From 76686f230b4f4ebbb39d53f974c475f1e38eb69b Mon Sep 17 00:00:00 2001
From: Spike Curtis <spike@coder.com>
Date: Thu, 30 Nov 2023 12:21:18 +0400
Subject: [PATCH] fix: prevent connIO from panicking in race between Close and
 Enqueue

---
 enterprise/tailnet/connio.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/enterprise/tailnet/connio.go b/enterprise/tailnet/connio.go
index 9454279adcb4c..83c1d8a2b9c3c 100644
--- a/enterprise/tailnet/connio.go
+++ b/enterprise/tailnet/connio.go
@@ -197,9 +197,8 @@ func (c *connIO) UniqueID() uuid.UUID {
 func (c *connIO) Enqueue(resp *proto.CoordinateResponse) error {
 	atomic.StoreInt64(&c.lastWrite, time.Now().Unix())
 	c.mu.Lock()
-	closed := c.closed
-	c.mu.Unlock()
-	if closed {
+	defer c.mu.Unlock()
+	if c.closed {
 		return xerrors.New("connIO closed")
 	}
 	select {