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net: inet: Retire port only listening_hash 

The listen sk is currently stored in two hash tables,
listening_hash (hashed by port) and lhash2 (hashed by port and address).

After commit 0ee58dad5b ("net: tcp6: prefer listeners bound to an address")
and commit d9fbc7f643 ("net: tcp: prefer listeners bound to an address"),
the TCP-SYN lookup fast path does not use listening_hash.

The commit 05c0b35709 ("tcp: seq_file: Replace listening_hash with lhash2")
also moved the seq_file (/proc/net/tcp) iteration usage from
listening_hash to lhash2.

There are still a few listening_hash usages left.
One of them is inet_reuseport_add_sock() which uses the listening_hash
to search a listen sk during the listen() system call.  This turns
out to be very slow on use cases that listen on many different
VIPs at a popular port (e.g. 443).  [ On top of the slowness in
adding to the tail in the IPv6 case ].  The latter patch has a
selftest to demonstrate this case.

This patch takes this chance to move all remaining listening_hash
usages to lhash2 and then retire listening_hash.

Since most changes need to be done together, it is hard to cut
the listening_hash to lhash2 switch into small patches.  The
changes in this patch is highlighted here for the review
purpose.

1. Because of the listening_hash removal, lhash2 can use the
   sk->sk_nulls_node instead of the icsk->icsk_listen_portaddr_node.
   This will also keep the sk_unhashed() check to work as is
   after stop adding sk to listening_hash.

   The union is removed from inet_listen_hashbucket because
   only nulls_head is needed.

2. icsk->icsk_listen_portaddr_node and its helpers are removed.

3. The current lhash2 users needs to iterate with sk_nulls_node
   instead of icsk_listen_portaddr_node.

   One case is in the inet[6]_lhash2_lookup().

   Another case is the seq_file iterator in tcp_ipv4.c.
   One thing to note is sk_nulls_next() is needed
   because the old inet_lhash2_for_each_icsk_continue()
   does a "next" first before iterating.

4. Move the remaining listening_hash usage to lhash2

   inet_reuseport_add_sock() which this series is
   trying to improve.

   inet_diag.c and mptcp_diag.c are the final two
   remaining use cases and is moved to lhash2 now also.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Martin KaFai Lau 2022-05-11 17:06:05 -07:00 committed by Jakub Kicinski
parent e8d0059000
commit cae3873c5b
9 changed files with 26 additions and 101 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/inet_connection_sock.h
View File

@ -66,7 +66,6 @@ struct inet_connection_sock_af_ops {
* @icsk_ulp_ops Pluggable ULP control hook
* @icsk_ulp_data ULP private data
* @icsk_clean_acked Clean acked data hook
* @icsk_listen_portaddr_node hash to the portaddr listener hashtable
* @icsk_ca_state: Congestion control state
* @icsk_retransmits: Number of unrecovered [RTO] timeouts
* @icsk_pending: Scheduled timer event
@ -96,7 +95,6 @@ struct inet_connection_sock {
const struct tcp_ulp_ops *icsk_ulp_ops;
void __rcu *icsk_ulp_data;
void (*icsk_clean_acked)(struct sock *sk, u32 acked_seq);
struct hlist_node icsk_listen_portaddr_node;
unsigned int (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
__u8 icsk_ca_state:5,
icsk_ca_initialized:1,

41
include/net/inet_hashtables.h
View File

@ -111,10 +111,7 @@ struct inet_bind_hashbucket {
#define LISTENING_NULLS_BASE (1U << 29)
struct inet_listen_hashbucket {
spinlock_t lock;
union {
struct hlist_head head;
struct hlist_nulls_head nulls_head;
};
struct hlist_nulls_head nulls_head;
};
/* This is for listening sockets, thus all sockets which possess wildcards. */
@ -142,32 +139,8 @@ struct inet_hashinfo {
/* The 2nd listener table hashed by local port and address */
unsigned int lhash2_mask;
struct inet_listen_hashbucket *lhash2;
/* All the above members are written once at bootup and
* never written again _or_ are predominantly read-access.
*
* Now align to a new cache line as all the following members
* might be often dirty.
*/
/* All sockets in TCP_LISTEN state will be in listening_hash.
* This is the only table where wildcard'd TCP sockets can
* exist. listening_hash is only hashed by local port number.
* If lhash2 is initialized, the same socket will also be hashed
* to lhash2 by port and address.
*/
struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE]
____cacheline_aligned_in_smp;
};
#define inet_lhash2_for_each_icsk_continue(__icsk) \
hlist_for_each_entry_continue(__icsk, icsk_listen_portaddr_node)
#define inet_lhash2_for_each_icsk(__icsk, list) \
hlist_for_each_entry(__icsk, list, icsk_listen_portaddr_node)
#define inet_lhash2_for_each_icsk_rcu(__icsk, list) \
hlist_for_each_entry_rcu(__icsk, list, icsk_listen_portaddr_node)
static inline struct inet_listen_hashbucket *
inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
{
@ -229,23 +202,11 @@ static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
const unsigned short snum);
/* These can have wildcards, don't try too hard. */
static inline u32 inet_lhashfn(const struct net *net, const unsigned short num)
{
return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
}
static inline int inet_sk_listen_hashfn(const struct sock *sk)
{
return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
}
/* Caller must disable local BH processing. */
int __inet_inherit_port(const struct sock *sk, struct sock *child);
void inet_put_port(struct sock *sk);
void inet_hashinfo_init(struct inet_hashinfo *h);
void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
unsigned long numentries, int scale,
unsigned long low_limit,

1
net/dccp/proto.c
View File

@ -1110,7 +1110,6 @@ static int __init dccp_init(void)
BUILD_BUG_ON(sizeof(struct dccp_skb_cb) >
sizeof_field(struct sk_buff, cb));
inet_hashinfo_init(&dccp_hashinfo);
rc = inet_hashinfo2_init_mod(&dccp_hashinfo);
if (rc)
goto out_fail;

5
net/ipv4/inet_diag.c
View File

@ -1028,12 +1028,13 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
if (!(idiag_states & TCPF_LISTEN) || r->id.idiag_dport)
goto skip_listen_ht;
for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
for (i = s_i; i <= hashinfo->lhash2_mask; i++) {
struct inet_listen_hashbucket *ilb;
struct hlist_nulls_node *node;
num = 0;
ilb = &hashinfo->listening_hash[i];
ilb = &hashinfo->lhash2[i];
spin_lock(&ilb->lock);
sk_nulls_for_each(sk, node, &ilb->nulls_head) {
struct inet_sock *inet = inet_sk(sk);

47
net/ipv4/inet_hashtables.c
View File

@ -246,12 +246,11 @@ static struct sock *inet_lhash2_lookup(struct net *net,
const __be32 daddr, const unsigned short hnum,
const int dif, const int sdif)
{
struct inet_connection_sock *icsk;
struct sock *sk, *result = NULL;
struct hlist_nulls_node *node;
int score, hiscore = 0;
inet_lhash2_for_each_icsk_rcu(icsk, &ilb2->head) {
sk = (struct sock *)icsk;
sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
score = compute_score(sk, net, hnum, daddr, dif, sdif);
if (score > hiscore) {
result = lookup_reuseport(net, sk, skb, doff,
@ -598,7 +597,6 @@ int __inet_hash(struct sock *sk, struct sock *osk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct inet_listen_hashbucket *ilb2;
struct inet_listen_hashbucket *ilb;
int err = 0;
if (sk->sk_state != TCP_LISTEN) {
@ -608,31 +606,23 @@ int __inet_hash(struct sock *sk, struct sock *osk)
return 0;
}
WARN_ON(!sk_unhashed(sk));
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
ilb2 = inet_lhash2_bucket_sk(hashinfo, sk);
spin_lock(&ilb->lock);
spin_lock(&ilb2->lock);
if (sk->sk_reuseport) {
err = inet_reuseport_add_sock(sk, ilb);
err = inet_reuseport_add_sock(sk, ilb2);
if (err)
goto unlock;
}
if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
sk->sk_family == AF_INET6) {
hlist_add_tail_rcu(&inet_csk(sk)->icsk_listen_portaddr_node,
&ilb2->head);
__sk_nulls_add_node_tail_rcu(sk, &ilb->nulls_head);
} else {
hlist_add_head_rcu(&inet_csk(sk)->icsk_listen_portaddr_node,
&ilb2->head);
__sk_nulls_add_node_rcu(sk, &ilb->nulls_head);
}
sk->sk_family == AF_INET6)
__sk_nulls_add_node_tail_rcu(sk, &ilb2->nulls_head);
else
__sk_nulls_add_node_rcu(sk, &ilb2->nulls_head);
sock_set_flag(sk, SOCK_RCU_FREE);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
unlock:
spin_unlock(&ilb2->lock);
spin_unlock(&ilb->lock);
return err;
}
@ -658,29 +648,23 @@ void inet_unhash(struct sock *sk)
if (sk->sk_state == TCP_LISTEN) {
struct inet_listen_hashbucket *ilb2;
struct inet_listen_hashbucket *ilb;
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
ilb2 = inet_lhash2_bucket_sk(hashinfo, sk);
/* Don't disable bottom halves while acquiring the lock to
* avoid circular locking dependency on PREEMPT_RT.
*/
spin_lock(&ilb->lock);
spin_lock(&ilb2->lock);
if (sk_unhashed(sk)) {
spin_unlock(&ilb2->lock);
spin_unlock(&ilb->lock);
return;
}
if (rcu_access_pointer(sk->sk_reuseport_cb))
reuseport_stop_listen_sock(sk);
hlist_del_init_rcu(&inet_csk(sk)->icsk_listen_portaddr_node);
__sk_nulls_del_node_init_rcu(sk);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_unlock(&ilb2->lock);
spin_unlock(&ilb->lock);
} else {
spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
@ -848,27 +832,14 @@ int inet_hash_connect(struct inet_timewait_death_row *death_row,
}
EXPORT_SYMBOL_GPL(inet_hash_connect);
void inet_hashinfo_init(struct inet_hashinfo *h)
{
int i;
for (i = 0; i < INET_LHTABLE_SIZE; i++) {
spin_lock_init(&h->listening_hash[i].lock);
INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].nulls_head,
i + LISTENING_NULLS_BASE);
}
h->lhash2 = NULL;
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);
static void init_hashinfo_lhash2(struct inet_hashinfo *h)
{
int i;
for (i = 0; i <= h->lhash2_mask; i++) {
spin_lock_init(&h->lhash2[i].lock);
INIT_HLIST_HEAD(&h->lhash2[i].head);
INIT_HLIST_NULLS_HEAD(&h->lhash2[i].nulls_head,
i + LISTENING_NULLS_BASE);
}
}

1
net/ipv4/tcp.c
View File

@ -4595,7 +4595,6 @@ void __init tcp_init(void)
timer_setup(&tcp_orphan_timer, tcp_orphan_update, TIMER_DEFERRABLE);
mod_timer(&tcp_orphan_timer, jiffies + TCP_ORPHAN_TIMER_PERIOD);
inet_hashinfo_init(&tcp_hashinfo);
inet_hashinfo2_init(&tcp_hashinfo, "tcp_listen_portaddr_hash",
thash_entries, 21, /* one slot per 2 MB*/
0, 64 * 1024);

21
net/ipv4/tcp_ipv4.c
View File

@ -2283,16 +2283,15 @@ static void *listening_get_first(struct seq_file *seq)
st->offset = 0;
for (; st->bucket <= tcp_hashinfo.lhash2_mask; st->bucket++) {
struct inet_listen_hashbucket *ilb2;
struct inet_connection_sock *icsk;
struct hlist_nulls_node *node;
struct sock *sk;
ilb2 = &tcp_hashinfo.lhash2[st->bucket];
if (hlist_empty(&ilb2->head))
if (hlist_nulls_empty(&ilb2->nulls_head))
continue;
spin_lock(&ilb2->lock);
inet_lhash2_for_each_icsk(icsk, &ilb2->head) {
sk = (struct sock *)icsk;
sk_nulls_for_each(sk, node, &ilb2->nulls_head) {
if (seq_sk_match(seq, sk))
return sk;
}
@ -2311,15 +2310,14 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
{
struct tcp_iter_state *st = seq->private;
struct inet_listen_hashbucket *ilb2;
struct inet_connection_sock *icsk;
struct hlist_nulls_node *node;
struct sock *sk = cur;
++st->num;
++st->offset;
icsk = inet_csk(sk);
inet_lhash2_for_each_icsk_continue(icsk) {
sk = (struct sock *)icsk;
sk = sk_nulls_next(sk);
sk_nulls_for_each_from(sk, node) {
if (seq_sk_match(seq, sk))
return sk;
}
@ -2728,16 +2726,15 @@ static unsigned int bpf_iter_tcp_listening_batch(struct seq_file *seq,
{
struct bpf_tcp_iter_state *iter = seq->private;
struct tcp_iter_state *st = &iter->state;
struct inet_connection_sock *icsk;
struct hlist_nulls_node *node;
unsigned int expected = 1;
struct sock *sk;
sock_hold(start_sk);
iter->batch[iter->end_sk++] = start_sk;
icsk = inet_csk(start_sk);
inet_lhash2_for_each_icsk_continue(icsk) {
sk = (struct sock *)icsk;
sk = sk_nulls_next(start_sk);
sk_nulls_for_each_from(sk, node) {
if (seq_sk_match(seq, sk)) {
if (iter->end_sk < iter->max_sk) {
sock_hold(sk);

5
net/ipv6/inet6_hashtables.c
View File

@ -138,12 +138,11 @@ static struct sock *inet6_lhash2_lookup(struct net *net,
const __be16 sport, const struct in6_addr *daddr,
const unsigned short hnum, const int dif, const int sdif)
{
struct inet_connection_sock *icsk;
struct sock *sk, *result = NULL;
struct hlist_nulls_node *node;
int score, hiscore = 0;
inet_lhash2_for_each_icsk_rcu(icsk, &ilb2->head) {
sk = (struct sock *)icsk;
sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
score = compute_score(sk, net, hnum, daddr, dif, sdif);
if (score > hiscore) {
result = lookup_reuseport(net, sk, skb, doff,

4
net/mptcp/mptcp_diag.c
View File

@ -83,13 +83,13 @@ static void mptcp_diag_dump_listeners(struct sk_buff *skb, struct netlink_callba
struct net *net = sock_net(skb->sk);
int i;
for (i = diag_ctx->l_slot; i < INET_LHTABLE_SIZE; i++) {
for (i = diag_ctx->l_slot; i <= tcp_hashinfo.lhash2_mask; i++) {
struct inet_listen_hashbucket *ilb;
struct hlist_nulls_node *node;
struct sock *sk;
int num = 0;
ilb = &tcp_hashinfo.listening_hash[i];
ilb = &tcp_hashinfo.lhash2[i];
rcu_read_lock();
spin_lock(&ilb->lock);