dst.h

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/*
 * net/dst.h    Protocol independent destination cache definitions.
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 */

#ifndef _NET_DST_H
#define _NET_DST_H

#include <linux/config.h>
#include <net/neighbour.h>

/*
 * 0 - no debugging messages
 * 1 - rare events and bugs (default)
 * 2 - trace mode.
 */
#define RT_CACHE_DEBUG          0

#define DST_GC_MIN      (HZ/10)
#define DST_GC_INC      (HZ/2)
#define DST_GC_MAX      (120*HZ)

struct sk_buff;

struct dst_entry
{
        struct dst_entry        *next;
        atomic_t                __refcnt;       /* client references    */
        int                     __use;
        struct net_device       *dev;
        int                     obsolete;
        int                     flags;
#define DST_HOST                1
        unsigned long           lastuse;
        unsigned long           expires;

        unsigned                mxlock;
        unsigned                pmtu;
        unsigned                window;
        unsigned                rtt;
        unsigned                rttvar;
        unsigned                ssthresh;
        unsigned                cwnd;
        unsigned                advmss;
        unsigned                reordering;

        unsigned long           rate_last;      /* rate limiting for ICMP */
        unsigned long           rate_tokens;

        int                     error;

        struct neighbour        *neighbour;
        struct hh_cache         *hh;

        int                     (*input)(struct sk_buff*);
        int                     (*output)(struct sk_buff*);

#ifdef CONFIG_NET_CLS_ROUTE
        __u32                   tclassid;
#endif

        struct  dst_ops         *ops;
                
        char                    info[0];
};


struct dst_ops
{
        unsigned short          family;
        unsigned short          protocol;
        unsigned                gc_thresh;

        int                     (*gc)(void);
        struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
        struct dst_entry *      (*reroute)(struct dst_entry *,
                                           struct sk_buff *);
        void                    (*destroy)(struct dst_entry *);
        struct dst_entry *      (*negative_advice)(struct dst_entry *);
        void                    (*link_failure)(struct sk_buff *);
        int                     entry_size;

        atomic_t                entries;
        kmem_cache_t            *kmem_cachep;
};

#ifdef __KERNEL__

static inline void dst_hold(struct dst_entry * dst)
{
        atomic_inc(&dst->__refcnt);
}

static inline
struct dst_entry * dst_clone(struct dst_entry * dst)
{
        if (dst)
                atomic_inc(&dst->__refcnt);
        return dst;
}

static inline
void dst_release(struct dst_entry * dst)
{
        if (dst)
                atomic_dec(&dst->__refcnt);
}

extern void * dst_alloc(struct dst_ops * ops);
extern void __dst_free(struct dst_entry * dst);
extern void dst_destroy(struct dst_entry * dst);

static inline
void dst_free(struct dst_entry * dst)
{
        if (dst->obsolete > 1)
                return;
        if (!atomic_read(&dst->__refcnt)) {
                dst_destroy(dst);
                return;
        }
        __dst_free(dst);
}

static inline void dst_confirm(struct dst_entry *dst)
{
        if (dst)
                neigh_confirm(dst->neighbour);
}

static inline void dst_negative_advice(struct dst_entry **dst_p)
{
        struct dst_entry * dst = *dst_p;
        if (dst && dst->ops->negative_advice)
                *dst_p = dst->ops->negative_advice(dst);
}

static inline void dst_link_failure(struct sk_buff *skb)
{
        struct dst_entry * dst = skb->dst;
        if (dst && dst->ops && dst->ops->link_failure)
                dst->ops->link_failure(skb);
}

static inline void dst_set_expires(struct dst_entry *dst, int timeout)
{
        unsigned long expires = jiffies + timeout;

        if (expires == 0)
                expires = 1;

        if (dst->expires == 0 || (long)(dst->expires - expires) > 0)
                dst->expires = expires;
}

extern void             dst_init(void);

#endif

#endif /* _NET_DST_H */

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