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Commit 6aaf47fa authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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[PATCH] INET : IPV4 UDP lookups converted to a 2 pass algo 



Some people want to have many UDP sockets, binded to a single port but
many different addresses. We currently hash all those sockets into a
single chain.  Processing of incoming packets is very expensive,
because the whole chain must be examined to find the best match.

I chose in this patch to hash UDP sockets with a hash function that
take into account both their port number and address : This has a
drawback because we need two lookups : one with a given address, one
with a wildcard (null) address.

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 65def812

net/ipv4/udp.c

+114 −57
Original line number Diff line number Diff line
@@ -114,14 +114,33 @@ DEFINE_RWLOCK(udp_hash_lock); 


static int udp_port_rover;



static inline int __udp_lib_lport_inuse(__u16 num, struct hlist_head udptable[])

/*

 * Note about this hash function :

 * Typical use is probably daddr = 0, only dport is going to vary hash

 */

static inline unsigned int hash_port_and_addr(__u16 port, __be32 addr)

{

	addr ^= addr >> 16;

	addr ^= addr >> 8;

	return port ^ addr;

}



static inline int __udp_lib_port_inuse(unsigned int hash, int port,

	__be32 daddr, struct hlist_head udptable[])

{

	struct sock *sk;

	struct hlist_node *node;

	struct inet_sock *inet;



	sk_for_each(sk, node, &udptable[num & (UDP_HTABLE_SIZE - 1)])

		if (sk->sk_hash == num)

	sk_for_each(sk, node, &udptable[hash & (UDP_HTABLE_SIZE - 1)]) {

		if (sk->sk_hash != hash)

			continue;

		inet = inet_sk(sk);

		if (inet->num != port)

			continue;

		if (inet->rcv_saddr == daddr)

			return 1;

	}

	return 0;

}
@@ -142,6 +161,7 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum, 
	struct hlist_node *node;

	struct hlist_head *head;

	struct sock *sk2;

	unsigned int hash;

	int    error = 1;



	write_lock_bh(&udp_hash_lock);
@@ -156,7 +176,9 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum, 
		for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {

			int size;



			head = &udptable[result & (UDP_HTABLE_SIZE - 1)];

			hash = hash_port_and_addr(result,

					inet_sk(sk)->rcv_saddr);

			head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];

			if (hlist_empty(head)) {

				if (result > sysctl_local_port_range[1])

					result = sysctl_local_port_range[0] +
@@ -181,7 +203,10 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum, 
				result = sysctl_local_port_range[0]

					+ ((result - sysctl_local_port_range[0]) &

					   (UDP_HTABLE_SIZE - 1));

			if (! __udp_lib_lport_inuse(result, udptable))

			hash = hash_port_and_addr(result,

					inet_sk(sk)->rcv_saddr);

			if (! __udp_lib_port_inuse(hash, result,

				inet_sk(sk)->rcv_saddr, udptable))

				break;

		}

		if (i >= (1 << 16) / UDP_HTABLE_SIZE)
@@ -189,11 +214,13 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum, 
gotit:

		*port_rover = snum = result;

	} else {

		head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];

		hash = hash_port_and_addr(snum, inet_sk(sk)->rcv_saddr);

		head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];



		sk_for_each(sk2, node, head)

			if (sk2->sk_hash == snum                             &&

			if (sk2->sk_hash == hash                             &&

			    sk2 != sk                                        &&

			    inet_sk(sk2)->num == snum	                     &&

			    (!sk2->sk_reuse        || !sk->sk_reuse)         &&

			    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if

			     || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
@@ -201,9 +228,9 @@ gotit: 
				goto fail;

	}

	inet_sk(sk)->num = snum;

	sk->sk_hash = snum;

	sk->sk_hash = hash;

	if (sk_unhashed(sk)) {

		head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];

		head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];

		sk_add_node(sk, head);

		sock_prot_inc_use(sk->sk_prot);

	}
@@ -242,15 +269,24 @@ static struct sock *__udp4_lib_lookup(__be32 saddr, __be16 sport, 
{

	struct sock *sk, *result = NULL;

	struct hlist_node *node;

	unsigned short hnum = ntohs(dport);

	int badness = -1;

	unsigned int hash, hashwild;

	int score, best = -1;



	hash = hash_port_and_addr(ntohs(dport), daddr);

	hashwild = hash_port_and_addr(ntohs(dport), 0);



	read_lock(&udp_hash_lock);

	sk_for_each(sk, node, &udptable[hnum & (UDP_HTABLE_SIZE - 1)]) {



lookup:



	sk_for_each(sk, node, &udptable[hash & (UDP_HTABLE_SIZE - 1)]) {

		struct inet_sock *inet = inet_sk(sk);



		if (sk->sk_hash == hnum && !ipv6_only_sock(sk)) {

			int score = (sk->sk_family == PF_INET ? 1 : 0);

		if (sk->sk_hash != hash || ipv6_only_sock(sk) ||

			inet->num != dport)

			continue;



		score = (sk->sk_family == PF_INET ? 1 : 0);

		if (inet->rcv_saddr) {

			if (inet->rcv_saddr != daddr)

				continue;
@@ -273,32 +309,38 @@ static struct sock *__udp4_lib_lookup(__be32 saddr, __be16 sport, 
		}

		if (score == 9) {

			result = sk;

				break;

			} else if (score > badness) {

			goto found;

		} else if (score > best) {

			result = sk;

				badness = score;

			best = score;

		}

	}



	if (hash != hashwild) {

		hash = hashwild;

		goto lookup;

	}

found:

	if (result)

		sock_hold(result);

	read_unlock(&udp_hash_lock);

	return result;

}



static inline struct sock *udp_v4_mcast_next(struct sock *sk,

					     __be16 loc_port, __be32 loc_addr,

static inline struct sock *udp_v4_mcast_next(

			struct sock *sk,

			unsigned int hnum, __be16 loc_port, __be32 loc_addr,

			__be16 rmt_port, __be32 rmt_addr,

			int dif)

{

	struct hlist_node *node;

	struct sock *s = sk;

	unsigned short hnum = ntohs(loc_port);



	sk_for_each_from(s, node) {

		struct inet_sock *inet = inet_sk(s);



		if (s->sk_hash != hnum					||

		    inet->num != loc_port				||

		    (inet->daddr && inet->daddr != rmt_addr)		||

		    (inet->dport != rmt_port && inet->dport)		||

		    (inet->rcv_saddr && inet->rcv_saddr != loc_addr)	||
@@ -1129,29 +1171,44 @@ static int __udp4_lib_mcast_deliver(struct sk_buff *skb, 
				    __be32 saddr, __be32 daddr,

				    struct hlist_head udptable[])

{

	struct sock *sk;

	struct sock *sk, *skw, *sknext;

	int dif;

	unsigned int hash = hash_port_and_addr(ntohs(uh->dest), daddr);

	unsigned int hashwild = hash_port_and_addr(ntohs(uh->dest), 0);



	read_lock(&udp_hash_lock);

	sk = sk_head(&udptable[ntohs(uh->dest) & (UDP_HTABLE_SIZE - 1)]);

	dif = skb->dev->ifindex;

	sk = udp_v4_mcast_next(sk, uh->dest, daddr, uh->source, saddr, dif);

	if (sk) {

		struct sock *sknext = NULL;



	read_lock(&udp_hash_lock);



	sk = sk_head(&udptable[hash & (UDP_HTABLE_SIZE - 1)]);

	skw = sk_head(&udptable[hashwild & (UDP_HTABLE_SIZE - 1)]);



	sk = udp_v4_mcast_next(sk, hash, uh->dest, daddr, uh->source, saddr, dif);

	if (!sk) {

		hash = hashwild;

		sk = udp_v4_mcast_next(skw, hash, uh->dest, daddr, uh->source,

			saddr, dif);

	}

	if (sk) {

		do {

			struct sk_buff *skb1 = skb;



			sknext = udp_v4_mcast_next(sk_next(sk), uh->dest, daddr,

						   uh->source, saddr, dif);

			sknext = udp_v4_mcast_next(sk_next(sk), hash, uh->dest,

				daddr, uh->source, saddr, dif);

			if (!sknext && hash != hashwild) {

				hash = hashwild;

				sknext = udp_v4_mcast_next(skw, hash, uh->dest,

					daddr, uh->source, saddr, dif);

			}

			if (sknext)

				skb1 = skb_clone(skb, GFP_ATOMIC);



			if (skb1) {

				int ret = udp_queue_rcv_skb(sk, skb1);

				if (ret > 0)

					/* we should probably re-process instead

					 * of dropping packets here. */

					/*

					 * we should probably re-process

					 * instead of dropping packets here.

					 */

					kfree_skb(skb1);

			}

			sk = sknext;