From 08cde9886916bacd8ec9376677005abb027c33c3 Mon Sep 17 00:00:00 2001
From: Elle Mouton <elle.mouton@gmail.com>
Date: Wed, 22 Mar 2023 11:35:25 +0200
Subject: [PATCH] wtclient: add mutex locking in perUpdate

Lock the `backupMu` when accessing `c.chanCommitHeights` in the `New`
function. It is not strictly necessary right now but good to add it so
that there is no accidental oversight if the `perUpdate` method is ever
extracted and reused in future.
---
 watchtower/wtclient/client.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/watchtower/wtclient/client.go b/watchtower/wtclient/client.go
index fe4b18648..8a2597980 100644
--- a/watchtower/wtclient/client.go
+++ b/watchtower/wtclient/client.go
@@ -386,6 +386,9 @@ func New(config *Config) (*TowerClient, error) {
 			return
 		}
 
+		c.backupMu.Lock()
+		defer c.backupMu.Unlock()
+
 		// Take the highest commit height found in the session's acked
 		// updates.
 		height, ok := c.chanCommitHeights[chanID]