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authorEric Dumazet <eric.dumazet@gmail.com>2009-11-09 05:26:33 +0000
committerDavid S. Miller <davem@davemloft.net>2009-11-10 20:54:38 -0800
commit30fff9231fad757c061285e347b33c5149c2c2e4 (patch)
tree79d07aba4b8de4367090442292e412d1ccf961ef /net/ipv4/udp.c
parent0ab365f463b9c5c8b76476a1808dfde1c38f6f19 (diff)
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: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp.c')
-rw-r--r--net/ipv4/udp.c73
1 files changed, 65 insertions, 8 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index d73e9170536b..1eaf57567ebf 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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,