inetpeer.h

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/*
 *      INETPEER - A storage for permanent information about peers
 *
 *  Authors:    Andrey V. Savochkin <[email protected]>
 */

#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;
    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
     * 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 */
        };
        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;
    u32         flush_seq;
    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) ||
        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 *);
extern void inetpeer_invalidate_family(int family);

/*
 * 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 */