include/net/inetpeer.h

   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 <net/ipv6.h>
  15 #include <asm/atomic.h>
  16
  17 struct inetpeer_addr {
  18         union {
  19                 __be32          a4;
  20                 __be32          a6[4];
  21         };
  22         __u16   family;
  23 };
  24
  25 struct inet_peer {
  26         /* group together avl_left,avl_right,v4daddr to speedup lookups */
  27         struct inet_peer __rcu  *avl_left, *avl_right;
  28         struct inetpeer_addr    daddr;
  29         __u32                   avl_height;
  30         struct list_head        unused;
  31         __u32                   dtime;          /* the time of last use of not
  32                                                  * referenced entries */
  33         atomic_t                refcnt;
  34         /*
  35          * Once inet_peer is queued for deletion (refcnt == -1), following fields
  36          * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
  37          * We can share memory with rcu_head to keep inet_peer small
  38          */
  39         union {
  40                 struct {
  41                         atomic_t        rid;            /* Frag reception counter */
  42                         atomic_t        ip_id_count;    /* IP ID for the next packet */
  43                         __u32           tcp_ts;
  44                         __u32           tcp_ts_stamp;
  45                 };
  46                 struct rcu_head         rcu;
  47         };
  48 };
  49
  50 void                    inet_initpeers(void) __init;
  51
  52 /* can be called with or without local BH being disabled */
  53 struct inet_peer        *inet_getpeer(struct inetpeer_addr *daddr, int create);
  54
  55 static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
  56 {
  57         struct inetpeer_addr daddr;
  58
  59         daddr.a4 = v4daddr;
  60         daddr.family = AF_INET;
  61         return inet_getpeer(&daddr, create);
  62 }
  63
  64 static inline struct inet_peer *inet_getpeer_v6(struct in6_addr *v6daddr, int create)
  65 {
  66         struct inetpeer_addr daddr;
  67
  68         ipv6_addr_copy((struct in6_addr *)daddr.a6, v6daddr);
  69         daddr.family = AF_INET6;
  70         return inet_getpeer(&daddr, create);
  71 }
  72
  73 /* can be called from BH context or outside */
  74 extern void inet_putpeer(struct inet_peer *p);
  75
  76 /*
  77  * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
  78  * tcp_ts_stamp if no refcount is taken on inet_peer
  79  */
  80 static inline void inet_peer_refcheck(const struct inet_peer *p)
  81 {
  82         WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
  83 }
  84
  85
  86 /* can be called with or without local BH being disabled */
  87 static inline __u16     inet_getid(struct inet_peer *p, int more)
  88 {
  89         more++;
  90         inet_peer_refcheck(p);
  91         return atomic_add_return(more, &p->ip_id_count) - more;
  92 }
  93
  94 #endif /* _NET_INETPEER_H */