From 5caea4ea7088e80ac5410d04660346094608b909 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 20 Nov 2008 00:40:07 -0800 Subject: [PATCH] net: listening_hash get a spinlock per bucket This patch prepares RCU migration of listening_hash table for TCP/DCCP protocols. listening_hash table being small (32 slots per protocol), we add a spinlock for each slot, instead of a single rwlock for whole table. This should reduce hold time of readers, and writers concurrency. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/inet_hashtables.h | 45 ++++++++-------------- net/dccp/proto.c | 8 +--- net/ipv4/inet_diag.c | 12 +++--- net/ipv4/inet_hashtables.c | 86 ++++++++++++++++--------------------------- net/ipv4/tcp_ipv4.c | 24 ++++++------ net/ipv6/inet6_hashtables.c | 23 ++++++------ 6 files changed, 79 insertions(+), 119 deletions(-) diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 4818960..62d2dd0d 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -99,6 +99,11 @@ struct inet_bind_hashbucket { struct hlist_head chain; }; +struct inet_listen_hashbucket { + spinlock_t lock; + struct hlist_head head; +}; + /* This is for listening sockets, thus all sockets which possess wildcards. */ #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ @@ -123,22 +128,21 @@ struct inet_hashinfo { unsigned int bhash_size; /* Note : 4 bytes padding on 64 bit arches */ - /* All sockets in TCP_LISTEN state will be in here. This is the only - * table where wildcard'd TCP sockets can exist. Hash function here - * is just local port number. - */ - struct hlist_head listening_hash[INET_LHTABLE_SIZE]; + struct kmem_cache *bind_bucket_cachep; /* 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 - * are often dirty. + * might be often dirty. + */ + /* All sockets in TCP_LISTEN state will be in here. This is the only + * table where wildcard'd TCP sockets can exist. Hash function here + * is just local port number. */ - rwlock_t lhash_lock ____cacheline_aligned; - atomic_t lhash_users; - wait_queue_head_t lhash_wait; - struct kmem_cache *bind_bucket_cachep; + struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE] + ____cacheline_aligned_in_smp; + }; static inline struct inet_ehash_bucket *inet_ehash_bucket( @@ -236,26 +240,7 @@ extern void __inet_inherit_port(struct sock *sk, struct sock *child); extern void inet_put_port(struct sock *sk); -extern void inet_listen_wlock(struct inet_hashinfo *hashinfo); - -/* - * - We may sleep inside this lock. - * - If sleeping is not required (or called from BH), - * use plain read_(un)lock(&inet_hashinfo.lhash_lock). - */ -static inline void inet_listen_lock(struct inet_hashinfo *hashinfo) -{ - /* read_lock synchronizes to candidates to writers */ - read_lock(&hashinfo->lhash_lock); - atomic_inc(&hashinfo->lhash_users); - read_unlock(&hashinfo->lhash_lock); -} - -static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo) -{ - if (atomic_dec_and_test(&hashinfo->lhash_users)) - wake_up(&hashinfo->lhash_wait); -} +void inet_hashinfo_init(struct inet_hashinfo *h); extern void __inet_hash_nolisten(struct sock *sk); extern void inet_hash(struct sock *sk); diff --git a/net/dccp/proto.c b/net/dccp/proto.c index bdf784c..8b63394 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -44,12 +44,7 @@ atomic_t dccp_orphan_count = ATOMIC_INIT(0); EXPORT_SYMBOL_GPL(dccp_orphan_count); -struct inet_hashinfo __cacheline_aligned dccp_hashinfo = { - .lhash_lock = RW_LOCK_UNLOCKED, - .lhash_users = ATOMIC_INIT(0), - .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(dccp_hashinfo.lhash_wait), -}; - +struct inet_hashinfo dccp_hashinfo; EXPORT_SYMBOL_GPL(dccp_hashinfo); /* the maximum queue length for tx in packets. 0 is no limit */ @@ -1030,6 +1025,7 @@ static int __init dccp_init(void) BUILD_BUG_ON(sizeof(struct dccp_skb_cb) > FIELD_SIZEOF(struct sk_buff, cb)); + inet_hashinfo_init(&dccp_hashinfo); dccp_hashinfo.bind_bucket_cachep = kmem_cache_create("dccp_bind_bucket", sizeof(struct inet_bind_bucket), 0, diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c index 41b3672..1cb154e 100644 --- a/net/ipv4/inet_diag.c +++ b/net/ipv4/inet_diag.c @@ -718,13 +718,15 @@ static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) if (!(r->idiag_states & (TCPF_LISTEN | TCPF_SYN_RECV))) goto skip_listen_ht; - inet_listen_lock(hashinfo); for (i = s_i; i < INET_LHTABLE_SIZE; i++) { struct sock *sk; struct hlist_node *node; + struct inet_listen_hashbucket *ilb; num = 0; - sk_for_each(sk, node, &hashinfo->listening_hash[i]) { + ilb = &hashinfo->listening_hash[i]; + spin_lock_bh(&ilb->lock); + sk_for_each(sk, node, &ilb->head) { struct inet_sock *inet = inet_sk(sk); if (num < s_num) { @@ -742,7 +744,7 @@ static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) goto syn_recv; if (inet_csk_diag_dump(sk, skb, cb) < 0) { - inet_listen_unlock(hashinfo); + spin_unlock_bh(&ilb->lock); goto done; } @@ -751,7 +753,7 @@ syn_recv: goto next_listen; if (inet_diag_dump_reqs(skb, sk, cb) < 0) { - inet_listen_unlock(hashinfo); + spin_unlock_bh(&ilb->lock); goto done; } @@ -760,12 +762,12 @@ next_listen: cb->args[4] = 0; ++num; } + spin_unlock_bh(&ilb->lock); s_num = 0; cb->args[3] = 0; cb->args[4] = 0; } - inet_listen_unlock(hashinfo); skip_listen_ht: cb->args[0] = 1; s_i = num = s_num = 0; diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index fd269cf..377d004 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -111,35 +111,6 @@ void __inet_inherit_port(struct sock *sk, struct sock *child) EXPORT_SYMBOL_GPL(__inet_inherit_port); /* - * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP. - * Look, when several writers sleep and reader wakes them up, all but one - * immediately hit write lock and grab all the cpus. Exclusive sleep solves - * this, _but_ remember, it adds useless work on UP machines (wake up each - * exclusive lock release). It should be ifdefed really. - */ -void inet_listen_wlock(struct inet_hashinfo *hashinfo) - __acquires(hashinfo->lhash_lock) -{ - write_lock(&hashinfo->lhash_lock); - - if (atomic_read(&hashinfo->lhash_users)) { - DEFINE_WAIT(wait); - - for (;;) { - prepare_to_wait_exclusive(&hashinfo->lhash_wait, - &wait, TASK_UNINTERRUPTIBLE); - if (!atomic_read(&hashinfo->lhash_users)) - break; - write_unlock_bh(&hashinfo->lhash_lock); - schedule(); - write_lock_bh(&hashinfo->lhash_lock); - } - - finish_wait(&hashinfo->lhash_wait, &wait); - } -} - -/* * Don't inline this cruft. Here are some nice properties to exploit here. The * BSD API does not allow a listening sock to specify the remote port nor the * remote address for the connection. So always assume those are both @@ -191,25 +162,25 @@ struct sock *__inet_lookup_listener(struct net *net, const int dif) { struct sock *sk = NULL; - const struct hlist_head *head; + struct inet_listen_hashbucket *ilb; - read_lock(&hashinfo->lhash_lock); - head = &hashinfo->listening_hash[inet_lhashfn(net, hnum)]; - if (!hlist_empty(head)) { - const struct inet_sock *inet = inet_sk((sk = __sk_head(head))); + ilb = &hashinfo->listening_hash[inet_lhashfn(net, hnum)]; + spin_lock(&ilb->lock); + if (!hlist_empty(&ilb->head)) { + const struct inet_sock *inet = inet_sk((sk = __sk_head(&ilb->head))); if (inet->num == hnum && !sk->sk_node.next && (!inet->rcv_saddr || inet->rcv_saddr == daddr) && (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) && !sk->sk_bound_dev_if && net_eq(sock_net(sk), net)) goto sherry_cache; - sk = inet_lookup_listener_slow(net, head, daddr, hnum, dif); + sk = inet_lookup_listener_slow(net, &ilb->head, daddr, hnum, dif); } if (sk) { sherry_cache: sock_hold(sk); } - read_unlock(&hashinfo->lhash_lock); + spin_unlock(&ilb->lock); return sk; } EXPORT_SYMBOL_GPL(__inet_lookup_listener); @@ -389,8 +360,7 @@ EXPORT_SYMBOL_GPL(__inet_hash_nolisten); static void __inet_hash(struct sock *sk) { struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo; - struct hlist_head *list; - rwlock_t *lock; + struct inet_listen_hashbucket *ilb; if (sk->sk_state != TCP_LISTEN) { __inet_hash_nolisten(sk); @@ -398,14 +368,12 @@ static void __inet_hash(struct sock *sk) } WARN_ON(!sk_unhashed(sk)); - list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; - lock = &hashinfo->lhash_lock; + ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; - inet_listen_wlock(hashinfo); - __sk_add_node(sk, list); + spin_lock(&ilb->lock); + __sk_add_node(sk, &ilb->head); sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1); - write_unlock(lock); - wake_up(&hashinfo->lhash_wait); + spin_unlock(&ilb->lock); } void inet_hash(struct sock *sk) @@ -420,29 +388,27 @@ EXPORT_SYMBOL_GPL(inet_hash); void inet_unhash(struct sock *sk) { - rwlock_t *lock; struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo; if (sk_unhashed(sk)) - goto out; + return; if (sk->sk_state == TCP_LISTEN) { - local_bh_disable(); - inet_listen_wlock(hashinfo); - lock = &hashinfo->lhash_lock; + struct inet_listen_hashbucket *ilb; + + ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; + spin_lock_bh(&ilb->lock); if (__sk_del_node_init(sk)) sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); + spin_unlock_bh(&ilb->lock); } else { - lock = inet_ehash_lockp(hashinfo, sk->sk_hash); + rwlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); + write_lock_bh(lock); if (__sk_nulls_del_node_init_rcu(sk)) sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); + write_unlock_bh(lock); } - - write_unlock_bh(lock); -out: - if (sk->sk_state == TCP_LISTEN) - wake_up(&hashinfo->lhash_wait); } EXPORT_SYMBOL_GPL(inet_unhash); @@ -556,3 +522,13 @@ 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); +} + +EXPORT_SYMBOL_GPL(inet_hashinfo_init); diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 5559fea..330b08a 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -97,11 +97,7 @@ struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr) } #endif -struct inet_hashinfo __cacheline_aligned tcp_hashinfo = { - .lhash_lock = __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock), - .lhash_users = ATOMIC_INIT(0), - .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait), -}; +struct inet_hashinfo tcp_hashinfo; static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb) { @@ -1874,15 +1870,18 @@ static void *listening_get_next(struct seq_file *seq, void *cur) struct inet_connection_sock *icsk; struct hlist_node *node; struct sock *sk = cur; + struct inet_listen_hashbucket *ilb; struct tcp_iter_state *st = seq->private; struct net *net = seq_file_net(seq); if (!sk) { st->bucket = 0; - sk = sk_head(&tcp_hashinfo.listening_hash[0]); + ilb = &tcp_hashinfo.listening_hash[0]; + spin_lock_bh(&ilb->lock); + sk = sk_head(&ilb->head); goto get_sk; } - + ilb = &tcp_hashinfo.listening_hash[st->bucket]; ++st->num; if (st->state == TCP_SEQ_STATE_OPENREQ) { @@ -1932,8 +1931,11 @@ start_req: } read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); } + spin_unlock_bh(&ilb->lock); if (++st->bucket < INET_LHTABLE_SIZE) { - sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]); + ilb = &tcp_hashinfo.listening_hash[st->bucket]; + spin_lock_bh(&ilb->lock); + sk = sk_head(&ilb->head); goto get_sk; } cur = NULL; @@ -2066,12 +2068,10 @@ static void *tcp_get_idx(struct seq_file *seq, loff_t pos) void *rc; struct tcp_iter_state *st = seq->private; - inet_listen_lock(&tcp_hashinfo); st->state = TCP_SEQ_STATE_LISTENING; rc = listening_get_idx(seq, &pos); if (!rc) { - inet_listen_unlock(&tcp_hashinfo); st->state = TCP_SEQ_STATE_ESTABLISHED; rc = established_get_idx(seq, pos); } @@ -2103,7 +2103,6 @@ static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos) case TCP_SEQ_STATE_LISTENING: rc = listening_get_next(seq, v); if (!rc) { - inet_listen_unlock(&tcp_hashinfo); st->state = TCP_SEQ_STATE_ESTABLISHED; rc = established_get_first(seq); } @@ -2130,7 +2129,7 @@ static void tcp_seq_stop(struct seq_file *seq, void *v) } case TCP_SEQ_STATE_LISTENING: if (v != SEQ_START_TOKEN) - inet_listen_unlock(&tcp_hashinfo); + spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock); break; case TCP_SEQ_STATE_TIME_WAIT: case TCP_SEQ_STATE_ESTABLISHED: @@ -2405,6 +2404,7 @@ static struct pernet_operations __net_initdata tcp_sk_ops = { void __init tcp_v4_init(void) { + inet_hashinfo_init(&tcp_hashinfo); if (register_pernet_device(&tcp_sk_ops)) panic("Failed to create the TCP control socket.\n"); } diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index c1b4d40..21544b9 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -25,30 +25,30 @@ void __inet6_hash(struct sock *sk) { struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo; - rwlock_t *lock; WARN_ON(!sk_unhashed(sk)); if (sk->sk_state == TCP_LISTEN) { - struct hlist_head *list; + struct inet_listen_hashbucket *ilb; - list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; - lock = &hashinfo->lhash_lock; - inet_listen_wlock(hashinfo); - __sk_add_node(sk, list); + ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; + spin_lock(&ilb->lock); + __sk_add_node(sk, &ilb->head); + spin_unlock(&ilb->lock); } else { unsigned int hash; struct hlist_nulls_head *list; + rwlock_t *lock; sk->sk_hash = hash = inet6_sk_ehashfn(sk); list = &inet_ehash_bucket(hashinfo, hash)->chain; lock = inet_ehash_lockp(hashinfo, hash); write_lock(lock); __sk_nulls_add_node_rcu(sk, list); + write_unlock(lock); } sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1); - write_unlock(lock); } EXPORT_SYMBOL(__inet6_hash); @@ -126,10 +126,11 @@ struct sock *inet6_lookup_listener(struct net *net, const struct hlist_node *node; struct sock *result = NULL; int score, hiscore = 0; + struct inet_listen_hashbucket *ilb; - read_lock(&hashinfo->lhash_lock); - sk_for_each(sk, node, - &hashinfo->listening_hash[inet_lhashfn(net, hnum)]) { + ilb = &hashinfo->listening_hash[inet_lhashfn(net, hnum)]; + spin_lock(&ilb->lock); + sk_for_each(sk, node, &ilb->head) { if (net_eq(sock_net(sk), net) && inet_sk(sk)->num == hnum && sk->sk_family == PF_INET6) { const struct ipv6_pinfo *np = inet6_sk(sk); @@ -157,7 +158,7 @@ struct sock *inet6_lookup_listener(struct net *net, } if (result) sock_hold(result); - read_unlock(&hashinfo->lhash_lock); + spin_unlock(&ilb->lock); return result; } -- 2.7.4