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Commit 30fff923 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

udp: bind() optimisation 



UDP bind() can be O(N^2) in some pathological cases.

Thanks to secondary hash tables, we can make it O(N)

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0ab365f4

include/linux/udp.h

+6 −0
Original line number Diff line number Diff line
@@ -88,6 +88,12 @@ static inline struct udp_sock *udp_sk(const struct sock *sk) 
	return (struct udp_sock *)sk;

}



#define udp_portaddr_for_each_entry(__sk, node, list) \

	hlist_nulls_for_each_entry(__sk, node, list, __sk_common.skc_portaddr_node)



#define udp_portaddr_for_each_entry_rcu(__sk, node, list) \

	hlist_nulls_for_each_entry_rcu(__sk, node, list, __sk_common.skc_portaddr_node)



#define IS_UDPLITE(__sk) (udp_sk(__sk)->pcflag)



#endif

include/net/udp.h

+2 −1
Original line number Diff line number Diff line
@@ -158,7 +158,8 @@ static inline void udp_lib_close(struct sock *sk, long timeout) 
}



extern int	udp_lib_get_port(struct sock *sk, unsigned short snum,

		int (*)(const struct sock*,const struct sock*));

		int (*)(const struct sock *,const struct sock *),

		unsigned int hash2_nulladdr);



/* net/ipv4/udp.c */

extern int	udp_get_port(struct sock *sk, unsigned short snum,

net/ipv4/udp.c

+65 −8
Original line number Diff line number Diff line
@@ -152,16 +152,49 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num, 
	return 0;

}



/*

 * Note: we still hold spinlock of primary hash chain, so no other writer

 * can insert/delete a socket with local_port == num

 */

static int udp_lib_lport_inuse2(struct net *net, __u16 num,

			       struct udp_hslot *hslot2,

			       struct sock *sk,

			       int (*saddr_comp)(const struct sock *sk1,

						 const struct sock *sk2))

{

	struct sock *sk2;

	struct hlist_nulls_node *node;

	int res = 0;



	spin_lock(&hslot2->lock);

	udp_portaddr_for_each_entry(sk2, node, &hslot2->head)

		if (net_eq(sock_net(sk2), net)			&&

		    sk2 != sk					&&

		    (udp_sk(sk2)->udp_port_hash == num)		&&

		    (!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) &&

		    (*saddr_comp)(sk, sk2)) {

			res = 1;

			break;

		}

	spin_unlock(&hslot2->lock);

	return res;

}



/**

 *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6

 *

 *  @sk:          socket struct in question

 *  @snum:        port number to look up

 *  @saddr_comp:  AF-dependent comparison of bound local IP addresses

 *  @hash2_nulladdr: AF-dependant hash value in secondary hash chains,

 *                   with NULL address

 */

int udp_lib_get_port(struct sock *sk, unsigned short snum,

		       int (*saddr_comp)(const struct sock *sk1,

					 const struct sock *sk2))

					 const struct sock *sk2),

		     unsigned int hash2_nulladdr)

{

	struct udp_hslot *hslot, *hslot2;

	struct udp_table *udptable = sk->sk_prot->h.udp_table;
@@ -210,6 +243,30 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, 
	} else {

		hslot = udp_hashslot(udptable, net, snum);

		spin_lock_bh(&hslot->lock);

		if (hslot->count > 10) {

			int exist;

			unsigned int slot2 = udp_sk(sk)->udp_portaddr_hash ^ snum;



			slot2          &= udptable->mask;

			hash2_nulladdr &= udptable->mask;



			hslot2 = udp_hashslot2(udptable, slot2);

			if (hslot->count < hslot2->count)

				goto scan_primary_hash;



			exist = udp_lib_lport_inuse2(net, snum, hslot2,

						     sk, saddr_comp);

			if (!exist && (hash2_nulladdr != slot2)) {

				hslot2 = udp_hashslot2(udptable, hash2_nulladdr);

				exist = udp_lib_lport_inuse2(net, snum, hslot2,

							     sk, saddr_comp);

			}

			if (exist)

				goto fail_unlock;

			else

				goto found;

		}

scan_primary_hash:

		if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk,

					saddr_comp, 0))

			goto fail_unlock;
@@ -255,12 +312,14 @@ static unsigned int udp4_portaddr_hash(struct net *net, __be32 saddr, 


int udp_v4_get_port(struct sock *sk, unsigned short snum)

{

	unsigned int hash2_nulladdr =

		udp4_portaddr_hash(sock_net(sk), INADDR_ANY, snum);

	unsigned int hash2_partial =

		udp4_portaddr_hash(sock_net(sk), inet_sk(sk)->inet_rcv_saddr, 0);



	/* precompute partial secondary hash */

	udp_sk(sk)->udp_portaddr_hash =

		udp4_portaddr_hash(sock_net(sk),

				   inet_sk(sk)->inet_rcv_saddr,

				   0);

	return udp_lib_get_port(sk, snum, ipv4_rcv_saddr_equal);

	udp_sk(sk)->udp_portaddr_hash = hash2_partial;

	return udp_lib_get_port(sk, snum, ipv4_rcv_saddr_equal, hash2_nulladdr);

}



static inline int compute_score(struct sock *sk, struct net *net, __be32 saddr,
@@ -336,8 +395,6 @@ static inline int compute_score2(struct sock *sk, struct net *net, 
	return score;

}



#define udp_portaddr_for_each_entry_rcu(__sk, node, list) \

	hlist_nulls_for_each_entry_rcu(__sk, node, list, __sk_common.skc_portaddr_node)



/* called with read_rcu_lock() */

static struct sock *udp4_lib_lookup2(struct net *net,

net/ipv6/udp.c

+7 −7
Original line number Diff line number Diff line
@@ -100,12 +100,14 @@ static unsigned int udp6_portaddr_hash(struct net *net, 


int udp_v6_get_port(struct sock *sk, unsigned short snum)

{

	unsigned int hash2_nulladdr =

		udp6_portaddr_hash(sock_net(sk), &in6addr_any, snum);

	unsigned int hash2_partial = 

		udp6_portaddr_hash(sock_net(sk), &inet6_sk(sk)->rcv_saddr, 0);



	/* precompute partial secondary hash */

	udp_sk(sk)->udp_portaddr_hash =

		udp6_portaddr_hash(sock_net(sk),

				   &inet6_sk(sk)->rcv_saddr,

				   0);

	return udp_lib_get_port(sk, snum, ipv6_rcv_saddr_equal);

	udp_sk(sk)->udp_portaddr_hash = hash2_partial;

	return udp_lib_get_port(sk, snum, ipv6_rcv_saddr_equal, hash2_nulladdr);

}



static inline int compute_score(struct sock *sk, struct net *net,
@@ -181,8 +183,6 @@ static inline int compute_score2(struct sock *sk, struct net *net, 
	return score;

}



#define udp_portaddr_for_each_entry_rcu(__sk, node, list) \

	hlist_nulls_for_each_entry_rcu(__sk, node, list, __sk_common.skc_portaddr_node)



/* called with read_rcu_lock() */

static struct sock *udp6_lib_lookup2(struct net *net,