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 <asm/atomic.h>
  15
  16 struct inet_peer {
  17         /* group together avl_left,avl_right,v4daddr to speedup lookups */
  18         struct inet_peer        *avl_left, *avl_right;
  19         __be32                  v4daddr;        /* peer's address */
  20         __u32                   avl_height;
  21         struct list_head        unused;
  22         __u32                   dtime;          /* the time of last use of not
  23                                                  * referenced entries */
  24         atomic_t                refcnt;
  25         /*
  26          * Once inet_peer is queued for deletion (refcnt == -1), following fields
  27          * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
  28          * We can share memory with rcu_head to keep inet_peer small
  29          * (less then 64 bytes)
  30          */
  31         union {
  32                 struct {
  33                         atomic_t        rid;            /* Frag reception counter */
  34                         atomic_t        ip_id_count;    /* IP ID for the next packet */
  35                         __u32           tcp_ts;
  36                         __u32           tcp_ts_stamp;
  37                 };
  38                 struct rcu_head         rcu;
  39         };
  40 };
  41
  42 void                    inet_initpeers(void) __init;
  43
  44 /* can be called with or without local BH being disabled */
  45 struct inet_peer        *inet_getpeer(__be32 daddr, int create);
  46
  47 /* can be called from BH context or outside */
  48 extern void inet_putpeer(struct inet_peer *p);
  49
  50 /*
  51  * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
  52  * tcp_ts_stamp if no refcount is taken on inet_peer
  53  */
  54 static inline void inet_peer_refcheck(const struct inet_peer *p)
  55 {
  56         WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
  57 }
  58
  59
  60 /* can be called with or without local BH being disabled */
  61 static inline __u16     inet_getid(struct inet_peer *p, int more)
  62 {
  63         more++;
  64         inet_peer_refcheck(p);
  65         return atomic_add_return(more, &p->ip_id_count) - more;
  66 }
  67
  68 #endif /* _NET_INETPEER_H */