/*

   * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>

   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * Development of this code funded by Astaro AG (http://www.astaro.com/)
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/seqlock.h>
  #include <linux/netlink.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables.h>
  
  struct nft_counter {

  	u64		bytes;
  	u64		packets;
  };

  struct nft_counter_percpu {
  	struct nft_counter	counter;
  	struct u64_stats_sync	syncp;
  };
  
  struct nft_counter_percpu_priv {
  	struct nft_counter_percpu __percpu *counter;
  };

  static void nft_counter_eval(const struct nft_expr *expr,

  			     struct nft_regs *regs,

  			     const struct nft_pktinfo *pkt)
  {

  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);
  	struct nft_counter_percpu *this_cpu;
  
  	local_bh_disable();
  	this_cpu = this_cpu_ptr(priv->counter);
  	u64_stats_update_begin(&this_cpu->syncp);
  	this_cpu->counter.bytes += pkt->skb->len;
  	this_cpu->counter.packets++;
  	u64_stats_update_end(&this_cpu->syncp);
  	local_bh_enable();

  }

  static void nft_counter_fetch(const struct nft_counter_percpu __percpu *counter,
  			      struct nft_counter *total)

  {

  	const struct nft_counter_percpu *cpu_stats;

  	u64 bytes, packets;

  	unsigned int seq;

  	int cpu;

  	memset(total, 0, sizeof(*total));

  	for_each_possible_cpu(cpu) {

  		cpu_stats = per_cpu_ptr(counter, cpu);

  		do {
  			seq	= u64_stats_fetch_begin_irq(&cpu_stats->syncp);
  			bytes	= cpu_stats->counter.bytes;
  			packets	= cpu_stats->counter.packets;
  		} while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, seq));

  		total->packets += packets;
  		total->bytes += bytes;

  	}

  }
  
  static int nft_counter_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);
  	struct nft_counter total;
  
  	nft_counter_fetch(priv->counter, &total);

  
  	if (nla_put_be64(skb, NFTA_COUNTER_BYTES, cpu_to_be64(total.bytes)) ||
  	    nla_put_be64(skb, NFTA_COUNTER_PACKETS, cpu_to_be64(total.packets)))

  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -1;
  }
  
  static const struct nla_policy nft_counter_policy[NFTA_COUNTER_MAX + 1] = {
  	[NFTA_COUNTER_PACKETS]	= { .type = NLA_U64 },
  	[NFTA_COUNTER_BYTES]	= { .type = NLA_U64 },
  };
  
  static int nft_counter_init(const struct nft_ctx *ctx,
  			    const struct nft_expr *expr,
  			    const struct nlattr * const tb[])
  {

  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);
  	struct nft_counter_percpu __percpu *cpu_stats;
  	struct nft_counter_percpu *this_cpu;
  
  	cpu_stats = netdev_alloc_pcpu_stats(struct nft_counter_percpu);
  	if (cpu_stats == NULL)

  		return -ENOMEM;

  
  	preempt_disable();
  	this_cpu = this_cpu_ptr(cpu_stats);
  	if (tb[NFTA_COUNTER_PACKETS]) {
  	        this_cpu->counter.packets =
  			be64_to_cpu(nla_get_be64(tb[NFTA_COUNTER_PACKETS]));
  	}
  	if (tb[NFTA_COUNTER_BYTES]) {
  		this_cpu->counter.bytes =
  			be64_to_cpu(nla_get_be64(tb[NFTA_COUNTER_BYTES]));
  	}
  	preempt_enable();
  	priv->counter = cpu_stats;
  	return 0;
  }

  static void nft_counter_destroy(const struct nft_ctx *ctx,
  				const struct nft_expr *expr)
  {
  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);

  	free_percpu(priv->counter);

  }

  static int nft_counter_clone(struct nft_expr *dst, const struct nft_expr *src)
  {
  	struct nft_counter_percpu_priv *priv = nft_expr_priv(src);
  	struct nft_counter_percpu_priv *priv_clone = nft_expr_priv(dst);
  	struct nft_counter_percpu __percpu *cpu_stats;
  	struct nft_counter_percpu *this_cpu;
  	struct nft_counter total;
  
  	nft_counter_fetch(priv->counter, &total);
  
  	cpu_stats = __netdev_alloc_pcpu_stats(struct nft_counter_percpu,
  					      GFP_ATOMIC);
  	if (cpu_stats == NULL)

  		return -ENOMEM;

  
  	preempt_disable();
  	this_cpu = this_cpu_ptr(cpu_stats);
  	this_cpu->counter.packets = total.packets;
  	this_cpu->counter.bytes = total.bytes;
  	preempt_enable();
  
  	priv_clone->counter = cpu_stats;
  	return 0;
  }

  static struct nft_expr_type nft_counter_type;
  static const struct nft_expr_ops nft_counter_ops = {
  	.type		= &nft_counter_type,

  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_counter_percpu_priv)),

  	.eval		= nft_counter_eval,
  	.init		= nft_counter_init,

  	.destroy	= nft_counter_destroy,

  	.dump		= nft_counter_dump,

  	.clone		= nft_counter_clone,

  };

  static struct nft_expr_type nft_counter_type __read_mostly = {
  	.name		= "counter",
  	.ops		= &nft_counter_ops,
  	.policy		= nft_counter_policy,
  	.maxattr	= NFTA_COUNTER_MAX,

  	.flags		= NFT_EXPR_STATEFUL,

  	.owner		= THIS_MODULE,
  };

  static int __init nft_counter_module_init(void)
  {

  	return nft_register_expr(&nft_counter_type);

  }
  
  static void __exit nft_counter_module_exit(void)
  {

  	nft_unregister_expr(&nft_counter_type);

  }
  
  module_init(nft_counter_module_init);
  module_exit(nft_counter_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  MODULE_ALIAS_NFT_EXPR("counter");