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[PATCH] INET : IPV4 UDP lookups converted to a 2 pass algo
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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: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed Apr 30, 2007
1 parent 65def81 commit 6aaf47f
Showing 1 changed file with 114 additions and 57 deletions.
171 changes: 114 additions & 57 deletions net/ipv4/udp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}

Expand All @@ -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);
Expand All @@ -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] +
Expand All @@ -181,29 +203,34 @@ 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)
goto fail;
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) &&
(*saddr_comp)(sk, sk2) )
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);
}
Expand Down Expand Up @@ -242,63 +269,78 @@ 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 (inet->rcv_saddr) {
if (inet->rcv_saddr != daddr)
continue;
score+=2;
}
if (inet->daddr) {
if (inet->daddr != saddr)
continue;
score+=2;
}
if (inet->dport) {
if (inet->dport != sport)
continue;
score+=2;
}
if (sk->sk_bound_dev_if) {
if (sk->sk_bound_dev_if != dif)
continue;
score+=2;
}
if (score == 9) {
result = sk;
break;
} else if (score > badness) {
result = sk;
badness = score;
}
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;
score+=2;
}
if (inet->daddr) {
if (inet->daddr != saddr)
continue;
score+=2;
}
if (inet->dport) {
if (inet->dport != sport)
continue;
score+=2;
}
if (sk->sk_bound_dev_if) {
if (sk->sk_bound_dev_if != dif)
continue;
score+=2;
}
if (score == 9) {
result = sk;
goto found;
} else if (score > best) {
result = sk;
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,
__be16 rmt_port, __be32 rmt_addr,
int dif)
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) ||
Expand Down Expand Up @@ -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;
Expand Down

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