xfrm: slightly optimise xfrm_input

Check x->km.state with XFRM_STATE_ACQ only when state is not
XFRM_STAT_VALID, not everytime
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_input.c

@@ -239,13 +239,13 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 		skb->sp->xvec[skb->sp->len++] = x;
 
 		spin_lock(&x->lock);
-		if (unlikely(x->km.state == XFRM_STATE_ACQ)) {
-			XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
-			goto drop_unlock;
-		}
 
 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
-			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEINVALID);
+			if (x->km.state == XFRM_STATE_ACQ)
+				XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
+			else
+				XFRM_INC_STATS(net,
+					       LINUX_MIB_XFRMINSTATEINVALID);
 			goto drop_unlock;
 		}