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 0ee58dad5b06 ("net: tcp6: prefer listeners bound to an address")
and commit d9fbc7f6431f ("net: tcp: prefer listeners bound to an address"),
the TCP-SYN lookup fast path does not use listening_hash.

The commit 05c0b35709c5 ("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>

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 3908296..85cd695 100644 (file)
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -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,

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 103fc7a..1b87067 100644 (file)
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -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,

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 58421f9..eb8e128 100644 (file)
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -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;

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 581b5b2..b812eb3 100644 (file)
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -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);

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 4b00fcb..0b8235f 100644 (file)
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -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);
        }
 }
 

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b44fde4..028513d 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 918816e..218ad87 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -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);

diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 32ccac1..a758f2a 100644 (file)
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -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,

diff --git a/net/mptcp/mptcp_diag.c b/net/mptcp/mptcp_diag.c
index dbb6d87..7f9a717 100644 (file)
--- a/net/mptcp/mptcp_diag.c
+++ b/net/mptcp/mptcp_diag.c
@@ -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);