From 01ae73c5eb2d059ceb1d1734f72282cefb78d440 Mon Sep 17 00:00:00 2001
From: dlg <dlg@openbsd.org>
Date: Fri, 9 Jul 2021 01:22:05 +0000
Subject: [PATCH] ifq_hdatalen can return 0 if ifq_empty is true, which avoids
 locks.

---
 sys/net/ifq.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/net/ifq.c b/sys/net/ifq.c
index 51eaaf44343..d61e5934624 100644
--- a/sys/net/ifq.c
+++ b/sys/net/ifq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ifq.c,v 1.43 2021/02/20 04:37:26 dlg Exp $ */
+/*	$OpenBSD: ifq.c,v 1.44 2021/07/09 01:22:05 dlg Exp $ */
 
 /*
  * Copyright (c) 2015 David Gwynne <dlg@openbsd.org>
@@ -500,6 +500,9 @@ ifq_hdatalen(struct ifqueue *ifq)
 	struct mbuf *m;
 	int len = 0;
 
+	if (ifq_empty(ifq))
+		return (0);
+
 	m = ifq_deq_begin(ifq);
 	if (m != NULL) {
 		len = m->m_pkthdr.len;
-- 
2.20.1