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 <linux/rtnetlink.h>
  15 #include <net/ipv6.h>
  16 #include <asm/atomic.h>
  17
  18 struct inetpeer_addr {
  19         union {
  20                 __be32          a4;
  21                 __be32          a6[4];
  22         };
  23         __u16   family;
  24 };
  25
  26 struct inet_peer {
  27         /* group together avl_left,avl_right,v4daddr to speedup lookups */
  28         struct inet_peer __rcu  *avl_left, *avl_right;
  29         struct inetpeer_addr    daddr;
  30         __u32                   avl_height;
  31         struct list_head        unused;
  32         __u32                   dtime;          /* the time of last use of not
  33                                                  * referenced entries */
  34         atomic_t                refcnt;
  35         /*
  36          * Once inet_peer is queued for deletion (refcnt == -1), following fields
  37          * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp, metrics
  38          * We can share memory with rcu_head to help keep inet_peer small.
  39          */
  40         union {
  41                 struct {
  42                         atomic_t        rid;            /* Frag reception counter */
  43                         atomic_t        ip_id_count;    /* IP ID for the next packet */
  44                         __u32           tcp_ts;
  45                         __u32           tcp_ts_stamp;
  46                         u32             metrics[RTAX_MAX];
  47                 };
  48                 struct rcu_head         rcu;
  49         };
  50 };
  51
  52 void                    inet_initpeers(void) __init;
  53
  54 /* can be called with or without local BH being disabled */
  55 struct inet_peer        *inet_getpeer(struct inetpeer_addr *daddr, int create);
  56
  57 static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
  58 {
  59         struct inetpeer_addr daddr;
  60
  61         daddr.a4 = v4daddr;
  62         daddr.family = AF_INET;
  63         return inet_getpeer(&daddr, create);
  64 }
  65
  66 static inline struct inet_peer *inet_getpeer_v6(struct in6_addr *v6daddr, int create)
  67 {
  68         struct inetpeer_addr daddr;
  69
  70         ipv6_addr_copy((struct in6_addr *)daddr.a6, v6daddr);
  71         daddr.family = AF_INET6;
  72         return inet_getpeer(&daddr, create);
  73 }
  74
  75 /* can be called from BH context or outside */
  76 extern void inet_putpeer(struct inet_peer *p);
  77
  78 /*
  79  * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
  80  * tcp_ts_stamp if no refcount is taken on inet_peer
  81  */
  82 static inline void inet_peer_refcheck(const struct inet_peer *p)
  83 {
  84         WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
  85 }
  86
  87
  88 /* can be called with or without local BH being disabled */
  89 static inline __u16     inet_getid(struct inet_peer *p, int more)
  90 {
  91         more++;
  92         inet_peer_refcheck(p);
  93         return atomic_add_return(more, &p->ip_id_count) - more;
  94 }
  95
  96 #endif /* _NET_INETPEER_H */