From c683151962301f5e3ddfb765ea1fc011e415e08c Mon Sep 17 00:00:00 2001
From: mpi <mpi@openbsd.org>
Date: Mon, 29 May 2017 06:08:21 +0000
Subject: [PATCH] Do not try to grab the NET_LOCK() while holding an ifp
 reference.

Fix a deadlock with a thread trying to detach the corresponding interface.

ok sashan@, bluhm@
---
 sys/net/if.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/sys/net/if.c b/sys/net/if.c
index 8532743929e..d519ddcfeba 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if.c,v 1.499 2017/05/28 12:51:33 yasuoka Exp $	*/
+/*	$OpenBSD: if.c,v 1.500 2017/05/29 06:08:21 mpi Exp $	*/
 /*	$NetBSD: if.c,v 1.35 1996/05/07 05:26:04 thorpej Exp $	*/
 
 /*
@@ -1559,15 +1559,14 @@ if_linkstate_task(void *xifidx)
 	struct ifnet *ifp;
 	int s;
 
-	ifp = if_get(ifidx);
-	if (ifp == NULL)
-		return;
-
 	NET_LOCK(s);
-	if_linkstate(ifp);
-	NET_UNLOCK(s);
 
+	ifp = if_get(ifidx);
+	if (ifp != NULL)
+		if_linkstate(ifp);
 	if_put(ifp);
+
+	NET_UNLOCK(s);
 }
 
 void
-- 
2.20.1