Commit d33e4553 authored by David S. Miller's avatar David S. Miller
Browse files

net: Abstract default MTU metric calculation behind an accessor. 



Like RTAX_ADVMSS, make the default calculation go through a dst_ops
method rather than caching the computation in the routing cache
entries.

Now dst metrics are pretty much left as-is when new entries are
created, thus optimizing metric sharing becomes a real possibility.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9fe146ae

include/net/dst.h

+8 −7
Original line number Diff line number Diff line
@@ -113,7 +113,8 @@ static inline u32 
dst_metric(const struct dst_entry *dst, const int metric)

{

	WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||

		     metric == RTAX_ADVMSS);

		     metric == RTAX_ADVMSS ||

		     metric == RTAX_MTU);

	return dst_metric_raw(dst, metric);

}
@@ -156,11 +157,11 @@ dst_feature(const struct dst_entry *dst, u32 feature) 


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();

	u32 mtu = dst_metric_raw(dst, RTAX_MTU);



	if (!mtu)

		mtu = dst->ops->default_mtu(dst);



	return mtu;

}
@@ -186,7 +187,7 @@ dst_allfrag(const struct dst_entry *dst) 
}



static inline int

dst_metric_locked(struct dst_entry *dst, int metric)

dst_metric_locked(const struct dst_entry *dst, int metric)

{

	return dst_metric(dst, RTAX_LOCK) & (1<<metric);

}

include/net/dst_ops.h

+1 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ struct dst_ops { 
	int			(*gc)(struct dst_ops *ops);

	struct dst_entry *	(*check)(struct dst_entry *, __u32 cookie);

	unsigned int		(*default_advmss)(const struct dst_entry *);

	unsigned int		(*default_mtu)(const struct dst_entry *);

	void			(*destroy)(struct dst_entry *);

	void			(*ifdown)(struct dst_entry *,

					  struct net_device *dev, int how);

net/decnet/dn_route.c

+8 −2
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ static unsigned long dn_rt_deadline; 
static int dn_dst_gc(struct dst_ops *ops);

static struct dst_entry *dn_dst_check(struct dst_entry *, __u32);

static unsigned int dn_dst_default_advmss(const struct dst_entry *dst);

static unsigned int dn_dst_default_mtu(const struct dst_entry *dst);

static struct dst_entry *dn_dst_negative_advice(struct dst_entry *);

static void dn_dst_link_failure(struct sk_buff *);

static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu);
@@ -131,6 +132,7 @@ static struct dst_ops dn_dst_ops = { 
	.gc =			dn_dst_gc,

	.check =		dn_dst_check,

	.default_advmss =	dn_dst_default_advmss,

	.default_mtu =		dn_dst_default_mtu,

	.negative_advice =	dn_dst_negative_advice,

	.link_failure =		dn_dst_link_failure,

	.update_pmtu =		dn_dst_update_pmtu,
@@ -803,6 +805,11 @@ static unsigned int dn_dst_default_advmss(const struct dst_entry *dst) 
	return dn_mss_from_pmtu(dst->dev, dst_mtu(dst));

}



static unsigned int dn_dst_default_mtu(const struct dst_entry *dst)

{

	return dst->dev->mtu;

}



static int dn_rt_set_next_hop(struct dn_route *rt, struct dn_fib_res *res)

{

	struct dn_fib_info *fi = res->fi;
@@ -825,8 +832,7 @@ static int dn_rt_set_next_hop(struct dn_route *rt, struct dn_fib_res *res) 
		rt->dst.neighbour = n;

	}



	if (dst_metric(&rt->dst, RTAX_MTU) == 0 ||

	    dst_metric(&rt->dst, RTAX_MTU) > rt->dst.dev->mtu)

	if (dst_metric(&rt->dst, RTAX_MTU) > rt->dst.dev->mtu)

		dst_metric_set(&rt->dst, RTAX_MTU, rt->dst.dev->mtu);

	metric = dst_metric_raw(&rt->dst, RTAX_ADVMSS);

	if (metric) {

net/ipv4/route.c

+20 −9
Original line number Diff line number Diff line
@@ -140,6 +140,7 @@ static unsigned long expires_ljiffies; 


static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);

static unsigned int	 ipv4_default_advmss(const struct dst_entry *dst);

static unsigned int	 ipv4_default_mtu(const struct dst_entry *dst);

static void		 ipv4_dst_destroy(struct dst_entry *dst);

static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);

static void		 ipv4_link_failure(struct sk_buff *skb);
@@ -157,6 +158,7 @@ static struct dst_ops ipv4_dst_ops = { 
	.gc =			rt_garbage_collect,

	.check =		ipv4_dst_check,

	.default_advmss =	ipv4_default_advmss,

	.default_mtu =		ipv4_default_mtu,

	.destroy =		ipv4_dst_destroy,

	.ifdown =		ipv4_dst_ifdown,

	.negative_advice =	ipv4_negative_advice,
@@ -1812,6 +1814,23 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst) 
	return advmss;

}



static unsigned int ipv4_default_mtu(const struct dst_entry *dst)

{

	unsigned int mtu = dst->dev->mtu;



	if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {

		const struct rtable *rt = (const struct rtable *) dst;



		if (rt->rt_gateway != rt->rt_dst && mtu > 576)

			mtu = 576;

	}



	if (mtu > IP_MAX_MTU)

		mtu = IP_MAX_MTU;



	return mtu;

}



static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)

{

	struct dst_entry *dst = &rt->dst;
@@ -1822,18 +1841,10 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag) 
		    FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK)

			rt->rt_gateway = FIB_RES_GW(*res);

		dst_import_metrics(dst, fi->fib_metrics);

		if (fi->fib_mtu == 0) {

			dst_metric_set(dst, RTAX_MTU, dst->dev->mtu);

			if (dst_metric_locked(dst, RTAX_MTU) &&

			    rt->rt_gateway != rt->rt_dst &&

			    dst->dev->mtu > 576)

				dst_metric_set(dst, RTAX_MTU, 576);

		}

#ifdef CONFIG_NET_CLS_ROUTE

		dst->tclassid = FIB_RES_NH(*res).nh_tclassid;

#endif

	} else

		dst_metric_set(dst, RTAX_MTU, dst->dev->mtu);

	}



	if (dst_mtu(dst) > IP_MAX_MTU)

		dst_metric_set(dst, RTAX_MTU, IP_MAX_MTU);

net/ipv6/route.c

+16 −21
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ 
static struct rt6_info * ip6_rt_copy(struct rt6_info *ort);

static struct dst_entry	*ip6_dst_check(struct dst_entry *dst, u32 cookie);

static unsigned int	 ip6_default_advmss(const struct dst_entry *dst);

static unsigned int	 ip6_default_mtu(const struct dst_entry *dst);

static struct dst_entry *ip6_negative_advice(struct dst_entry *);

static void		ip6_dst_destroy(struct dst_entry *);

static void		ip6_dst_ifdown(struct dst_entry *,
@@ -105,6 +106,7 @@ static struct dst_ops ip6_dst_ops_template = { 
	.gc_thresh		=	1024,

	.check			=	ip6_dst_check,

	.default_advmss		=	ip6_default_advmss,

	.default_mtu		=	ip6_default_mtu,

	.destroy		=	ip6_dst_destroy,

	.ifdown			=	ip6_dst_ifdown,

	.negative_advice	=	ip6_negative_advice,
@@ -937,8 +939,6 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, u32 mtu) 
	}

}



static int ipv6_get_mtu(struct net_device *dev);



static unsigned int ip6_default_advmss(const struct dst_entry *dst)

{

	struct net_device *dev = dst->dev;
@@ -961,6 +961,20 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst) 
	return mtu;

}



static unsigned int ip6_default_mtu(const struct dst_entry *dst)

{

	unsigned int mtu = IPV6_MIN_MTU;

	struct inet6_dev *idev;



	rcu_read_lock();

	idev = __in6_dev_get(dst->dev);

	if (idev)

		mtu = idev->cnf.mtu6;

	rcu_read_unlock();



	return mtu;

}



static struct dst_entry *icmp6_dst_gc_list;

static DEFINE_SPINLOCK(icmp6_dst_lock);
@@ -995,7 +1009,6 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev, 
	rt->rt6i_nexthop  = neigh;

	atomic_set(&rt->dst.__refcnt, 1);

	dst_metric_set(&rt->dst, RTAX_HOPLIMIT, 255);

	dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(rt->rt6i_dev));

	rt->dst.output  = ip6_output;



#if 0	/* there's no chance to use these for ndisc */
@@ -1094,19 +1107,6 @@ out: 
   Remove it only when all the things will work!

 */



static int ipv6_get_mtu(struct net_device *dev)

{

	int mtu = IPV6_MIN_MTU;

	struct inet6_dev *idev;



	rcu_read_lock();

	idev = __in6_dev_get(dev);

	if (idev)

		mtu = idev->cnf.mtu6;

	rcu_read_unlock();

	return mtu;

}



int ip6_dst_hoplimit(struct dst_entry *dst)

{

	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
@@ -1315,8 +1315,6 @@ install_route: 
		}

	}



	if (!dst_mtu(&rt->dst))

		dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(dev));

	rt->dst.dev = dev;

	rt->rt6i_idev = idev;

	rt->rt6i_table = table;
@@ -1541,8 +1539,6 @@ void rt6_redirect(struct in6_addr *dest, struct in6_addr *src, 


	ipv6_addr_copy(&nrt->rt6i_gateway, (struct in6_addr*)neigh->primary_key);

	nrt->rt6i_nexthop = neigh_clone(neigh);

	/* Reset pmtu, it may be better */

	dst_metric_set(&nrt->dst, RTAX_MTU, ipv6_get_mtu(neigh->dev));



	if (ip6_ins_rt(nrt))

		goto out;
@@ -1971,7 +1967,6 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev, 
	rt->dst.output = ip6_output;

	rt->rt6i_dev = net->loopback_dev;

	rt->rt6i_idev = idev;

	dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(rt->rt6i_dev));

	dst_metric_set(&rt->dst, RTAX_HOPLIMIT, -1);

	rt->dst.obsolete = -1;

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