diff options
Diffstat (limited to 'include/net/inet_hashtables.h')
| -rw-r--r-- | include/net/inet_hashtables.h | 439 |
1 files changed, 439 insertions, 0 deletions
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h new file mode 100644 index 000000000000..f50f95968340 --- /dev/null +++ b/include/net/inet_hashtables.h @@ -0,0 +1,439 @@ +/* + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * Authors: Lotsa people, from code originally in tcp + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#ifndef _INET_HASHTABLES_H +#define _INET_HASHTABLES_H + +#include <linux/config.h> + +#include <linux/interrupt.h> +#include <linux/ipv6.h> +#include <linux/list.h> +#include <linux/slab.h> +#include <linux/socket.h> +#include <linux/spinlock.h> +#include <linux/types.h> +#include <linux/wait.h> + +#include <net/inet_connection_sock.h> +#include <net/route.h> +#include <net/sock.h> +#include <net/tcp_states.h> + +#include <asm/atomic.h> +#include <asm/byteorder.h> + +/* This is for all connections with a full identity, no wildcards. + * New scheme, half the table is for TIME_WAIT, the other half is + * for the rest. I'll experiment with dynamic table growth later. + */ +struct inet_ehash_bucket { + rwlock_t lock; + struct hlist_head chain; +}; + +/* There are a few simple rules, which allow for local port reuse by + * an application. In essence: + * + * 1) Sockets bound to different interfaces may share a local port. + * Failing that, goto test 2. + * 2) If all sockets have sk->sk_reuse set, and none of them are in + * TCP_LISTEN state, the port may be shared. + * Failing that, goto test 3. + * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local + * address, and none of them are the same, the port may be + * shared. + * Failing this, the port cannot be shared. + * + * The interesting point, is test #2. This is what an FTP server does + * all day. To optimize this case we use a specific flag bit defined + * below. As we add sockets to a bind bucket list, we perform a + * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) + * As long as all sockets added to a bind bucket pass this test, + * the flag bit will be set. + * The resulting situation is that tcp_v[46]_verify_bind() can just check + * for this flag bit, if it is set and the socket trying to bind has + * sk->sk_reuse set, we don't even have to walk the owners list at all, + * we return that it is ok to bind this socket to the requested local port. + * + * Sounds like a lot of work, but it is worth it. In a more naive + * implementation (ie. current FreeBSD etc.) the entire list of ports + * must be walked for each data port opened by an ftp server. Needless + * to say, this does not scale at all. With a couple thousand FTP + * users logged onto your box, isn't it nice to know that new data + * ports are created in O(1) time? I thought so. ;-) -DaveM + */ +struct inet_bind_bucket { + unsigned short port; + signed short fastreuse; + struct hlist_node node; + struct hlist_head owners; +}; + +#define inet_bind_bucket_for_each(tb, node, head) \ + hlist_for_each_entry(tb, node, head, node) + +struct inet_bind_hashbucket { + spinlock_t lock; + struct hlist_head chain; +}; + +/* This is for listening sockets, thus all sockets which possess wildcards. */ +#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ + +struct inet_hashinfo { + /* This is for sockets with full identity only. Sockets here will + * always be without wildcards and will have the following invariant: + * + * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE + * + * First half of the table is for sockets not in TIME_WAIT, second half + * is for TIME_WAIT sockets only. + */ + struct inet_ehash_bucket *ehash; + + /* Ok, let's try this, I give up, we do need a local binding + * TCP hash as well as the others for fast bind/connect. + */ + struct inet_bind_hashbucket *bhash; + + int bhash_size; + unsigned int ehash_size; + + /* 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]; + + /* 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. + */ + rwlock_t lhash_lock ____cacheline_aligned; + atomic_t lhash_users; + wait_queue_head_t lhash_wait; + spinlock_t portalloc_lock; + kmem_cache_t *bind_bucket_cachep; + int port_rover; +}; + +static inline unsigned int inet_ehashfn(const __u32 laddr, const __u16 lport, + const __u32 faddr, const __u16 fport) +{ + unsigned int h = (laddr ^ lport) ^ (faddr ^ fport); + h ^= h >> 16; + h ^= h >> 8; + return h; +} + +static inline int inet_sk_ehashfn(const struct sock *sk) +{ + const struct inet_sock *inet = inet_sk(sk); + const __u32 laddr = inet->rcv_saddr; + const __u16 lport = inet->num; + const __u32 faddr = inet->daddr; + const __u16 fport = inet->dport; + + return inet_ehashfn(laddr, lport, faddr, fport); +} + +static inline struct inet_ehash_bucket *inet_ehash_bucket( + struct inet_hashinfo *hashinfo, + unsigned int hash) +{ + return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; +} + +extern struct inet_bind_bucket * + inet_bind_bucket_create(kmem_cache_t *cachep, + struct inet_bind_hashbucket *head, + const unsigned short snum); +extern void inet_bind_bucket_destroy(kmem_cache_t *cachep, + struct inet_bind_bucket *tb); + +static inline int inet_bhashfn(const __u16 lport, const int bhash_size) +{ + return lport & (bhash_size - 1); +} + +extern 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 int inet_lhashfn(const unsigned short num) +{ + return num & (INET_LHTABLE_SIZE - 1); +} + +static inline int inet_sk_listen_hashfn(const struct sock *sk) +{ + return inet_lhashfn(inet_sk(sk)->num); +} + +/* Caller must disable local BH processing. */ +static inline void __inet_inherit_port(struct inet_hashinfo *table, + struct sock *sk, struct sock *child) +{ + const int bhash = inet_bhashfn(inet_sk(child)->num, table->bhash_size); + struct inet_bind_hashbucket *head = &table->bhash[bhash]; + struct inet_bind_bucket *tb; + + spin_lock(&head->lock); + tb = inet_csk(sk)->icsk_bind_hash; + sk_add_bind_node(child, &tb->owners); + inet_csk(child)->icsk_bind_hash = tb; + spin_unlock(&head->lock); +} + +static inline void inet_inherit_port(struct inet_hashinfo *table, + struct sock *sk, struct sock *child) +{ + local_bh_disable(); + __inet_inherit_port(table, sk, child); + local_bh_enable(); +} + +extern void inet_put_port(struct inet_hashinfo *table, 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); +} + +static inline void __inet_hash(struct inet_hashinfo *hashinfo, + struct sock *sk, const int listen_possible) +{ + struct hlist_head *list; + rwlock_t *lock; + + BUG_TRAP(sk_unhashed(sk)); + if (listen_possible && sk->sk_state == TCP_LISTEN) { + list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; + lock = &hashinfo->lhash_lock; + inet_listen_wlock(hashinfo); + } else { + struct inet_ehash_bucket *head; + sk->sk_hash = inet_sk_ehashfn(sk); + head = inet_ehash_bucket(hashinfo, sk->sk_hash); + list = &head->chain; + lock = &head->lock; + write_lock(lock); + } + __sk_add_node(sk, list); + sock_prot_inc_use(sk->sk_prot); + write_unlock(lock); + if (listen_possible && sk->sk_state == TCP_LISTEN) + wake_up(&hashinfo->lhash_wait); +} + +static inline void inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk) +{ + if (sk->sk_state != TCP_CLOSE) { + local_bh_disable(); + __inet_hash(hashinfo, sk, 1); + local_bh_enable(); + } +} + +static inline void inet_unhash(struct inet_hashinfo *hashinfo, struct sock *sk) +{ + rwlock_t *lock; + + if (sk_unhashed(sk)) + goto out; + + if (sk->sk_state == TCP_LISTEN) { + local_bh_disable(); + inet_listen_wlock(hashinfo); + lock = &hashinfo->lhash_lock; + } else { + lock = &inet_ehash_bucket(hashinfo, sk->sk_hash)->lock; + write_lock_bh(lock); + } + + if (__sk_del_node_init(sk)) + sock_prot_dec_use(sk->sk_prot); + write_unlock_bh(lock); +out: + if (sk->sk_state == TCP_LISTEN) + wake_up(&hashinfo->lhash_wait); +} + +static inline int inet_iif(const struct sk_buff *skb) +{ + return ((struct rtable *)skb->dst)->rt_iif; +} + +extern struct sock *__inet_lookup_listener(const struct hlist_head *head, + const u32 daddr, + const unsigned short hnum, + const int dif); + +/* Optimize the common listener case. */ +static inline struct sock * + inet_lookup_listener(struct inet_hashinfo *hashinfo, + const u32 daddr, + const unsigned short hnum, const int dif) +{ + struct sock *sk = NULL; + const struct hlist_head *head; + + read_lock(&hashinfo->lhash_lock); + head = &hashinfo->listening_hash[inet_lhashfn(hnum)]; + if (!hlist_empty(head)) { + const struct inet_sock *inet = inet_sk((sk = __sk_head(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) + goto sherry_cache; + sk = __inet_lookup_listener(head, daddr, hnum, dif); + } + if (sk) { +sherry_cache: + sock_hold(sk); + } + read_unlock(&hashinfo->lhash_lock); + return sk; +} + +/* Socket demux engine toys. */ +#ifdef __BIG_ENDIAN +#define INET_COMBINED_PORTS(__sport, __dport) \ + (((__u32)(__sport) << 16) | (__u32)(__dport)) +#else /* __LITTLE_ENDIAN */ +#define INET_COMBINED_PORTS(__sport, __dport) \ + (((__u32)(__dport) << 16) | (__u32)(__sport)) +#endif + +#if (BITS_PER_LONG == 64) +#ifdef __BIG_ENDIAN +#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ + const __u64 __name = (((__u64)(__saddr)) << 32) | ((__u64)(__daddr)); +#else /* __LITTLE_ENDIAN */ +#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ + const __u64 __name = (((__u64)(__daddr)) << 32) | ((__u64)(__saddr)); +#endif /* __BIG_ENDIAN */ +#define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ + (((__sk)->sk_hash == (__hash)) && \ + ((*((__u64 *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ + ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ + (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) +#define INET_TW_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ + (((__sk)->sk_hash == (__hash)) && \ + ((*((__u64 *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ + ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ + (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) +#else /* 32-bit arch */ +#define INET_ADDR_COOKIE(__name, __saddr, __daddr) +#define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ + (((__sk)->sk_hash == (__hash)) && \ + (inet_sk(__sk)->daddr == (__saddr)) && \ + (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ + ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ + (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) +#define INET_TW_MATCH(__sk, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ + (((__sk)->sk_hash == (__hash)) && \ + (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ + (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ + ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ + (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) +#endif /* 64-bit arch */ + +/* + * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need + * not check it for lookups anymore, thanks Alexey. -DaveM + * + * Local BH must be disabled here. + */ +static inline struct sock * + __inet_lookup_established(struct inet_hashinfo *hashinfo, + const u32 saddr, const u16 sport, + const u32 daddr, const u16 hnum, + const int dif) +{ + INET_ADDR_COOKIE(acookie, saddr, daddr) + const __u32 ports = INET_COMBINED_PORTS(sport, hnum); + struct sock *sk; + const struct hlist_node *node; + /* Optimize here for direct hit, only listening connections can + * have wildcards anyways. + */ + unsigned int hash = inet_ehashfn(daddr, hnum, saddr, sport); + struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash); + + prefetch(head->chain.first); + read_lock(&head->lock); + sk_for_each(sk, node, &head->chain) { + if (INET_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) + goto hit; /* You sunk my battleship! */ + } + + /* Must check for a TIME_WAIT'er before going to listener hash. */ + sk_for_each(sk, node, &(head + hashinfo->ehash_size)->chain) { + if (INET_TW_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) + goto hit; + } + sk = NULL; +out: + read_unlock(&head->lock); + return sk; +hit: + sock_hold(sk); + goto out; +} + +static inline struct sock *__inet_lookup(struct inet_hashinfo *hashinfo, + const u32 saddr, const u16 sport, + const u32 daddr, const u16 hnum, + const int dif) +{ + struct sock *sk = __inet_lookup_established(hashinfo, saddr, sport, daddr, + hnum, dif); + return sk ? : inet_lookup_listener(hashinfo, daddr, hnum, dif); +} + +static inline struct sock *inet_lookup(struct inet_hashinfo *hashinfo, + const u32 saddr, const u16 sport, + const u32 daddr, const u16 dport, + const int dif) +{ + struct sock *sk; + + local_bh_disable(); + sk = __inet_lookup(hashinfo, saddr, sport, daddr, ntohs(dport), dif); + local_bh_enable(); + + return sk; +} +#endif /* _INET_HASHTABLES_H */ |