Fix double close in logger

client/firewall/uspfilter/log/log.go

@@ -48,6 +48,7 @@ type Logger struct {
 	level     atomic.Uint32
 	buffer    *ringBuffer
 	shutdown  chan struct{}
+	closeOnce sync.Once
 	wg        sync.WaitGroup
 
 	// Reusable buffer pool for formatting messages
@@ -170,9 +171,12 @@ func (l *Logger) worker() {
 
 // Stop gracefully shuts down the logger
 func (l *Logger) Stop(ctx context.Context) error {
-	close(l.shutdown)
-
 	done := make(chan struct{})
+
+	l.closeOnce.Do(func() {
+		close(l.shutdown)
+	})
+
 	go func() {
 		l.wg.Wait()
 		close(done)