, numProtocols int, numAddrs
 
 	numProtocolsReceived.Observe(float64(numProtocols))
 	numAddrsReceived.Observe(float64(numAddrs))
+	metricshelper.PutStringSlice(tags)
 }
 
 func (t *metricsTracer) ConnPushSupport(support identifyPushSupport) {
 	tags := metricshelper.GetStringSlice()
-	defer metricshelper.PutStringSlice(tags)
 
 	*tags = append(*tags, getPushSupport(support))
 	connPushSupportTotal.WithLabelValues(*tags...).Inc()
+	metricshelper.PutStringSlice(tags)
 }
 
 func getPushSupport(s identifyPushSupport) string {

go-libp2p/p2p/protocol/identify/nat_emitter.go

@@ -53,7 +53,6 @@ func newNATEmitter(h host.Host, o *ObservedAddrManager, eventInterval time.Durat
 }
 
 func (n *natEmitter) worker() {
-	defer n.wg.Done()
 	subCh := n.reachabilitySub.Out()
 	ticker := time.NewTicker(n.eventInterval)
 	pendingUpdate := false
@@ -86,6 +85,7 @@ func (n *natEmitter) worker() {
 				enoughTimeSinceLastUpdate = false
 			}
 		case <-n.ctx.Done():
+			n.wg.Done()
 			return
 		}
 	}

go-libp2p/p2p/protocol/identify/obsaddr.go

@@ -116,10 +116,10 @@ func (s *observerSet) cacheMultiaddr(addr ma.Multiaddr) ma.Multiaddr {
 	}
 
 	s.mu.Lock()
-	defer s.mu.Unlock()
 	// Check if some other go routine added this while we were waiting
 	res, ok = s.cachedMultiaddrs[addrStr]
 	if ok {
+		s.mu.Unlock()
 		return res
 	}
 	if s.cachedMultiaddrs == nil {
@@ -133,7 +133,9 @@ func (s *observerSet) cacheMultiaddr(addr ma.Multiaddr) ma.Multiaddr {
 		}
 	}
 	s.cachedMultiaddrs[addrStr] = ma.Join(s.ObservedTWAddr, addr)
-	return s.cachedMultiaddrs[addrStr]
+	mas := s.cachedMultiaddrs[addrStr]
+	s.mu.Unlock()
+	return mas
 }
 
 type observation struct {
@@ -202,9 +204,9 @@ func (o *ObservedAddrManager) AddrsFor(addr ma.Multiaddr) (addrs []ma.Multiaddr)
 		return nil
 	}
 	o.mu.RLock()
-	defer o.mu.RUnlock()
 	tw, err := thinWaistForm(o.normalize(addr))
 	if err != nil {
+		o.mu.RUnlock()
 		return nil
 	}
 
@@ -213,13 +215,13 @@ func (o *ObservedAddrManager) AddrsFor(addr ma.Multiaddr) (addrs []ma.Multiaddr)
 	for _, s := range observerSets {
 		res = append(res, s.cacheMultiaddr(tw.Rest))
 	}
+	o.mu.RUnlock()
 	return res
 }
 
 // Addrs return all activated observed addresses
 func (o *ObservedAddrManager) Addrs() []ma.Multiaddr {
 	o.mu.RLock()
-	defer o.mu.RUnlock()
 
 	m := make(map[string][]*observerSet)
 	for localTWStr := range o.externalAddrs {
@@ -231,6 +233,7 @@ func (o *ObservedAddrManager) Addrs() []ma.Multiaddr {
 			addrs = append(addrs, s.cacheMultiaddr(t.Rest))
 		}
 	}
+	o.mu.RUnlock()
 	return addrs
 }
 
@@ -282,13 +285,12 @@ func (o *ObservedAddrManager) Record(conn connMultiaddrs, observed ma.Multiaddr)
 }
 
 func (o *ObservedAddrManager) worker() {
-	defer o.wg.Done()
-
 	for {
 		select {
 		case obs := <-o.wch:
 			o.maybeRecordObservation(obs.conn, obs.observed)
 		case <-o.ctx.Done():
+			o.wg.Done()
 			return
 		}
 	}
@@ -372,12 +374,12 @@ func (o *ObservedAddrManager) maybeRecordObservation(conn connMultiaddrs, observ
 	log.Debugw("added own observed listen addr", "observed", observed)
 
 	o.mu.Lock()
-	defer o.mu.Unlock()
 	o.recordObservationUnlocked(conn, localTW, observedTW)
 	select {
 	case o.addrRecordedNotif <- struct{}{}:
 	default:
 	}
+	o.mu.Unlock()
 }
 
 func (o *ObservedAddrManager) recordObservationUnlocked(conn connMultiaddrs, localTW, observedTW thinWaist) {
@@ -453,16 +455,17 @@ func (o *ObservedAddrManager) removeConn(conn connMultiaddrs) {
 		return
 	}
 	o.mu.Lock()
-	defer o.mu.Unlock()
 
 	// normalize before obtaining the thinWaist so that we are always dealing
 	// with the normalized form of the address
 	localTW, err := thinWaistForm(o.normalize(conn.LocalMultiaddr()))
 	if err != nil {
+		o.mu.Unlock()
 		return
 	}
 	t, ok := o.localAddrs[string(localTW.Addr.Bytes())]
 	if !ok {
+		o.mu.Unlock()
 		return
 	}
 	t.Count--
@@ -472,11 +475,13 @@ func (o *ObservedAddrManager) removeConn(conn connMultiaddrs) {
 
 	observedTWAddr, ok := o.connObservedTWAddrs[conn]
 	if !ok {
+		o.mu.Unlock()
 		return
 	}
 	delete(o.connObservedTWAddrs, conn)
 	observer, err := getObserver(conn.RemoteMultiaddr())
 	if err != nil {
+		o.mu.Unlock()
 		return
 	}
 
@@ -485,11 +490,11 @@ func (o *ObservedAddrManager) removeConn(conn connMultiaddrs) {
 	case o.addrRecordedNotif <- struct{}{}:
 	default:
 	}
+	o.mu.Unlock()
 }
 
 func (o *ObservedAddrManager) getNATType() (tcpNATType, udpNATType network.NATDeviceType) {
 	o.mu.RLock()
-	defer o.mu.RUnlock()
 
 	var tcpCounts, udpCounts []int
 	var tcpTotal, udpTotal int
@@ -539,6 +544,7 @@ func (o *ObservedAddrManager) getNATType() (tcpNATType, udpNATType network.NATDe
 			udpNATType = network.NATDeviceTypeSymmetric
 		}
 	}
+	o.mu.RUnlock()
 	return
 }
 

go-libp2p/p2p/protocol/ping/ping.go

@@ -50,15 +50,11 @@ func (p *PingService) PingHandler(s network.Stream) {
 		s.Reset()
 		return
 	}
-	defer s.Scope().ReleaseMemory(PingSize)
 
 	buf := pool.Get(PingSize)
-	defer pool.Put(buf)
 
 	errCh := make(chan error, 1)
-	defer close(errCh)
 	timer := time.NewTimer(pingTimeout)
-	defer timer.Stop()
 
 	go func() {
 		select {
@@ -78,12 +74,22 @@ func (p *PingService) PingHandler(s network.Stream) {
 		_, err := io.ReadFull(s, buf)
 		if err != nil {
 			errCh <- err
+
+			s.Scope().ReleaseMemory(PingSize)
+			pool.Put(buf)
+			close(errCh)
+			timer.Stop()
 			return
 		}
 
 		_, err = s.Write(buf)
 		if err != nil {
 			errCh <- err
+
+			s.Scope().ReleaseMemory(PingSize)
+			pool.Put(buf)
+			close(errCh)
+			timer.Stop()
 			return
 		}
 
@@ -134,15 +140,14 @@ func Ping(ctx context.Context, h host.Host, p peer.ID) <-chan Result {
 
 	out := make(chan Result)
 	go func() {
-		defer close(out)
-		defer cancel()
-
 		for ctx.Err() == nil {
 			var res Result
 			res.RTT, res.Error = ping(s, ra)
 
 			// canceled, ignore everything.
 			if ctx.Err() != nil {
+				close(out)
+				cancel()
 				return
 			}
 
@@ -154,9 +159,13 @@ func Ping(ctx context.Context, h host.Host, p peer.ID) <-chan Result {
 			select {
 			case out <- res:
 			case <-ctx.Done():
+				close(out)
+				cancel()
 				return
 			}
 		}
+		close(out)
+		cancel()
 	}()
 	context.AfterFunc(ctx, func() {
 		// forces the ping to abort.
@@ -172,30 +181,40 @@ func ping(s network.Stream, randReader io.Reader) (time.Duration, error) {
 		s.Reset()
 		return 0, err
 	}
-	defer s.Scope().ReleaseMemory(2 * PingSize)
 
 	buf := pool.Get(PingSize)
-	defer pool.Put(buf)
 
 	if _, err := io.ReadFull(randReader, buf); err != nil {
+		s.Scope().ReleaseMemory(2 * PingSize)
+		pool.Put(buf)
 		return 0, err
 	}
 
 	before := time.Now()
 	if _, err := s.Write(buf); err != nil {
+		s.Scope().ReleaseMemory(2 * PingSize)
+		pool.Put(buf)
 		return 0, err
 	}
 
 	rbuf := pool.Get(PingSize)
-	defer pool.Put(rbuf)
 
 	if _, err := io.ReadFull(s, rbuf); err != nil {
+		s.Scope().ReleaseMemory(2 * PingSize)
+		pool.Put(buf)
+		pool.Put(rbuf)
 		return 0, err
 	}
 
 	if !bytes.Equal(buf, rbuf) {
+		s.Scope().ReleaseMemory(2 * PingSize)
+		pool.Put(buf)
+		pool.Put(rbuf)
 		return 0, errors.New("ping packet was incorrect")
 	}
 
+	s.Scope().ReleaseMemory(2 * PingSize)
+	pool.Put(buf)
+	pool.Put(rbuf)
 	return time.Since(before), nil
 }

go-libp2p/p2p/transport/quic/transport.go

@@ -194,15 +194,15 @@ func (t *transport) holePunch(ctx context.Context, raddr ma.Multiaddr, p peer.ID
 	if err != nil {
 		return nil, err
 	}
-	defer tr.DecreaseCount()
 
 	ctx, cancel := context.WithTimeout(ctx, HolePunchTimeout)
-	defer cancel()
 
 	key := holePunchKey{addr: addr.String(), peer: p}
 	t.holePunchingMx.Lock()
 	if _, ok := t.holePunching[key]; ok {
 		t.holePunchingMx.Unlock()
+		tr.DecreaseCount()
+		cancel()
 		return nil, fmt.Errorf("already punching hole for %s", addr)
 	}
 	connCh := make(chan tpt.CapableConn, 1)
@@ -210,11 +210,6 @@ func (t *transport) holePunch(ctx context.Context, raddr ma.Multiaddr, p peer.ID
 	t.holePunchingMx.Unlock()
 
 	var timer *time.Timer
-	defer func() {
-		if timer != nil {
-			timer.Stop()
-		}
-	}()
 
 	payload := make([]byte, 64)
 	var punchErr error
@@ -247,6 +242,11 @@ loop:
 			t.holePunchingMx.Lock()
 			delete(t.holePunching, key)
 			t.holePunchingMx.Unlock()
+			tr.DecreaseCount()
+			cancel()
+			if timer != nil {
+				timer.Stop()
+			}
 			return c, nil
 		case <-timer.C:
 		case <-ctx.Done():
@@ -256,14 +256,24 @@ loop:
 	}
 	// we only arrive here if punchErr != nil
 	t.holePunchingMx.Lock()
-	defer func() {
-		delete(t.holePunching, key)
-		t.holePunchingMx.Unlock()
-	}()
 	select {
 	case c := <-t.holePunching[key].connCh:
+		tr.DecreaseCount()
+		cancel()
+		if timer != nil {
+			timer.Stop()
+		}
+		delete(t.holePunching, key)
+		t.holePunchingMx.Unlock()
 		return c, nil
 	default:
+		tr.DecreaseCount()
+		cancel()
+		if timer != nil {
+			timer.Stop()
+		}
+		delete(t.holePunching, key)
+		t.holePunchingMx.Unlock()
 		return nil, punchErr
 	}
 }
@@ -294,7 +304,6 @@ func (t *transport) Listen(addr ma.Multiaddr) (tpt.Listener, error) {
 	}
 
 	t.listenersMu.Lock()
-	defer t.listenersMu.Unlock()
 	listeners := t.listeners[udpAddr.String()]
 	var underlyingListener *listener
 	var acceptRunner *acceptLoopRunner
@@ -304,16 +313,19 @@ func (t *transport) Listen(addr ma.Multiaddr) (tpt.Listener, error) {
 		acceptRunner = listeners[0].acceptRunnner
 		// Make sure our underlying listener is listening on the specified QUIC version
 		if _, ok := underlyingListener.localMultiaddrs[version]; !ok {
+			t.listenersMu.Unlock()
 			return nil, fmt.Errorf("can't listen on quic version %v, underlying listener doesn't support it", version)
 		}
 	} else {
 		ln, err := t.connManager.ListenQUIC(addr, &tlsConf, t.allowWindowIncrease)
 		if err != nil {
+			t.listenersMu.Unlock()
 			return nil, err
 		}
 		l, err := newListener(ln, t, t.localPeer, t.privKey, t.rcmgr)
 		if err != nil {
 			_ = ln.Close()
+			t.listenersMu.Unlock()
 			return nil, err
 		}
 		underlyingListener = &l
@@ -335,7 +347,7 @@ func (t *transport) Listen(addr ma.Multiaddr) (tpt.Listener, error) {
 
 	listeners = append(listeners, l)
 	t.listeners[udpAddr.String()] = listeners
-
+	t.listenersMu.Unlock()
 	return l, nil
 }
 
@@ -373,7 +385,6 @@ func (t *transport) Close() error {
 
 func (t *transport) CloseVirtualListener(l *virtualListener) error {
 	t.listenersMu.Lock()
-	defer t.listenersMu.Unlock()
 
 	var err error
 	listeners := t.listeners[l.udpAddr]
@@ -381,6 +392,7 @@ func (t *transport) CloseVirtualListener(l *virtualListener) error {
 		// This is the last virtual listener here, so we can close the underlying listener
 		err = l.listener.Close()
 		delete(t.listeners, l.udpAddr)
+		t.listenersMu.Unlock()
 		return err
 	}
 
@@ -394,6 +406,6 @@ func (t *transport) CloseVirtualListener(l *virtualListener) error {
 		}
 	}
 
+	t.listenersMu.Unlock()
 	return nil
-
 }

go-libp2p/p2p/transport/quicreuse/connmgr.go

@@ -89,17 +89,18 @@ func (c *ConnManager) ListenQUIC(addr ma.Multiaddr, tlsConf *tls.Config, allowWi
 	}
 
 	c.quicListenersMu.Lock()
-	defer c.quicListenersMu.Unlock()
 
 	key := laddr.String()
 	entry, ok := c.quicListeners[key]
 	if !ok {
 		tr, err := c.transportForListen(netw, laddr)
 		if err != nil {
+			c.quicListenersMu.Unlock()
 			return nil, err
 		}
 		ln, err := newQuicListener(tr, c.serverConfig)
 		if err != nil {
+			c.quicListenersMu.Unlock()
 			return nil, err
 		}
 		key = tr.LocalAddr().String()
@@ -110,16 +111,17 @@ func (c *ConnManager) ListenQUIC(addr ma.Multiaddr, tlsConf *tls.Config, allowWi
 		if entry.refCount <= 0 {
 			entry.ln.Close()
 		}
+		c.quicListenersMu.Unlock()
 		return nil, err
 	}
 	entry.refCount++
 	c.quicListeners[key] = entry
+	c.quicListenersMu.Unlock()
 	return l, nil
 }
 
 func (c *ConnManager) onListenerClosed(key string) {
 	c.quicListenersMu.Lock()
-	defer c.quicListenersMu.Unlock()
 
 	entry := c.quicListeners[key]
 	entry.refCount = entry.refCount - 1
@@ -129,6 +131,7 @@ func (c *ConnManager) onListenerClosed(key string) {
 	} else {
 		c.quicListeners[key] = entry
 	}
+	c.quicListenersMu.Unlock()
 }
 
 func (c *ConnManager) transportForListen(network string, laddr *net.UDPAddr) (refCountedQuicTransport, error) {

go-libp2p/p2p/transport/quicreuse/listener.go

@@ -55,16 +55,18 @@ func newQuicListener(tr refCountedQuicTransport, quicConfig *quic.Config) (*quic
 		SessionTicketsDisabled: true, // This is set for the config for client, but we set it here as well: https://github.com/quic-go/quic-go/issues/4029
 		GetConfigForClient: func(info *tls.ClientHelloInfo) (*tls.Config, error) {
 			cl.protocolsMu.Lock()
-			defer cl.protocolsMu.Unlock()
 			for _, proto := range info.SupportedProtos {
 				if entry, ok := cl.protocols[proto]; ok {
 					conf := entry.tlsConf
 					if conf.GetConfigForClient != nil {
+						cl.protocolsMu.Unlock()
 						return conf.GetConfigForClient(info)
 					}
+					cl.protocolsMu.Unlock()
 					return conf, nil
 				}
 			}
+			cl.protocolsMu.Unlock()
 			return nil, fmt.Errorf("no supported protocol found. offered: %+v", info.SupportedProtos)
 		},
 	}
@@ -81,25 +83,27 @@ func newQuicListener(tr refCountedQuicTransport, quicConfig *quic.Config) (*quic
 
 func (l *quicListener) allowWindowIncrease(conn quic.Connection, delta uint64) bool {
 	l.protocolsMu.Lock()
-	defer l.protocolsMu.Unlock()
 
 	conf, ok := l.protocols[conn.ConnectionState().TLS.NegotiatedProtocol]
 	if !ok {
+		l.protocolsMu.Unlock()
 		return false
 	}
+	l.protocolsMu.Unlock()
 	return conf.allowWindowIncrease(conn, delta)
 }
 
 func (l *quicListener) Add(tlsConf *tls.Config, allowWindowIncrease func(conn quic.Connection, delta uint64) bool, onRemove func()) (Listener, error) {
 	l.protocolsMu.Lock()
-	defer l.protocolsMu.Unlock()
 
 	if len(tlsConf.NextProtos) == 0 {
+		l.protocolsMu.Unlock()
 		return nil, errors.New("no ALPN found in tls.Config")
 	}
 
 	for _, proto := range tlsConf.NextProtos {
 		if _, ok := l.protocols[proto]; ok {
+			l.protocolsMu.Unlock()
 			return nil, fmt.Errorf("already listening for protocol %s", proto)
 		}
 	}
@@ -119,18 +123,21 @@ func (l *quicListener) Add(tlsConf *tls.Config, allowWindowIncrease func(conn qu
 			allowWindowIncrease: allowWindowIncrease,
 		}
 	}
+	l.protocolsMu.Unlock()
 	return ln, nil
 }
 
 func (l *quicListener) Run() error {
-	defer close(l.running)
-	defer l.transport.DecreaseCount()
 	for {
 		conn, err := l.l.Accept(context.Background())
 		if err != nil {
 			if errors.Is(err, quic.ErrServerClosed) || strings.Contains(err.Error(), "use of closed network connection") {
+				close(l.running)
+				l.transport.DecreaseCount()
 				return transport.ErrListenerClosed
 			}
+			close(l.running)
+			l.transport.DecreaseCount()
 			return err
 		}
 		proto := conn.ConnectionState().TLS.NegotiatedProtocol
@@ -139,6 +146,8 @@ func (l *quicListener) Run() error {
 		ln, ok := l.protocols[proto]
 		if !ok {
 			l.protocolsMu.Unlock()
+			close(l.running)
+			l.transport.DecreaseCount()
 			return fmt.Errorf("negotiated unknown protocol: %s", proto)
 		}
 		ln.ln.add(conn)

go-libp2p/p2p/transport/webrtc/udpmux/mux.go

@@ -82,8 +82,8 @@ func NewUDPMux(socket net.PacketConn) *UDPMux {
 func (mux *UDPMux) Start() {
 	mux.wg.Add(1)
 	go func() {
-		defer mux.wg.Done()
 		mux.readLoop()
+		mux.wg.Done()
 	}()
 }
 
@@ -264,7 +264,6 @@ func (mux *UDPMux) RemoveConnByUfrag(ufrag string) {
 	}
 
 	mux.mx.Lock()
-	defer mux.mx.Unlock()
 
 	for _, isIPv6 := range [...]bool{true, false} {
 		key := ufragConnKey{ufrag: ufrag, isIPv6: isIPv6}
@@ -276,17 +275,18 @@ func (mux *UDPMux) RemoveConnByUfrag(ufrag string) {
 			delete(mux.ufragAddrMap, key)
 		}
 	}
+	mux.mx.Unlock()
 }
 
 func (mux *UDPMux) getOrCreateConn(ufrag string, isIPv6 bool, _ *UDPMux, addr net.Addr) (created bool, _ *muxedConnection) {
 	key := ufragConnKey{ufrag: ufrag, isIPv6: isIPv6}
 
 	mux.mx.Lock()
-	defer mux.mx.Unlock()
 
 	if conn, ok := mux.ufragMap[key]; ok {
 		mux.addrMap[addr.String()] = conn
 		mux.ufragAddrMap[key] = append(mux.ufragAddrMap[key], addr)
+		mux.mx.Unlock()
 		return false, conn
 	}
 
@@ -294,5 +294,6 @@ func (mux *UDPMux) getOrCreateConn(ufrag string, isIPv6 bool, _ *UDPMux, addr ne
 	mux.ufragMap[key] = conn
 	mux.addrMap[addr.String()] = conn
 	mux.ufragAddrMap[key] = append(mux.ufragAddrMap[key], addr)
+	mux.mx.Unlock()
 	return true, conn
 }

go-libp2p/p2p/transport/websocket/conn.go

@@ -40,10 +40,10 @@ func NewConn(raw *ws.Conn, secure bool) *Conn {
 
 func (c *Conn) Read(b []byte) (int, error) {
 	c.readLock.Lock()
-	defer c.readLock.Unlock()
 
 	if c.reader == nil {
 		if err := c.prepNextReader(); err != nil {
+			c.readLock.Unlock()
 			return 0, err
 		}
 	}
@@ -55,15 +55,18 @@ func (c *Conn) Read(b []byte) (int, error) {
 			c.reader = nil
 
 			if n > 0 {
+				c.readLock.Unlock()
 				return n, nil
 			}
 
 			if err := c.prepNextReader(); err != nil {
+				c.readLock.Unlock()
 				return 0, err
 			}
 
 			// explicitly looping
 		default:
+			c.readLock.Unlock()
 			return n, err
 		}
 	}
@@ -90,12 +93,13 @@ func (c *Conn) prepNextReader() error {
 
 func (c *Conn) Write(b []byte) (n int, err error) {
 	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
 
 	if err := c.Conn.WriteMessage(c.DefaultMessageType, b); err != nil {
+		c.writeLock.Unlock()
 		return 0, err
 	}
 
+	c.writeLock.Unlock()
 	return len(b), nil
 }
 
@@ -148,9 +152,9 @@ func (c *Conn) SetWriteDeadline(t time.Time) error {
 	// deadline.
 
 	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
+	err := c.Conn.SetWriteDeadline(t)
-
+	c.writeLock.Unlock()
-	return c.Conn.SetWriteDeadline(t)
+	return err
 }
 
 type capableConn struct {

go-libp2p/p2p/transport/websocket/listener.go

@@ -93,12 +93,12 @@ func newListener(a ma.Multiaddr, tlsConf *tls.Config) (*listener, error) {
 }
 
 func (l *listener) serve() {
-	defer close(l.closed)
 	if !l.isWss {
 		l.server.Serve(l.nl)
 	} else {
 		l.server.ServeTLS(l.nl, "", "")
 	}
+	close(l.closed)
 }
 
 func (l *listener) ServeHTTP(w http.ResponseWriter, r *http.Request) {

node/p2p/blossomsub.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/hex"
 	"fmt"
+	"math/bits"
 	"sync"
 	"time"
 
@@ -17,8 +18,12 @@ import (
 	"github.com/libp2p/go-libp2p/core/peer"
 	"github.com/libp2p/go-libp2p/p2p/discovery/routing"
 	"github.com/libp2p/go-libp2p/p2p/discovery/util"
+	rcmgr "github.com/libp2p/go-libp2p/p2p/host/resource-manager"
 	"github.com/libp2p/go-libp2p/p2p/net/connmgr"
+	ma "github.com/multiformats/go-multiaddr"
+	madns "github.com/multiformats/go-multiaddr-dns"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
 	"go.uber.org/zap"
 	blossomsub "source.quilibrium.com/quilibrium/monorepo/go-libp2p-blossomsub"
 	"source.quilibrium.com/quilibrium/monorepo/go-libp2p-blossomsub/pb"
@@ -111,6 +116,23 @@ func NewBlossomSub(
 		}
 	}
 
+	defaultBootstrapPeers := append([]string{}, p2pConfig.BootstrapPeers...)
+
+	if p2pConfig.Network == 0 {
+		defaultBootstrapPeers = config.BootstrapPeers
+	}
+
+	bootstrappers := []peer.AddrInfo{}
+
+	for _, peerAddr := range defaultBootstrapPeers {
+		peerinfo, err := peer.AddrInfoFromString(peerAddr)
+		if err != nil {
+			panic(err)
+		}
+
+		bootstrappers = append(bootstrappers, *peerinfo)
+	}
+
 	var privKey crypto.PrivKey
 	if p2pConfig.PeerPrivKey != "" {
 		peerPrivKey, err := hex.DecodeString(p2pConfig.PeerPrivKey)
@@ -136,7 +158,17 @@ func NewBlossomSub(
 		if err != nil {
 			panic(err)
 		}
+
+		rm, err := resourceManager(
+			p2pConfig.HighWatermarkConnections,
+			bootstrappers,
+		)
+		if err != nil {
+			panic(err)
+		}
+
 		opts = append(opts, libp2p.ConnectionManager(cm))
+		opts = append(opts, libp2p.ResourceManager(rm))
 	}
 
 	bs := &BlossomSub{
@@ -156,7 +188,14 @@ func NewBlossomSub(
 
 	logger.Info("established peer id", zap.String("peer_id", h.ID().String()))
 
-	kademliaDHT := initDHT(ctx, p2pConfig, logger, h, isBootstrapPeer)
+	kademliaDHT := initDHT(
+		ctx,
+		p2pConfig,
+		logger,
+		h,
+		isBootstrapPeer,
+		bootstrappers,
+	)
 	routingDiscovery := routing.NewRoutingDiscovery(kademliaDHT)
 	util.Advertise(ctx, routingDiscovery, getNetworkNamespace(p2pConfig.Network))
 
@@ -223,6 +262,96 @@ func NewBlossomSub(
 	return bs
 }
 
+// adjusted from Lotus' reference implementation, addressing
+// https://github.com/libp2p/go-libp2p/issues/1640
+func resourceManager(highWatermark uint, bootstrappers []peer.AddrInfo) (
+	network.ResourceManager,
+	error,
+) {
+	defaultLimits := rcmgr.DefaultLimits
+
+	libp2p.SetDefaultServiceLimits(&defaultLimits)
+
+	defaultLimits.SystemBaseLimit.Memory = 1 << 28
+	defaultLimits.SystemLimitIncrease.Memory = 1 << 28
+	defaultLimitConfig := defaultLimits.AutoScale()
+
+	changes := rcmgr.PartialLimitConfig{}
+
+	if defaultLimitConfig.ToPartialLimitConfig().System.Memory > 2<<30 {
+		changes.System.Memory = 2 << 30
+	}
+
+	maxconns := uint(highWatermark)
+	if rcmgr.LimitVal(3*maxconns) > defaultLimitConfig.
+		ToPartialLimitConfig().System.ConnsInbound {
+		changes.System.ConnsInbound = rcmgr.LimitVal(1 << bits.Len(3*maxconns))
+		changes.System.ConnsOutbound = rcmgr.LimitVal(1 << bits.Len(3*maxconns))
+		changes.System.Conns = rcmgr.LimitVal(1 << bits.Len(6*maxconns))
+		changes.System.StreamsInbound = rcmgr.LimitVal(1 << bits.Len(36*maxconns))
+		changes.System.StreamsOutbound = rcmgr.LimitVal(1 << bits.Len(216*maxconns))
+		changes.System.Streams = rcmgr.LimitVal(1 << bits.Len(216*maxconns))
+
+		if rcmgr.LimitVal(3*maxconns) > defaultLimitConfig.
+			ToPartialLimitConfig().System.FD {
+			changes.System.FD = rcmgr.LimitVal(1 << bits.Len(3*maxconns))
+		}
+
+		changes.ServiceDefault.StreamsInbound = rcmgr.LimitVal(
+			1 << bits.Len(12*maxconns),
+		)
+		changes.ServiceDefault.StreamsOutbound = rcmgr.LimitVal(
+			1 << bits.Len(48*maxconns),
+		)
+		changes.ServiceDefault.Streams = rcmgr.LimitVal(1 << bits.Len(48*maxconns))
+		changes.ProtocolDefault.StreamsInbound = rcmgr.LimitVal(
+			1 << bits.Len(12*maxconns),
+		)
+		changes.ProtocolDefault.StreamsOutbound = rcmgr.LimitVal(
+			1 << bits.Len(48*maxconns),
+		)
+		changes.ProtocolDefault.Streams = rcmgr.LimitVal(1 << bits.Len(48*maxconns))
+	}
+
+	changedLimitConfig := changes.Build(defaultLimitConfig)
+
+	limiter := rcmgr.NewFixedLimiter(changedLimitConfig)
+
+	str, err := rcmgr.NewStatsTraceReporter()
+	if err != nil {
+		return nil, errors.Wrap(err, "resource manager")
+	}
+
+	rcmgr.MustRegisterWith(prometheus.DefaultRegisterer)
+
+	// Metrics
+	opts := append(
+		[]rcmgr.Option{},
+		rcmgr.WithTraceReporter(str),
+	)
+
+	resolver := madns.DefaultResolver
+	var bootstrapperMaddrs []ma.Multiaddr
+	for _, pi := range bootstrappers {
+		for _, addr := range pi.Addrs {
+			resolved, err := resolver.Resolve(context.Background(), addr)
+			if err != nil {
+				continue
+			}
+			bootstrapperMaddrs = append(bootstrapperMaddrs, resolved...)
+		}
+	}
+
+	opts = append(opts, rcmgr.WithAllowlistedMultiaddrs(bootstrapperMaddrs))
+
+	mgr, err := rcmgr.NewResourceManager(limiter, opts...)
+	if err != nil {
+		return nil, errors.Wrap(err, "resource manager")
+	}
+
+	return mgr, nil
+}
+
 func (b *BlossomSub) PublishToBitmask(bitmask []byte, data []byte) error {
 	return b.ps.Publish(b.ctx, bitmask, data)
 }
@@ -303,26 +432,11 @@ func initDHT(
 	logger *zap.Logger,
 	h host.Host,
 	isBootstrapPeer bool,
+	bootstrappers []peer.AddrInfo,
 ) *dht.IpfsDHT {
 	logger.Info("establishing dht")
 	var kademliaDHT *dht.IpfsDHT
 	var err error
-	defaultBootstrapPeers := append([]string{}, p2pConfig.BootstrapPeers...)
-
-	if p2pConfig.Network == 0 {
-		defaultBootstrapPeers = config.BootstrapPeers
-	}
-
-	bootstrappers := []peer.AddrInfo{}
-
-	for _, peerAddr := range defaultBootstrapPeers {
-		peerinfo, err := peer.AddrInfoFromString(peerAddr)
-		if err != nil {
-			panic(err)
-		}
-
-		bootstrappers = append(bootstrappers, *peerinfo)
-	}
 
 	if isBootstrapPeer {
 		kademliaDHT, err = dht.New(