From 317fc6b77d946253ec00f0b536d253fb4781a3de Mon Sep 17 00:00:00 2001
From: mvs <mvs@openbsd.org>
Date: Sun, 26 Jun 2022 22:51:58 +0000
Subject: [PATCH] Mark `pipex_enable' as atomic. We never check `pipex_enable'
 within (*if_qstart)() and we don't worry it's not serialized with the rest of
 output path. Also we will process already enqueued pipex(4) packets
 regardless on `pipex_enable' state.

Use the local copy of `pipex_enable' within pppx_if_output(), otherwise we
loose consistency.

pointed and ok by bluhm@
---
 sys/net/if_pppx.c | 10 ++++++----
 sys/net/pipex.c   |  4 ++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/sys/net/if_pppx.c b/sys/net/if_pppx.c
index 0aaaedc038f..b103addd284 100644
--- a/sys/net/if_pppx.c
+++ b/sys/net/if_pppx.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_pppx.c,v 1.116 2022/06/26 15:50:21 mvs Exp $ */
+/*	$OpenBSD: if_pppx.c,v 1.117 2022/06/26 22:51:58 mvs Exp $ */
 
 /*
  * Copyright (c) 2010 Claudio Jeker <claudio@openbsd.org>
@@ -817,7 +817,9 @@ pppx_if_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	struct pppx_if *pxi = (struct pppx_if *)ifp->if_softc;
 	struct pppx_hdr *th;
 	int error = 0;
-	int proto;
+	int pipex_enable_local, proto;
+
+	pipex_enable_local = atomic_load_int(&pipex_enable);
 
 	NET_ASSERT_LOCKED();
 
@@ -831,7 +833,7 @@ pppx_if_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	if (ifp->if_bpf)
 		bpf_mtap_af(ifp->if_bpf, dst->sa_family, m, BPF_DIRECTION_OUT);
 #endif
-	if (pipex_enable) {
+	if (pipex_enable_local) {
 		switch (dst->sa_family) {
 #ifdef INET6
 		case AF_INET6:
@@ -856,7 +858,7 @@ pppx_if_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	}
 	*mtod(m, int *) = proto;
 
-	if (pipex_enable)
+	if (pipex_enable_local)
 		error = if_enqueue(ifp, m);
 	else {
 		M_PREPEND(m, sizeof(struct pppx_hdr), M_DONTWAIT);
diff --git a/sys/net/pipex.c b/sys/net/pipex.c
index 33e5e2351ef..393a7d563d7 100644
--- a/sys/net/pipex.c
+++ b/sys/net/pipex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pipex.c,v 1.140 2022/06/26 21:29:34 mvs Exp $ */
+/*	$OpenBSD: pipex.c,v 1.141 2022/06/26 22:51:58 mvs Exp $ */
 
 /*-
  * Copyright (c) 2009 Internet Initiative Japan Inc.
@@ -94,7 +94,7 @@ struct pool mppe_key_pool;
  *       L       pipex_list_mtx
  */
 
-int	pipex_enable = 0;			/* [N] */
+int	pipex_enable = 0;			/* [A] */
 struct pipex_hash_head
     pipex_session_list,				/* [L] master session list */
     pipex_close_wait_list,			/* [L] expired session list */
-- 
2.20.1