From 16cf279f8c5769e2d9824a5a2ac71da1c331d29b Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Mon, 5 Sep 2022 10:52:47 +0300
Subject: [PATCH] fix inconsistent locking of mutexes by holding the stateLock
 for shorter

---
 stream.go | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/stream.go b/stream.go
index 9175268..c3bd2d1 100644
--- a/stream.go
+++ b/stream.go
@@ -385,22 +385,24 @@ func (s *Stream) cleanup() {
 // based on set flags, if any. Lock must be held
 func (s *Stream) processFlags(flags uint16) {
 	// Close the stream without holding the state lock
-	closeStream := false
+	var closeStream bool
 	defer func() {
 		if closeStream {
 			s.cleanup()
 		}
 	}()
 
-	s.stateLock.Lock()
-	defer s.stateLock.Unlock()
 	if flags&flagACK == flagACK {
+		s.stateLock.Lock()
 		if s.state == streamSYNSent {
 			s.state = streamEstablished
 		}
+		s.stateLock.Unlock()
 		s.session.establishStream(s.id)
 	}
 	if flags&flagFIN == flagFIN {
+		var notify bool
+		s.stateLock.Lock()
 		if s.readState == halfOpen {
 			s.readState = halfClosed
 			if s.writeState != halfOpen {
@@ -408,10 +410,15 @@ func (s *Stream) processFlags(flags uint16) {
 				closeStream = true
 				s.state = streamFinished
 			}
+			notify = true
+		}
+		s.stateLock.Unlock()
+		if notify {
 			s.notifyWaiting()
 		}
 	}
 	if flags&flagRST == flagRST {
+		s.stateLock.Lock()
 		if s.readState == halfOpen {
 			s.readState = halfReset
 		}
@@ -419,6 +426,7 @@ func (s *Stream) processFlags(flags uint16) {
 			s.writeState = halfReset
 		}
 		s.state = streamFinished
+		s.stateLock.Unlock()
 		closeStream = true
 		s.notifyWaiting()
 	}