From ccd5fced8333f227addea641ab17fa3c82598764 Mon Sep 17 00:00:00 2001
From: Csaba Kiraly <csaba.kiraly@gmail.com>
Date: Mon, 22 Jun 2026 17:55:50 +0200
Subject: [PATCH] eth/txtracker: make Stop safe before Start and idempotent

---
 eth/txtracker/tracker.go | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/eth/txtracker/tracker.go b/eth/txtracker/tracker.go
index 93797cad9d..02da6f5a88 100644
--- a/eth/txtracker/tracker.go
+++ b/eth/txtracker/tracker.go
@@ -80,9 +80,10 @@ type Tracker struct {
 	headCh       chan core.ChainHeadEvent
 	sub          event.Subscription
 
-	quit chan struct{}
-	step chan struct{} // test sync: sent after each event is processed
-	wg   sync.WaitGroup
+	quit     chan struct{}
+	stopOnce sync.Once
+	step     chan struct{} // test sync: sent after each event is processed
+	wg       sync.WaitGroup
 }
 
 // New creates a new tracker.
@@ -118,8 +119,12 @@ func (t *Tracker) NotifyPeerDrop(peer string) {
 
 // Stop shuts down the tracker.
 func (t *Tracker) Stop() {
-	t.sub.Unsubscribe()
-	close(t.quit)
+	t.stopOnce.Do(func() {
+		if t.sub != nil {
+			t.sub.Unsubscribe()
+		}
+		close(t.quit)
+	})
 	t.wg.Wait()
 }