linux/include/net/inetpeer.h
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   1/*
   2 *              INETPEER - A storage for permanent information about peers
   3 *
   4 *  Authors:    Andrey V. Savochkin <saw@msu.ru>
   5 */
   6
   7#ifndef _NET_INETPEER_H
   8#define _NET_INETPEER_H
   9
  10#include <linux/types.h>
  11#include <linux/init.h>
  12#include <linux/jiffies.h>
  13#include <linux/spinlock.h>
  14#include <linux/rtnetlink.h>
  15#include <net/ipv6.h>
  16#include <linux/atomic.h>
  17
  18struct inetpeer_addr_base {
  19        union {
  20                __be32                  a4;
  21                __be32                  a6[4];
  22        };
  23};
  24
  25struct inetpeer_addr {
  26        struct inetpeer_addr_base       addr;
  27        __u16                           family;
  28};
  29
  30struct inet_peer {
  31        /* group together avl_left,avl_right,v4daddr to speedup lookups */
  32        struct inet_peer __rcu  *avl_left, *avl_right;
  33        struct inetpeer_addr    daddr;
  34        __u32                   avl_height;
  35
  36        u32                     metrics[RTAX_MAX];
  37        u32                     rate_tokens;    /* rate limiting for ICMP */
  38        unsigned long           rate_last;
  39        union {
  40                struct list_head        gc_list;
  41                struct rcu_head     gc_rcu;
  42        };
  43        /*
  44         * Once inet_peer is queued for deletion (refcnt == -1), following fields
  45         * are not available: rid, ip_id_count
  46         * We can share memory with rcu_head to help keep inet_peer small.
  47         */
  48        union {
  49                struct {
  50                        atomic_t                        rid;            /* Frag reception counter */
  51                        atomic_t                        ip_id_count;    /* IP ID for the next packet */
  52                };
  53                struct rcu_head         rcu;
  54                struct inet_peer        *gc_next;
  55        };
  56
  57        /* following fields might be frequently dirtied */
  58        __u32                   dtime;  /* the time of last use of not referenced entries */
  59        atomic_t                refcnt;
  60};
  61
  62struct inet_peer_base {
  63        struct inet_peer __rcu  *root;
  64        seqlock_t               lock;
  65        u32                     flush_seq;
  66        int                     total;
  67};
  68
  69#define INETPEER_BASE_BIT       0x1UL
  70
  71static inline struct inet_peer *inetpeer_ptr(unsigned long val)
  72{
  73        BUG_ON(val & INETPEER_BASE_BIT);
  74        return (struct inet_peer *) val;
  75}
  76
  77static inline struct inet_peer_base *inetpeer_base_ptr(unsigned long val)
  78{
  79        if (!(val & INETPEER_BASE_BIT))
  80                return NULL;
  81        val &= ~INETPEER_BASE_BIT;
  82        return (struct inet_peer_base *) val;
  83}
  84
  85static inline bool inetpeer_ptr_is_peer(unsigned long val)
  86{
  87        return !(val & INETPEER_BASE_BIT);
  88}
  89
  90static inline void __inetpeer_ptr_set_peer(unsigned long *val, struct inet_peer *peer)
  91{
  92        /* This implicitly clears INETPEER_BASE_BIT */
  93        *val = (unsigned long) peer;
  94}
  95
  96static inline bool inetpeer_ptr_set_peer(unsigned long *ptr, struct inet_peer *peer)
  97{
  98        unsigned long val = (unsigned long) peer;
  99        unsigned long orig = *ptr;
 100
 101        if (!(orig & INETPEER_BASE_BIT) ||
 102            cmpxchg(ptr, orig, val) != orig)
 103                return false;
 104        return true;
 105}
 106
 107static inline void inetpeer_init_ptr(unsigned long *ptr, struct inet_peer_base *base)
 108{
 109        *ptr = (unsigned long) base | INETPEER_BASE_BIT;
 110}
 111
 112static inline void inetpeer_transfer_peer(unsigned long *to, unsigned long *from)
 113{
 114        unsigned long val = *from;
 115
 116        *to = val;
 117        if (inetpeer_ptr_is_peer(val)) {
 118                struct inet_peer *peer = inetpeer_ptr(val);
 119                atomic_inc(&peer->refcnt);
 120        }
 121}
 122
 123extern void inet_peer_base_init(struct inet_peer_base *);
 124
 125void                    inet_initpeers(void) __init;
 126
 127#define INETPEER_METRICS_NEW    (~(u32) 0)
 128
 129static inline bool inet_metrics_new(const struct inet_peer *p)
 130{
 131        return p->metrics[RTAX_LOCK-1] == INETPEER_METRICS_NEW;
 132}
 133
 134/* can be called with or without local BH being disabled */
 135struct inet_peer *inet_getpeer(struct inet_peer_base *base,
 136                               const struct inetpeer_addr *daddr,
 137                               int create);
 138
 139static inline struct inet_peer *inet_getpeer_v4(struct inet_peer_base *base,
 140                                                __be32 v4daddr,
 141                                                int create)
 142{
 143        struct inetpeer_addr daddr;
 144
 145        daddr.addr.a4 = v4daddr;
 146        daddr.family = AF_INET;
 147        return inet_getpeer(base, &daddr, create);
 148}
 149
 150static inline struct inet_peer *inet_getpeer_v6(struct inet_peer_base *base,
 151                                                const struct in6_addr *v6daddr,
 152                                                int create)
 153{
 154        struct inetpeer_addr daddr;
 155
 156        *(struct in6_addr *)daddr.addr.a6 = *v6daddr;
 157        daddr.family = AF_INET6;
 158        return inet_getpeer(base, &daddr, create);
 159}
 160
 161/* can be called from BH context or outside */
 162extern void inet_putpeer(struct inet_peer *p);
 163extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
 164
 165extern void inetpeer_invalidate_tree(struct inet_peer_base *);
 166extern void inetpeer_invalidate_family(int family);
 167
 168/*
 169 * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
 170 * tcp_ts_stamp if no refcount is taken on inet_peer
 171 */
 172static inline void inet_peer_refcheck(const struct inet_peer *p)
 173{
 174        WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
 175}
 176
 177
 178/* can be called with or without local BH being disabled */
 179static inline int inet_getid(struct inet_peer *p, int more)
 180{
 181        int old, new;
 182        more++;
 183        inet_peer_refcheck(p);
 184        do {
 185                old = atomic_read(&p->ip_id_count);
 186                new = old + more;
 187                if (!new)
 188                        new = 1;
 189        } while (atomic_cmpxchg(&p->ip_id_count, old, new) != old);
 190        return new;
 191}
 192
 193#endif /* _NET_INETPEER_H */
 194
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