xfrm: store xfrm_mode directly, not its address

This structure is now only 4 bytes, so its more efficient
to cache a copy rather than its address.

No significant size difference in allmodconfig vmlinux.

With non-modular kernel that has all XFRM options enabled, this
series reduces vmlinux image size by ~11kb. All xfrm_mode
indirections are gone and all modes are built-in.

before (ipsec-next master):
    text      data      bss         dec   filename
21071494   7233140 11104324    39408958   vmlinux.master

after this series:
21066448   7226772 11104324    39397544   vmlinux.patched

With allmodconfig kernel, the size increase is only 362 bytes,
even all the xfrm config options removed in this series are
modular.

before:
    text      data     bss      dec   filename
15731286   6936912 4046908 26715106   vmlinux.master

after this series:
15731492   6937068  4046908  26715468 vmlinux

Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index 4fc49db..b9f1185 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -273,7 +273,7 @@ static int xfrmi_rcv_cb(struct sk_buff *skb, int err)
 	xnet = !net_eq(xi->net, dev_net(skb->dev));
 
 	if (xnet) {
-		inner_mode = x->inner_mode;
+		inner_mode = &x->inner_mode;
 
 		if (x->sel.family == AF_UNSPEC) {
 			inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);