linux/include/net/dst.h
Stephen Hemminger c1e20f7c8b tcp: RTT metrics scaling
Some of the metrics (RTT, RTTVAR and RTAX_RTO_MIN) are stored in
kernel units (jiffies) and this leaks out through the netlink API to
user space where the units for jiffies are unknown.

This patches changes the kernel to convert to/from milliseconds. This
changes the ABI, but milliseconds seemed like the most natural unit
for these parameters.  Values available via syscall in
/proc/net/rt_cache and netlink will be in milliseconds.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-18 23:02:15 -07:00

304 lines
6.7 KiB
C

/*
* 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/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/rcupdate.h>
#include <linux/jiffies.h>
#include <net/neighbour.h>
#include <asm/processor.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)
/* Each dst_entry has reference count and sits in some parent list(s).
* When it is removed from parent list, it is "freed" (dst_free).
* After this it enters dead state (dst->obsolete > 0) and if its refcnt
* is zero, it can be destroyed immediately, otherwise it is added
* to gc list and garbage collector periodically checks the refcnt.
*/
struct sk_buff;
struct dst_entry
{
struct rcu_head rcu_head;
struct dst_entry *child;
struct net_device *dev;
short error;
short obsolete;
int flags;
#define DST_HOST 1
#define DST_NOXFRM 2
#define DST_NOPOLICY 4
#define DST_NOHASH 8
unsigned long expires;
unsigned short header_len; /* more space at head required */
unsigned short trailer_len; /* space to reserve at tail */
unsigned int rate_tokens;
unsigned long rate_last; /* rate limiting for ICMP */
struct dst_entry *path;
struct neighbour *neighbour;
struct hh_cache *hh;
struct xfrm_state *xfrm;
int (*input)(struct sk_buff*);
int (*output)(struct sk_buff*);
struct dst_ops *ops;
u32 metrics[RTAX_MAX];
#ifdef CONFIG_NET_CLS_ROUTE
__u32 tclassid;
#endif
/*
* __refcnt wants to be on a different cache line from
* input/output/ops or performance tanks badly
*/
atomic_t __refcnt; /* client references */
int __use;
unsigned long lastuse;
union {
struct dst_entry *next;
struct rtable *rt_next;
struct rt6_info *rt6_next;
struct dn_route *dn_next;
};
};
struct dst_ops
{
unsigned short family;
__be16 protocol;
unsigned gc_thresh;
int (*gc)(struct dst_ops *ops);
struct dst_entry * (*check)(struct dst_entry *, __u32 cookie);
void (*destroy)(struct dst_entry *);
void (*ifdown)(struct dst_entry *,
struct net_device *dev, int how);
struct dst_entry * (*negative_advice)(struct dst_entry *);
void (*link_failure)(struct sk_buff *);
void (*update_pmtu)(struct dst_entry *dst, u32 mtu);
int (*local_out)(struct sk_buff *skb);
int entry_size;
atomic_t entries;
struct kmem_cache *kmem_cachep;
struct net *dst_net;
};
#ifdef __KERNEL__
static inline u32
dst_metric(const struct dst_entry *dst, int metric)
{
return dst->metrics[metric-1];
}
static inline u32 dst_mtu(const struct dst_entry *dst)
{
u32 mtu = dst_metric(dst, RTAX_MTU);
/*
* Alexey put it here, so ask him about it :)
*/
barrier();
return mtu;
}
/* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
{
return msecs_to_jiffies(dst_metric(dst, metric));
}
static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
unsigned long rtt)
{
dst->metrics[metric-1] = jiffies_to_msecs(rtt);
}
static inline u32
dst_allfrag(const struct dst_entry *dst)
{
int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
/* Yes, _exactly_. This is paranoia. */
barrier();
return ret;
}
static inline int
dst_metric_locked(struct dst_entry *dst, int metric)
{
return dst_metric(dst, RTAX_LOCK) & (1<<metric);
}
static inline void dst_hold(struct dst_entry * dst)
{
atomic_inc(&dst->__refcnt);
}
static inline void dst_use(struct dst_entry *dst, unsigned long time)
{
dst_hold(dst);
dst->__use++;
dst->lastuse = time;
}
static inline
struct dst_entry * dst_clone(struct dst_entry * dst)
{
if (dst)
atomic_inc(&dst->__refcnt);
return dst;
}
extern void dst_release(struct dst_entry *dst);
/* Children define the path of the packet through the
* Linux networking. Thus, destinations are stackable.
*/
static inline struct dst_entry *dst_pop(struct dst_entry *dst)
{
struct dst_entry *child = dst_clone(dst->child);
dst_release(dst);
return child;
}
extern int dst_discard(struct sk_buff *skb);
extern void * dst_alloc(struct dst_ops * ops);
extern void __dst_free(struct dst_entry * dst);
extern struct dst_entry *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 = dst_destroy(dst);
if (!dst)
return;
}
__dst_free(dst);
}
static inline void dst_rcu_free(struct rcu_head *head)
{
struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
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 || time_before(expires, dst->expires))
dst->expires = expires;
}
/* Output packet to network from transport. */
static inline int dst_output(struct sk_buff *skb)
{
return skb->dst->output(skb);
}
/* Input packet from network to transport. */
static inline int dst_input(struct sk_buff *skb)
{
int err;
for (;;) {
err = skb->dst->input(skb);
if (likely(err == 0))
return err;
/* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
if (unlikely(err != NET_XMIT_BYPASS))
return err;
}
}
static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
{
if (dst->obsolete)
dst = dst->ops->check(dst, cookie);
return dst;
}
extern void dst_init(void);
/* Flags for xfrm_lookup flags argument. */
enum {
XFRM_LOOKUP_WAIT = 1 << 0,
XFRM_LOOKUP_ICMP = 1 << 1,
};
struct flowi;
#ifndef CONFIG_XFRM
static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
struct sock *sk, int flags)
{
return 0;
}
static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
struct sock *sk, int flags)
{
return 0;
}
#else
extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
struct sock *sk, int flags);
extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
struct sock *sk, int flags);
#endif
#endif
#endif /* _NET_DST_H */