From a9821961754712289d9e63368caf47709dc48b86 Mon Sep 17 00:00:00 2001
From: Sepherosa Ziehau <sephe@dragonflybsd.org>
Date: Sun, 12 Feb 2017 22:19:52 +0800
Subject: [PATCH] net: Make sure that local variable is really used.

---
 sys/net/if.c           | 7 ++++++-
 sys/net/if_ethersubr.c | 2 ++
 sys/net/pfil.c         | 2 ++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/sys/net/if.c b/sys/net/if.c
index db24f7bcb4..8ffb453133 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -3554,8 +3554,13 @@ ifnet_array_del(struct ifnet *ifp, const struct ifnet_array *old_arr)
 const struct ifnet_array *
 ifnet_array_get(void)
 {
+	const struct ifnet_array *ret;
+
 	KASSERT(curthread->td_type == TD_TYPE_NETISR, ("not in netisr"));
-	return ifnet_array;
+	ret = ifnet_array;
+	/* Make sure 'ret' is really used. */
+	cpu_ccfence();
+	return (ret);
 }
 
 int
diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index 71dc0e4db6..2c77eb1ad1 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1051,6 +1051,8 @@ post_stats:
 		void (*vlan_input_func)(struct mbuf *);
 
 		vlan_input_func = vlan_input_p;
+		/* Make sure 'vlan_input_func' is really used. */
+		cpu_ccfence();
 		if (vlan_input_func != NULL) {
 			vlan_input_func(m);
 		} else {
diff --git a/sys/net/pfil.c b/sys/net/pfil.c
index a23654c34a..34f4791e1f 100644
--- a/sys/net/pfil.c
+++ b/sys/net/pfil.c
@@ -106,6 +106,8 @@ pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
 	else
 		return 0; /* XXX panic? */
 
+	/* Make sure 'list' is really used. */
+	cpu_ccfence();
 	TAILQ_FOREACH(pfh, list, pfil_link) {
 		if (pfh->pfil_func != NULL) {
 			rv = pfh->pfil_func(pfh->pfil_arg, &m, ifp, dir);
-- 
2.41.0