linux/include/net/inetpeer.h

/*
 *		INETPEER - A storage for permanent information about peers
 *
 *  Authors:	Andrey V. Savochkin <saw@msu.ru>
 */

#ifndef _NET_INETPEER_H
#define _NET_INETPEER_H

#include <linux/types.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/spinlock.h>
#include <linux/rtnetlink.h>
#include <net/ipv6.h>
#include <linux/atomic.h>

struct inetpeer_addr_base {
	union {
		__be32			a4;
		__be32			a6[4];
	};
};

struct inetpeer_addr {
	struct inetpeer_addr_base	addr;
	__u16				family;
};

struct inet_peer {
	/* group together avl_left,avl_right,v4daddr to speedup lookups */
	struct inet_peer __rcu	*avl_left, *avl_right;
	struct inetpeer_addr	daddr;
	__u32			avl_height;

	u32			metrics[RTAX_MAX];
	u32			rate_tokens;	/* rate limiting for ICMP */
	unsigned long		rate_last;
	unsigned long		pmtu_expires;
	u32			pmtu_orig;
	u32			pmtu_learned;
	struct inetpeer_addr_base redirect_learned;
	union {
		struct list_head	gc_list;
		struct rcu_head     gc_rcu;
	};
	/*
	 * Once inet_peer is queued for deletion (refcnt == -1), following fields
	 * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
	 * We can share memory with rcu_head to help keep inet_peer small.
	 */
	union {
		struct {
			atomic_t			rid;		/* Frag reception counter */
			atomic_t			ip_id_count;	/* IP ID for the next packet */
			__u32				tcp_ts;
			__u32				tcp_ts_stamp;
		};
		struct rcu_head         rcu;
		struct inet_peer	*gc_next;
	};

	/* following fields might be frequently dirtied */
	__u32			dtime;	/* the time of last use of not referenced entries */
	atomic_t		refcnt;
};

struct inet_peer_base {
	struct inet_peer __rcu	*root;
	seqlock_t		lock;
	int			total;
};

#define INETPEER_BASE_BIT	0x1UL

static inline struct inet_peer *inetpeer_ptr(unsigned long val)
{
	BUG_ON(val & INETPEER_BASE_BIT);
	return (struct inet_peer *) val;
}

static inline struct inet_peer_base *inetpeer_base_ptr(unsigned long val)
{
	if (!(val & INETPEER_BASE_BIT))
		return NULL;
	val &= ~INETPEER_BASE_BIT;
	return (struct inet_peer_base *) val;
}

static inline bool inetpeer_ptr_is_peer(unsigned long val)
{
	return !(val & INETPEER_BASE_BIT);
}

static inline void __inetpeer_ptr_set_peer(unsigned long *val, struct inet_peer *peer)
{
	/* This implicitly clears INETPEER_BASE_BIT */
	*val = (unsigned long) peer;
}

static inline bool inetpeer_ptr_set_peer(unsigned long *ptr, struct inet_peer *peer)
{
	unsigned long val = (unsigned long) peer;
	unsigned long orig = *ptr;

	if (!(orig & INETPEER_BASE_BIT) || !val ||
	    cmpxchg(ptr, orig, val) != orig)
		return false;
	return true;
}

static inline void inetpeer_init_ptr(unsigned long *ptr, struct inet_peer_base *base)
{
	*ptr = (unsigned long) base | INETPEER_BASE_BIT;
}

static inline void inetpeer_transfer_peer(unsigned long *to, unsigned long *from)
{
	unsigned long val = *from;

	*to = val;
	if (inetpeer_ptr_is_peer(val)) {
		struct inet_peer *peer = inetpeer_ptr(val);
		atomic_inc(&peer->refcnt);
	}
}

extern void inet_peer_base_init(struct inet_peer_base *);

void			inet_initpeers(void) __init;

#define INETPEER_METRICS_NEW	(~(u32) 0)

static inline bool inet_metrics_new(const struct inet_peer *p)
{
	return p->metrics[RTAX_LOCK-1] == INETPEER_METRICS_NEW;
}

/* can be called with or without local BH being disabled */
struct inet_peer *inet_getpeer(struct inet_peer_base *base,
			       const struct inetpeer_addr *daddr,
			       int create);

static inline struct inet_peer *inet_getpeer_v4(struct inet_peer_base *base,
						__be32 v4daddr,
						int create)
{
	struct inetpeer_addr daddr;

	daddr.addr.a4 = v4daddr;
	daddr.family = AF_INET;
	return inet_getpeer(base, &daddr, create);
}

static inline struct inet_peer *inet_getpeer_v6(struct inet_peer_base *base,
						const struct in6_addr *v6daddr,
						int create)
{
	struct inetpeer_addr daddr;

	*(struct in6_addr *)daddr.addr.a6 = *v6daddr;
	daddr.family = AF_INET6;
	return inet_getpeer(base, &daddr, create);
}

/* can be called from BH context or outside */
extern void inet_putpeer(struct inet_peer *p);
extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);

extern void inetpeer_invalidate_tree(struct inet_peer_base *);

/*
 * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
 * tcp_ts_stamp if no refcount is taken on inet_peer
 */
static inline void inet_peer_refcheck(const struct inet_peer *p)
{
	WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
}


/* can be called with or without local BH being disabled */
static inline int inet_getid(struct inet_peer *p, int more)
{
	int old, new;
	more++;
	inet_peer_refcheck(p);
	do {
		old = atomic_read(&p->ip_id_count);
		new = old + more;
		if (!new)
			new = 1;
	} while (atomic_cmpxchg(&p->ip_id_count, old, new) != old);
	return new;
}

#endif /* _NET_INETPEER_H */