/*
   * net/sched/cls_cgroup.c	Control Group Classifier
   *
   *		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:	Thomas Graf <tgraf@suug.ch>
   */
  
  #include <linux/module.h>

  #include <linux/slab.h>

  #include <linux/skbuff.h>

  #include <linux/rcupdate.h>

  #include <net/rtnetlink.h>
  #include <net/pkt_cls.h>

  #include <net/sock.h>
  #include <net/cls_cgroup.h>

  struct cls_cgroup_head {

  	u32			handle;
  	struct tcf_exts		exts;
  	struct tcf_ematch_tree	ematches;

  	struct tcf_proto	*tp;

  	union {
  		struct work_struct	work;
  		struct rcu_head		rcu;
  	};

  };

  static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,

  			       struct tcf_result *res)
  {

  	struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);

  	u32 classid = task_get_classid(skb);

  	if (!classid)
  		return -1;

  	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
  		return -1;
  
  	res->classid = classid;
  	res->class = 0;

  	return tcf_exts_exec(skb, &head->exts, res);

  }

  static void *cls_cgroup_get(struct tcf_proto *tp, u32 handle)

  {

  	return NULL;

  }

  static int cls_cgroup_init(struct tcf_proto *tp)
  {
  	return 0;
  }

  static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
  	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
  };

  static void __cls_cgroup_destroy(struct cls_cgroup_head *head)
  {
  	tcf_exts_destroy(&head->exts);
  	tcf_em_tree_destroy(&head->ematches);
  	tcf_exts_put_net(&head->exts);
  	kfree(head);
  }

  static void cls_cgroup_destroy_work(struct work_struct *work)
  {
  	struct cls_cgroup_head *head = container_of(work,
  						    struct cls_cgroup_head,
  						    work);
  	rtnl_lock();

  	__cls_cgroup_destroy(head);

  	rtnl_unlock();
  }

  static void cls_cgroup_destroy_rcu(struct rcu_head *root)
  {
  	struct cls_cgroup_head *head = container_of(root,
  						    struct cls_cgroup_head,
  						    rcu);

  	INIT_WORK(&head->work, cls_cgroup_destroy_work);
  	tcf_queue_work(&head->work);

  }

  static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,

  			     struct tcf_proto *tp, unsigned long base,

  			     u32 handle, struct nlattr **tca,

  			     void **arg, bool ovr)

  {

  	struct nlattr *tb[TCA_CGROUP_MAX + 1];

  	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
  	struct cls_cgroup_head *new;

  	int err;

  	if (!tca[TCA_OPTIONS])
  		return -EINVAL;

  	if (!head && !handle)
  		return -EINVAL;

  	if (head && handle != head->handle)
  		return -ENOENT;

  	new = kzalloc(sizeof(*head), GFP_KERNEL);
  	if (!new)
  		return -ENOBUFS;

  	err = tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
  	if (err < 0)
  		goto errout;

  	new->handle = handle;

  	new->tp = tp;

  	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],

  			       cgroup_policy, NULL);

  	if (err < 0)

  		goto errout;

  	err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &new->exts, ovr);

  	if (err < 0)

  		goto errout;

  	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &new->ematches);

  	if (err < 0)

  		goto errout;

  	rcu_assign_pointer(tp->root, new);

  	if (head) {
  		tcf_exts_get_net(&head->exts);

  		call_rcu(&head->rcu, cls_cgroup_destroy_rcu);

  	}

  	return 0;

  errout:

  	tcf_exts_destroy(&new->exts);

  	kfree(new);
  	return err;

  }

  static void cls_cgroup_destroy(struct tcf_proto *tp)

  {

  	struct cls_cgroup_head *head = rtnl_dereference(tp->root);

  	/* Head can still be NULL due to cls_cgroup_init(). */

  	if (head) {
  		if (tcf_exts_get_net(&head->exts))
  			call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
  		else
  			__cls_cgroup_destroy(head);
  	}

  }

  static int cls_cgroup_delete(struct tcf_proto *tp, void *arg, bool *last)

  {
  	return -EOPNOTSUPP;
  }
  
  static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
  {

  	struct cls_cgroup_head *head = rtnl_dereference(tp->root);

  
  	if (arg->count < arg->skip)
  		goto skip;

  	if (arg->fn(tp, head, arg) < 0) {

  		arg->stop = 1;
  		return;
  	}
  skip:
  	arg->count++;
  }

  static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, void *fh,

  			   struct sk_buff *skb, struct tcmsg *t)
  {

  	struct cls_cgroup_head *head = rtnl_dereference(tp->root);

  	struct nlattr *nest;
  
  	t->tcm_handle = head->handle;
  
  	nest = nla_nest_start(skb, TCA_OPTIONS);
  	if (nest == NULL)
  		goto nla_put_failure;

  	if (tcf_exts_dump(skb, &head->exts) < 0 ||

  	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
  		goto nla_put_failure;
  
  	nla_nest_end(skb, nest);

  	if (tcf_exts_dump_stats(skb, &head->exts) < 0)

  		goto nla_put_failure;
  
  	return skb->len;
  
  nla_put_failure:

  	nla_nest_cancel(skb, nest);

  	return -1;
  }
  
  static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
  	.kind		=	"cgroup",
  	.init		=	cls_cgroup_init,
  	.change		=	cls_cgroup_change,
  	.classify	=	cls_cgroup_classify,
  	.destroy	=	cls_cgroup_destroy,
  	.get		=	cls_cgroup_get,

  	.delete		=	cls_cgroup_delete,
  	.walk		=	cls_cgroup_walk,
  	.dump		=	cls_cgroup_dump,
  	.owner		=	THIS_MODULE,
  };
  
  static int __init init_cgroup_cls(void)
  {

  	return register_tcf_proto_ops(&cls_cgroup_ops);

  }
  
  static void __exit exit_cgroup_cls(void)
  {
  	unregister_tcf_proto_ops(&cls_cgroup_ops);
  }
  
  module_init(init_cgroup_cls);
  module_exit(exit_cgroup_cls);
  MODULE_LICENSE("GPL");