net sched actions police: peg drop stats for conforming traffic

setting conforming action to drop is a valid policy.
When it is set we need to at least see the stats indicating it
for debugging.
Signed-off-by: Roman Mashak <mrv@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_police.c

@@ -249,6 +249,8 @@ static int tcf_act_police(struct sk_buff *skb, const struct tc_action *a,
 			police->tcfp_t_c = now;
 			police->tcfp_toks = toks;
 			police->tcfp_ptoks = ptoks;
+			if (police->tcfp_result == TC_ACT_SHOT)
+				police->tcf_qstats.drops++;
 			spin_unlock(&police->tcf_lock);
 			return police->tcfp_result;
 		}