/*
   * net/sched/police.c	Input police filter.
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   *
   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   * 		J Hadi Salim (action changes)
   */

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/string.h>

  #include <linux/errno.h>

  #include <linux/skbuff.h>

  #include <linux/rtnetlink.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <net/act_api.h>

  #include <net/netlink.h>

  #define L2T(p, L)   qdisc_l2t((p)->tcfp_R_tab, L)
  #define L2T_P(p, L) qdisc_l2t((p)->tcfp_P_tab, L)

  #define POL_TAB_MASK     15
  static struct tcf_common *tcf_police_ht[POL_TAB_MASK + 1];
  static u32 police_idx_gen;
  static DEFINE_RWLOCK(police_lock);

  static struct tcf_hashinfo police_hash_info = {
  	.htab	=	tcf_police_ht,
  	.hmask	=	POL_TAB_MASK,
  	.lock	=	&police_lock,
  };

  /* old policer structure from before tc actions */

  struct tc_police_compat {

  	u32			index;
  	int			action;
  	u32			limit;
  	u32			burst;
  	u32			mtu;
  	struct tc_ratespec	rate;
  	struct tc_ratespec	peakrate;
  };

  /* Each policer is serialized by its individual spinlock */

  static int tcf_act_police_walker(struct sk_buff *skb, struct netlink_callback *cb,

  			      int type, struct tc_action *a)

  {

  	struct tcf_common *p;

  	int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;

  	struct nlattr *nest;

  	read_lock_bh(&police_lock);

  
  	s_i = cb->args[0];

  	for (i = 0; i < (POL_TAB_MASK + 1); i++) {
  		p = tcf_police_ht[tcf_hash(i, POL_TAB_MASK)];

  		for (; p; p = p->tcfc_next) {

  			index++;
  			if (index < s_i)
  				continue;
  			a->priv = p;
  			a->order = index;

  			nest = nla_nest_start(skb, a->order);
  			if (nest == NULL)
  				goto nla_put_failure;

  			if (type == RTM_DELACTION)
  				err = tcf_action_dump_1(skb, a, 0, 1);
  			else
  				err = tcf_action_dump_1(skb, a, 0, 0);
  			if (err < 0) {
  				index--;

  				nla_nest_cancel(skb, nest);

  				goto done;
  			}

  			nla_nest_end(skb, nest);

  			n_i++;
  		}
  	}
  done:

  	read_unlock_bh(&police_lock);

  	if (n_i)
  		cb->args[0] += n_i;
  	return n_i;

  nla_put_failure:

  	nla_nest_cancel(skb, nest);

  	goto done;
  }

  static void tcf_police_destroy(struct tcf_police *p)

  {

  	unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK);
  	struct tcf_common **p1p;

  	for (p1p = &tcf_police_ht[h]; *p1p; p1p = &(*p1p)->tcfc_next) {
  		if (*p1p == &p->common) {

  			write_lock_bh(&police_lock);

  			*p1p = p->tcf_next;

  			write_unlock_bh(&police_lock);

  			gen_kill_estimator(&p->tcf_bstats,
  					   &p->tcf_rate_est);

  			if (p->tcfp_R_tab)
  				qdisc_put_rtab(p->tcfp_R_tab);
  			if (p->tcfp_P_tab)
  				qdisc_put_rtab(p->tcfp_P_tab);

  			/*
  			 * gen_estimator est_timer() might access p->tcf_lock
  			 * or bstats, wait a RCU grace period before freeing p
  			 */

  			kfree_rcu(p, tcf_rcu);

  			return;
  		}
  	}

  	WARN_ON(1);

  }

  static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
  	[TCA_POLICE_RATE]	= { .len = TC_RTAB_SIZE },
  	[TCA_POLICE_PEAKRATE]	= { .len = TC_RTAB_SIZE },
  	[TCA_POLICE_AVRATE]	= { .type = NLA_U32 },
  	[TCA_POLICE_RESULT]	= { .type = NLA_U32 },
  };

  static int tcf_act_police_locate(struct nlattr *nla, struct nlattr *est,

  				 struct tc_action *a, int ovr, int bind)

  {

  	unsigned int h;

  	int ret = 0, err;

  	struct nlattr *tb[TCA_POLICE_MAX + 1];

  	struct tc_police *parm;

  	struct tcf_police *police;

  	struct qdisc_rate_table *R_tab = NULL, *P_tab = NULL;

  	int size;

  	if (nla == NULL)

  		return -EINVAL;

  	err = nla_parse_nested(tb, TCA_POLICE_MAX, nla, police_policy);

  	if (err < 0)
  		return err;

  	if (tb[TCA_POLICE_TBF] == NULL)

  		return -EINVAL;

  	size = nla_len(tb[TCA_POLICE_TBF]);

  	if (size != sizeof(*parm) && size != sizeof(struct tc_police_compat))

  		return -EINVAL;

  	parm = nla_data(tb[TCA_POLICE_TBF]);

  	if (parm->index) {
  		struct tcf_common *pc;
  
  		pc = tcf_hash_lookup(parm->index, &police_hash_info);
  		if (pc != NULL) {
  			a->priv = pc;
  			police = to_police(pc);
  			if (bind) {
  				police->tcf_bindcnt += 1;
  				police->tcf_refcnt += 1;
  			}
  			if (ovr)
  				goto override;
  			return ret;

  		}

  	}

  	police = kzalloc(sizeof(*police), GFP_KERNEL);
  	if (police == NULL)

  		return -ENOMEM;

  	ret = ACT_P_CREATED;

  	police->tcf_refcnt = 1;
  	spin_lock_init(&police->tcf_lock);

  	if (bind)

  		police->tcf_bindcnt = 1;

  override:
  	if (parm->rate.rate) {
  		err = -ENOMEM;

  		R_tab = qdisc_get_rtab(&parm->rate, tb[TCA_POLICE_RATE]);

  		if (R_tab == NULL)
  			goto failure;

  		if (parm->peakrate.rate) {
  			P_tab = qdisc_get_rtab(&parm->peakrate,

  					       tb[TCA_POLICE_PEAKRATE]);

  			if (P_tab == NULL)

  				goto failure;

  		}
  	}

  	spin_lock_bh(&police->tcf_lock);

  	if (est) {
  		err = gen_replace_estimator(&police->tcf_bstats,
  					    &police->tcf_rate_est,
  					    &police->tcf_lock, est);
  		if (err)
  			goto failure_unlock;

  	} else if (tb[TCA_POLICE_AVRATE] &&
  		   (ret == ACT_P_CREATED ||
  		    !gen_estimator_active(&police->tcf_bstats,
  					  &police->tcf_rate_est))) {
  		err = -EINVAL;
  		goto failure_unlock;

  	}
  
  	/* No failure allowed after this point */

  	if (R_tab != NULL) {

  		qdisc_put_rtab(police->tcfp_R_tab);
  		police->tcfp_R_tab = R_tab;

  	}
  	if (P_tab != NULL) {

  		qdisc_put_rtab(police->tcfp_P_tab);
  		police->tcfp_P_tab = P_tab;

  	}

  	if (tb[TCA_POLICE_RESULT])

  		police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);

  	police->tcfp_toks = police->tcfp_burst = parm->burst;
  	police->tcfp_mtu = parm->mtu;
  	if (police->tcfp_mtu == 0) {
  		police->tcfp_mtu = ~0;
  		if (police->tcfp_R_tab)
  			police->tcfp_mtu = 255<<police->tcfp_R_tab->rate.cell_log;

  	}

  	if (police->tcfp_P_tab)
  		police->tcfp_ptoks = L2T_P(police, police->tcfp_mtu);
  	police->tcf_action = parm->action;

  	if (tb[TCA_POLICE_AVRATE])

  		police->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);

  	spin_unlock_bh(&police->tcf_lock);

  	if (ret != ACT_P_CREATED)
  		return ret;

  	police->tcfp_t_c = psched_get_time();

  	police->tcf_index = parm->index ? parm->index :
  		tcf_hash_new_index(&police_idx_gen, &police_hash_info);
  	h = tcf_hash(police->tcf_index, POL_TAB_MASK);

  	write_lock_bh(&police_lock);

  	police->tcf_next = tcf_police_ht[h];
  	tcf_police_ht[h] = &police->common;

  	write_unlock_bh(&police_lock);

  	a->priv = police;

  	return ret;

  failure_unlock:
  	spin_unlock_bh(&police->tcf_lock);

  failure:

  	if (P_tab)
  		qdisc_put_rtab(P_tab);
  	if (R_tab)
  		qdisc_put_rtab(R_tab);

  	if (ret == ACT_P_CREATED)

  		kfree(police);

  	return err;
  }
  
  static int tcf_act_police_cleanup(struct tc_action *a, int bind)
  {

  	struct tcf_police *p = a->priv;

  	int ret = 0;

  	if (p != NULL) {
  		if (bind)
  			p->tcf_bindcnt--;
  
  		p->tcf_refcnt--;
  		if (p->tcf_refcnt <= 0 && !p->tcf_bindcnt) {
  			tcf_police_destroy(p);
  			ret = 1;
  		}
  	}
  	return ret;

  }

  static int tcf_act_police(struct sk_buff *skb, const struct tc_action *a,

  			  struct tcf_result *res)

  {

  	struct tcf_police *police = a->priv;

  	psched_time_t now;

  	long toks;
  	long ptoks = 0;

  	spin_lock(&police->tcf_lock);

  	bstats_update(&police->tcf_bstats, skb);

  	if (police->tcfp_ewma_rate &&
  	    police->tcf_rate_est.bps >= police->tcfp_ewma_rate) {
  		police->tcf_qstats.overlimits++;

  		if (police->tcf_action == TC_ACT_SHOT)
  			police->tcf_qstats.drops++;

  		spin_unlock(&police->tcf_lock);
  		return police->tcf_action;

  	}

  	if (qdisc_pkt_len(skb) <= police->tcfp_mtu) {

  		if (police->tcfp_R_tab == NULL) {
  			spin_unlock(&police->tcf_lock);
  			return police->tcfp_result;

  		}

  		now = psched_get_time();

  		toks = psched_tdiff_bounded(now, police->tcfp_t_c,
  					    police->tcfp_burst);

  		if (police->tcfp_P_tab) {
  			ptoks = toks + police->tcfp_ptoks;
  			if (ptoks > (long)L2T_P(police, police->tcfp_mtu))
  				ptoks = (long)L2T_P(police, police->tcfp_mtu);

  			ptoks -= L2T_P(police, qdisc_pkt_len(skb));

  		}

  		toks += police->tcfp_toks;
  		if (toks > (long)police->tcfp_burst)
  			toks = police->tcfp_burst;

  		toks -= L2T(police, qdisc_pkt_len(skb));

  		if ((toks|ptoks) >= 0) {

  			police->tcfp_t_c = now;
  			police->tcfp_toks = toks;
  			police->tcfp_ptoks = ptoks;
  			spin_unlock(&police->tcf_lock);
  			return police->tcfp_result;

  		}
  	}

  	police->tcf_qstats.overlimits++;

  	if (police->tcf_action == TC_ACT_SHOT)
  		police->tcf_qstats.drops++;

  	spin_unlock(&police->tcf_lock);
  	return police->tcf_action;

  }
  
  static int
  tcf_act_police_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
  {

  	unsigned char *b = skb_tail_pointer(skb);

  	struct tcf_police *police = a->priv;

  	struct tc_police opt = {
  		.index = police->tcf_index,
  		.action = police->tcf_action,
  		.mtu = police->tcfp_mtu,
  		.burst = police->tcfp_burst,
  		.refcnt = police->tcf_refcnt - ref,
  		.bindcnt = police->tcf_bindcnt - bind,
  	};

  	if (police->tcfp_R_tab)
  		opt.rate = police->tcfp_R_tab->rate;

  	if (police->tcfp_P_tab)
  		opt.peakrate = police->tcfp_P_tab->rate;

  	NLA_PUT(skb, TCA_POLICE_TBF, sizeof(opt), &opt);

  	if (police->tcfp_result)

  		NLA_PUT_U32(skb, TCA_POLICE_RESULT, police->tcfp_result);

  	if (police->tcfp_ewma_rate)

  		NLA_PUT_U32(skb, TCA_POLICE_AVRATE, police->tcfp_ewma_rate);

  	return skb->len;

  nla_put_failure:

  	nlmsg_trim(skb, b);

  	return -1;
  }
  
  MODULE_AUTHOR("Alexey Kuznetsov");
  MODULE_DESCRIPTION("Policing actions");
  MODULE_LICENSE("GPL");
  
  static struct tc_action_ops act_police_ops = {
  	.kind		=	"police",

  	.hinfo		=	&police_hash_info,

  	.type		=	TCA_ID_POLICE,
  	.capab		=	TCA_CAP_NONE,
  	.owner		=	THIS_MODULE,
  	.act		=	tcf_act_police,
  	.dump		=	tcf_act_police_dump,
  	.cleanup	=	tcf_act_police_cleanup,

  	.lookup		=	tcf_hash_search,

  	.init		=	tcf_act_police_locate,

  	.walk		=	tcf_act_police_walker

  };
  
  static int __init
  police_init_module(void)
  {
  	return tcf_register_action(&act_police_ops);
  }
  
  static void __exit
  police_cleanup_module(void)
  {
  	tcf_unregister_action(&act_police_ops);
  }
  
  module_init(police_init_module);
  module_exit(police_cleanup_module);