Commit aee06da6 authored by Julian Anastasov's avatar Julian Anastasov Committed by David S. Miller
Browse files

ipv4: use seqlock for nh_exceptions 



Use global seqlock for the nh_exceptions. Call
fnhe_oldest with the right hash chain. Correct the diff
value for dst_set_expires.

v2: after suggestions from Eric Dumazet:
* get rid of spin lock fnhe_lock, rearrange update_or_create_fnhe
* continue daddr search in rt_bind_exception

v3:
* remove the daddr check before seqlock in rt_bind_exception
* restart lookup in rt_bind_exception on detected seqlock change,
as suggested by David Miller

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7fed84f6

include/net/ip_fib.h

+1 −1
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ struct fib_nh_exception { 
	struct fib_nh_exception __rcu	*fnhe_next;

	__be32				fnhe_daddr;

	u32				fnhe_pmtu;

	u32				fnhe_gw;

	__be32				fnhe_gw;

	unsigned long			fnhe_expires;

	unsigned long			fnhe_stamp;

};

net/ipv4/route.c

+68 −50
Original line number Diff line number Diff line
@@ -1333,9 +1333,9 @@ static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk, 
		build_sk_flow_key(fl4, sk);

}



static DEFINE_SPINLOCK(fnhe_lock);

static DEFINE_SEQLOCK(fnhe_seqlock);



static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash, __be32 daddr)

static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)

{

	struct fib_nh_exception *fnhe, *oldest;
@@ -1358,47 +1358,63 @@ static inline u32 fnhe_hashfun(__be32 daddr) 
	return hval & (FNHE_HASH_SIZE - 1);

}



static struct fib_nh_exception *find_or_create_fnhe(struct fib_nh *nh, __be32 daddr)

static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,

				  u32 pmtu, unsigned long expires)

{

	struct fnhe_hash_bucket *hash = nh->nh_exceptions;

	struct fnhe_hash_bucket *hash;

	struct fib_nh_exception *fnhe;

	int depth;

	u32 hval;

	u32 hval = fnhe_hashfun(daddr);



	write_seqlock_bh(&fnhe_seqlock);



	hash = nh->nh_exceptions;

	if (!hash) {

		hash = nh->nh_exceptions = kzalloc(FNHE_HASH_SIZE * sizeof(*hash),

						   GFP_ATOMIC);

		hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);

		if (!hash)

			return NULL;

			goto out_unlock;

		nh->nh_exceptions = hash;

	}



	hval = fnhe_hashfun(daddr);

	hash += hval;



	depth = 0;

	for (fnhe = rcu_dereference(hash->chain); fnhe;

	     fnhe = rcu_dereference(fnhe->fnhe_next)) {

		if (fnhe->fnhe_daddr == daddr)

			goto out;

			break;

		depth++;

	}



	if (depth > FNHE_RECLAIM_DEPTH) {

		fnhe = fnhe_oldest(hash + hval, daddr);

		goto out_daddr;

	if (fnhe) {

		if (gw)

			fnhe->fnhe_gw = gw;

		if (pmtu) {

			fnhe->fnhe_pmtu = pmtu;

			fnhe->fnhe_expires = expires;

		}

	} else {

		if (depth > FNHE_RECLAIM_DEPTH)

			fnhe = fnhe_oldest(hash);

		else {

			fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);

			if (!fnhe)

		return NULL;

				goto out_unlock;



			fnhe->fnhe_next = hash->chain;

			rcu_assign_pointer(hash->chain, fnhe);



out_daddr:

		}

		fnhe->fnhe_daddr = daddr;

out:

		fnhe->fnhe_gw = gw;

		fnhe->fnhe_pmtu = pmtu;

		fnhe->fnhe_expires = expires;

	}



	fnhe->fnhe_stamp = jiffies;

	return fnhe;



out_unlock:

	write_sequnlock_bh(&fnhe_seqlock);

	return;

}



static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4)
@@ -1452,13 +1468,9 @@ static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flow 
		} else {

			if (fib_lookup(net, fl4, &res) == 0) {

				struct fib_nh *nh = &FIB_RES_NH(res);

				struct fib_nh_exception *fnhe;



				spin_lock_bh(&fnhe_lock);

				fnhe = find_or_create_fnhe(nh, fl4->daddr);

				if (fnhe)

					fnhe->fnhe_gw = new_gw;

				spin_unlock_bh(&fnhe_lock);

				update_or_create_fnhe(nh, fl4->daddr, new_gw,

						      0, 0);

			}

			rt->rt_gateway = new_gw;

			rt->rt_flags |= RTCF_REDIRECTED;
@@ -1663,15 +1675,9 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) 


	if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) {

		struct fib_nh *nh = &FIB_RES_NH(res);

		struct fib_nh_exception *fnhe;



		spin_lock_bh(&fnhe_lock);

		fnhe = find_or_create_fnhe(nh, fl4->daddr);

		if (fnhe) {

			fnhe->fnhe_pmtu = mtu;

			fnhe->fnhe_expires = jiffies + ip_rt_mtu_expires;

		}

		spin_unlock_bh(&fnhe_lock);

		update_or_create_fnhe(nh, fl4->daddr, 0, mtu,

				      jiffies + ip_rt_mtu_expires);

	}

	rt->rt_pmtu = mtu;

	dst_set_expires(&rt->dst, ip_rt_mtu_expires);
@@ -1902,25 +1908,37 @@ static void rt_bind_exception(struct rtable *rt, struct fib_nh *nh, __be32 daddr 


	hval = fnhe_hashfun(daddr);



restart:

	for (fnhe = rcu_dereference(hash[hval].chain); fnhe;

	     fnhe = rcu_dereference(fnhe->fnhe_next)) {

		if (fnhe->fnhe_daddr == daddr) {

			if (fnhe->fnhe_pmtu) {

				unsigned long expires = fnhe->fnhe_expires;

				unsigned long diff = expires - jiffies;

		__be32 fnhe_daddr, gw;

		unsigned long expires;

		unsigned int seq;

		u32 pmtu;



		seq = read_seqbegin(&fnhe_seqlock);

		fnhe_daddr = fnhe->fnhe_daddr;

		gw = fnhe->fnhe_gw;

		pmtu = fnhe->fnhe_pmtu;

		expires = fnhe->fnhe_expires;

		if (read_seqretry(&fnhe_seqlock, seq))

			goto restart;

		if (daddr != fnhe_daddr)

			continue;

		if (pmtu) {

			unsigned long diff = jiffies - expires;



			if (time_before(jiffies, expires)) {

					rt->rt_pmtu = fnhe->fnhe_pmtu;

				rt->rt_pmtu = pmtu;

				dst_set_expires(&rt->dst, diff);

			}

		}

			if (fnhe->fnhe_gw)

				rt->rt_gateway = fnhe->fnhe_gw;

		if (gw)

			rt->rt_gateway = gw;

		fnhe->fnhe_stamp = jiffies;

		break;

	}

}

}



static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,

			   const struct fib_result *res,

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