From: Josh Bleecher Snyder <josh@tailscale.com>
Date: Sat, 19 Dec 2020 00:32:46 +0000 (-0800)
Subject: device: call wg.Add outside the goroutine
X-Git-Tag: 0.0.20210212~113
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b42e32047d16cc4389ef63550e525c7b08320172;p=thirdparty%2Fwireguard-go.git

device: call wg.Add outside the goroutine

One of the first rules of WaitGroups is that you call wg.Add
outside of a goroutine, not inside it. Fix this embarrassing mistake.

This prevents an extremely rare race condition (2 per 100,000 runs)
which could occur when attempting to start a new peer
concurrently with shutting down a device.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
---

diff --git a/device/peer.go b/device/peer.go
index 8006b9f..ac85c94 100644
--- a/device/peer.go
+++ b/device/peer.go
@@ -213,6 +213,8 @@ func (peer *Peer) Start() {
 
 	// wait for routines to start
 
+	// RoutineNonce writes to the encryption queue; keep it alive until we are done.
+	device.queue.encryption.wg.Add(1)
 	go peer.RoutineNonce()
 	go peer.RoutineSequentialSender()
 	go peer.RoutineSequentialReceiver()
diff --git a/device/send.go b/device/send.go
index c75d23e..55df4b3 100644
--- a/device/send.go
+++ b/device/send.go
@@ -352,9 +352,6 @@ func (peer *Peer) RoutineNonce() {
 	device := peer.device
 	logDebug := device.log.Debug
 
-	// We write to the encryption queue; keep it alive until we are done.
-	device.queue.encryption.wg.Add(1)
-
 	flush := func() {
 		for {
 			select {