Commit 4b32b5ad authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

ipv6: Stop rt6_info from using inet_peer's metrics 



inet_peer is indexed by the dst address alone.  However, the fib6 tree
could have multiple routing entries (rt6_info) for the same dst. For
example,
1. A /128 dst via multiple gateways.
2. A RTF_CACHE route cloned from a /128 route.

In the above cases, all of them will share the same metrics and
step on each other.

This patch will steer away from inet_peer's metrics and use
dst_cow_metrics_generic() for everything.

Change Highlights:
1. Remove rt6_cow_metrics() which currently acquires metrics from
   inet_peer for DST_HOST route (i.e. /128 route).
2. Add rt6i_pmtu to take care of the pmtu update to avoid creating a
   full size metrics just to override the RTAX_MTU.
3. After (2), the RTF_CACHE route can also share the metrics with its
   dst.from route, by:
   dst_init_metrics(&cache_rt->dst, dst_metrics_ptr(cache_rt->dst.from), true);
4. Stop creating RTF_CACHE route by cloning another RTF_CACHE route.  Instead,
   directly clone from rt->dst.

   [ Currently, cloning from another RTF_CACHE is only possible during
     rt6_do_redirect().  Also, the old clone is removed from the tree
     immediately after the new clone is added. ]

   In case of cloning from an older redirect RTF_CACHE, it should work as
   before.

   In case of cloning from an older pmtu RTF_CACHE, this patch will forget
   the pmtu and re-learn it (if there is any) from the redirected route.

The _rt6i_peer and DST_METRICS_FORCE_OVERWRITE will be removed
in the next cleanup patch.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Reviewed-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 653437d0

include/net/ip6_fib.h

+1 −9
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ struct rt6_info { 
	unsigned long			_rt6i_peer;



	u32				rt6i_metric;

	u32				rt6i_pmtu;

	/* more non-fragment space at head required */

	unsigned short			rt6i_nfheader_len;

	u8				rt6i_protocol;
@@ -189,15 +190,6 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout) 
	rt0->rt6i_flags |= RTF_EXPIRES;

}



static inline void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)

{

	struct dst_entry *new = (struct dst_entry *) from;



	rt->rt6i_flags &= ~RTF_EXPIRES;

	dst_hold(new);

	rt->dst.from = new;

}



static inline void ip6_rt_put(struct rt6_info *rt)

{

	/* dst_release() accepts a NULL parameter.

net/ipv6/route.c

+59 −43
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, 
					   struct sk_buff *skb, u32 mtu);

static void		rt6_do_redirect(struct dst_entry *dst, struct sock *sk,

					struct sk_buff *skb);

static void		rt6_dst_from_metrics_check(struct rt6_info *rt);

static int rt6_score_route(struct rt6_info *rt, int oif, int strict);



#ifdef CONFIG_IPV6_ROUTE_INFO
@@ -137,32 +138,11 @@ static struct inet_peer *rt6_get_peer_create(struct rt6_info *rt) 
static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)

{

	struct rt6_info *rt = (struct rt6_info *)dst;

	struct inet_peer *peer;

	u32 *p = NULL;



	if (!(rt->dst.flags & DST_HOST))

	if (rt->rt6i_flags & RTF_CACHE)

		return NULL;

	else

		return dst_cow_metrics_generic(dst, old);



	peer = rt6_get_peer_create(rt);

	if (peer) {

		u32 *old_p = __DST_METRICS_PTR(old);

		unsigned long prev, new;



		p = peer->metrics;

		if (inet_metrics_new(peer) ||

		    (old & DST_METRICS_FORCE_OVERWRITE))

			memcpy(p, old_p, sizeof(u32) * RTAX_MAX);



		new = (unsigned long) p;

		prev = cmpxchg(&dst->_metrics, old, new);



		if (prev != old) {

			p = __DST_METRICS_PTR(prev);

			if (prev & DST_METRICS_READ_ONLY)

				p = NULL;

		}

	}

	return p;

}



static inline const void *choose_neigh_daddr(struct rt6_info *rt,
@@ -323,7 +303,6 @@ static void ip6_dst_destroy(struct dst_entry *dst) 
	struct inet6_dev *idev = rt->rt6i_idev;

	struct dst_entry *from = dst->from;



	if (!(rt->dst.flags & DST_HOST))

	dst_destroy_metrics_generic(dst);



	if (idev) {
@@ -333,11 +312,6 @@ static void ip6_dst_destroy(struct dst_entry *dst) 


	dst->from = NULL;

	dst_release(from);



	if (rt6_has_peer(rt)) {

		struct inet_peer *peer = rt6_peer_ptr(rt);

		inet_putpeer(peer);

	}

}



static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
@@ -1003,6 +977,7 @@ redo_rt6_select: 
	goto redo_fib6_lookup_lock;



out2:

	rt6_dst_from_metrics_check(rt);

	rt->dst.lastuse = jiffies;

	rt->dst.__use++;
@@ -1111,6 +1086,13 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori 
 *	Destination cache support functions

 */



static void rt6_dst_from_metrics_check(struct rt6_info *rt)

{

	if (rt->dst.from &&

	    dst_metrics_ptr(&rt->dst) != dst_metrics_ptr(rt->dst.from))

		dst_init_metrics(&rt->dst, dst_metrics_ptr(rt->dst.from), true);

}



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

{

	struct rt6_info *rt;
@@ -1127,6 +1109,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie) 
	if (rt6_check_expired(rt))

		return NULL;



	rt6_dst_from_metrics_check(rt);



	return dst;

}
@@ -1179,7 +1163,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, 
		if (mtu < IPV6_MIN_MTU)

			mtu = IPV6_MIN_MTU;



		dst_metric_set(dst, RTAX_MTU, mtu);

		rt6->rt6i_pmtu = mtu;

		rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires);

	}

}
@@ -1359,9 +1343,14 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst) 


static unsigned int ip6_mtu(const struct dst_entry *dst)

{

	const struct rt6_info *rt = (const struct rt6_info *)dst;

	unsigned int mtu = rt->rt6i_pmtu;

	struct inet6_dev *idev;

	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);



	if (mtu)

		goto out;



	mtu = dst_metric_raw(dst, RTAX_MTU);

	if (mtu)

		goto out;
@@ -1947,11 +1936,26 @@ out: 
 *	Misc support functions

 */



static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)

{

	BUG_ON(from->dst.from);



	rt->rt6i_flags &= ~RTF_EXPIRES;

	dst_hold(&from->dst);

	rt->dst.from = &from->dst;

	dst_init_metrics(&rt->dst, dst_metrics_ptr(&from->dst), true);

}



static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,

				    const struct in6_addr *dest)

{

	struct net *net = dev_net(ort->dst.dev);

	struct rt6_info *rt = ip6_dst_alloc(net, ort->dst.dev, 0,

	struct rt6_info *rt;



	if (ort->rt6i_flags & RTF_CACHE)

		ort = (struct rt6_info *)ort->dst.from;



	rt = ip6_dst_alloc(net, ort->dst.dev, 0,

			   ort->rt6i_table);



	if (rt) {
@@ -1961,7 +1965,6 @@ static struct rt6_info *ip6_rt_copy(struct rt6_info *ort, 


		rt->rt6i_dst.addr = *dest;

		rt->rt6i_dst.plen = 128;

		dst_copy_metrics(&rt->dst, &ort->dst);

		rt->dst.error = ort->dst.error;

		rt->rt6i_idev = ort->rt6i_idev;

		if (rt->rt6i_idev)
@@ -2393,12 +2396,21 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg) 
	   PMTU discouvery.

	 */

	if (rt->dst.dev == arg->dev &&

	    !dst_metric_locked(&rt->dst, RTAX_MTU) &&

	    (dst_mtu(&rt->dst) >= arg->mtu ||

	    !dst_metric_locked(&rt->dst, RTAX_MTU)) {

		if (rt->rt6i_flags & RTF_CACHE) {

			/* For RTF_CACHE with rt6i_pmtu == 0

			 * (i.e. a redirected route),

			 * the metrics of its rt->dst.from has already

			 * been updated.

			 */

			if (rt->rt6i_pmtu && rt->rt6i_pmtu > arg->mtu)

				rt->rt6i_pmtu = arg->mtu;

		} else if (dst_mtu(&rt->dst) >= arg->mtu ||

			   (dst_mtu(&rt->dst) < arg->mtu &&

	      dst_mtu(&rt->dst) == idev->cnf.mtu6))) {

			    dst_mtu(&rt->dst) == idev->cnf.mtu6)) {

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

		}

	}

	return 0;

}
@@ -2627,6 +2639,7 @@ static int rt6_fill_node(struct net *net, 
			 int iif, int type, u32 portid, u32 seq,

			 int prefix, int nowait, unsigned int flags)

{

	u32 metrics[RTAX_MAX];

	struct rtmsg *rtm;

	struct nlmsghdr *nlh;

	long expires;
@@ -2740,7 +2753,10 @@ static int rt6_fill_node(struct net *net, 
			goto nla_put_failure;

	}



	if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)

	memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));

	if (rt->rt6i_pmtu)

		metrics[RTAX_MTU - 1] = rt->rt6i_pmtu;

	if (rtnetlink_put_metrics(skb, metrics) < 0)

		goto nla_put_failure;



	if (rt->rt6i_flags & RTF_GATEWAY) {

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