From fe23506471e8a7a94b0615ad5178be99a7e60c90 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Fri, 9 Apr 2021 11:13:42 -0700
Subject: [PATCH] ipn/ipnlocal: avoid unneeded initPeerAPIListener work if no
 changes

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
---
 ipn/ipnlocal/local.go | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/ipn/ipnlocal/local.go b/ipn/ipnlocal/local.go
index c6031209a..fc3396132 100644
--- a/ipn/ipnlocal/local.go
+++ b/ipn/ipnlocal/local.go
@@ -1600,6 +1600,20 @@ func (b *LocalBackend) initPeerAPIListener() {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
+	if len(b.netMap.Addresses) == len(b.peerAPIListeners) {
+		allSame := true
+		for i, pln := range b.peerAPIListeners {
+			if pln.ip != b.netMap.Addresses[i].IP {
+				allSame = false
+				break
+			}
+		}
+		if allSame {
+			// Nothing to do.
+			return
+		}
+	}
+
 	b.peerAPIServer = nil
 	for _, pln := range b.peerAPIListeners {
 		pln.Close()