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Commit 2cb4bbd7 authored by Liping Zhang's avatar Liping Zhang Committed by Pablo Neira Ayuso
Browse files

netfilter: limit: use per-rule spinlock to improve the scalability 



The limit token is independent between each rules, so there's no
need to use a global spinlock.

Signed-off-by: default avatarLiping Zhang <zlpnobody@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent fc09e4a7

net/netfilter/nft_limit.c

+5 −5
Original line number Diff line number Diff line
@@ -17,9 +17,8 @@ 
#include <linux/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables.h>



static DEFINE_SPINLOCK(limit_lock);



struct nft_limit {

	spinlock_t	lock;

	u64		last;

	u64		tokens;

	u64		tokens_max;
@@ -34,7 +33,7 @@ static inline bool nft_limit_eval(struct nft_limit *limit, u64 cost) 
	u64 now, tokens;

	s64 delta;



	spin_lock_bh(&limit_lock);

	spin_lock_bh(&limit->lock);

	now = ktime_get_ns();

	tokens = limit->tokens + now - limit->last;

	if (tokens > limit->tokens_max)
@@ -44,11 +43,11 @@ static inline bool nft_limit_eval(struct nft_limit *limit, u64 cost) 
	delta = tokens - cost;

	if (delta >= 0) {

		limit->tokens = delta;

		spin_unlock_bh(&limit_lock);

		spin_unlock_bh(&limit->lock);

		return limit->invert;

	}

	limit->tokens = tokens;

	spin_unlock_bh(&limit_lock);

	spin_unlock_bh(&limit->lock);

	return !limit->invert;

}
@@ -86,6 +85,7 @@ static int nft_limit_init(struct nft_limit *limit, 
			limit->invert = true;

	}

	limit->last = ktime_get_ns();

	spin_lock_init(&limit->lock);



	return 0;

}

net/netfilter/xt_limit.c

+6 −5
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/netfilter/xt_limit.h>



struct xt_limit_priv {

	spinlock_t lock;

	unsigned long prev;

	uint32_t credit;

};
@@ -32,8 +33,6 @@ MODULE_ALIAS("ip6t_limit"); 
 * see net/sched/sch_tbf.c in the linux source tree

 */



static DEFINE_SPINLOCK(limit_lock);



/* Rusty: This is my (non-mathematically-inclined) understanding of

   this algorithm.  The `average rate' in jiffies becomes your initial

   amount of credit `credit' and the most credit you can ever have
@@ -72,7 +71,7 @@ limit_mt(const struct sk_buff *skb, struct xt_action_param *par) 
	struct xt_limit_priv *priv = r->master;

	unsigned long now = jiffies;



	spin_lock_bh(&limit_lock);

	spin_lock_bh(&priv->lock);

	priv->credit += (now - xchg(&priv->prev, now)) * CREDITS_PER_JIFFY;

	if (priv->credit > r->credit_cap)

		priv->credit = r->credit_cap;
@@ -80,11 +79,11 @@ limit_mt(const struct sk_buff *skb, struct xt_action_param *par) 
	if (priv->credit >= r->cost) {

		/* We're not limited. */

		priv->credit -= r->cost;

		spin_unlock_bh(&limit_lock);

		spin_unlock_bh(&priv->lock);

		return true;

	}



	spin_unlock_bh(&limit_lock);

	spin_unlock_bh(&priv->lock);

	return false;

}
@@ -126,6 +125,8 @@ static int limit_mt_check(const struct xt_mtchk_param *par) 
		r->credit_cap = priv->credit; /* Credits full. */

		r->cost = user2credits(r->avg);

	}

	spin_lock_init(&priv->lock);



	return 0;

}