include/net/inet_hashtables.h - SHIFTPHONES/mainline/linux - Gitiles

 /*
  * 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/interrupt.h>
 #include <linux/ip.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/sock.h>
 #include <net/tcp_states.h>

 #include <asm/atomic.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;
 } __attribute__((__aligned__(8)));

 /* 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;
 	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 int inet_ehashfn(const __u32 laddr, const __u16 lport,
 			       const __u32 faddr, const __u16 fport,
 			       const int ehash_size)
 {
 	int h = (laddr ^ lport) ^ (faddr ^ fport);
 	h ^= h >> 16;
 	h ^= h >> 8;
 	return h & (ehash_size - 1);
 }

 static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size)
 {
 	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, ehash_size);
 }

 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_sk(sk)->bind_hash;
 	sk_add_bind_node(child, &tb->owners);
 	inet_sk(child)->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 {
 		sk->sk_hashent = inet_sk_ehashfn(sk, hashinfo->ehash_size);
 		list = &hashinfo->ehash[sk->sk_hashent].chain;
 		lock = &hashinfo->ehash[sk->sk_hashent].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 {
 		struct inet_ehash_bucket *head = &hashinfo->ehash[sk->sk_hashent];
 		lock = &head->lock;
 		write_lock_bh(&head->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);
 }

 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;
 	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;
 }
 #endif /* _INET_HASHTABLES_H */
	/*
	* 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/interrupt.h>
	#include <linux/ip.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/sock.h>
	#include <net/tcp_states.h>

	#include <asm/atomic.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;
	} __attribute__((__aligned__(8)));

	/* 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;
	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 int inet_ehashfn(const __u32 laddr, const __u16 lport,
	const __u32 faddr, const __u16 fport,
	const int ehash_size)
	{
	int h = (laddr ^ lport) ^ (faddr ^ fport);
	h ^= h >> 16;
	h ^= h >> 8;
	return h & (ehash_size - 1);
	}

	static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size)
	{
	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, ehash_size);
	}

	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_sk(sk)->bind_hash;
	sk_add_bind_node(child, &tb->owners);
	inet_sk(child)->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 {
	sk->sk_hashent = inet_sk_ehashfn(sk, hashinfo->ehash_size);
	list = &hashinfo->ehash[sk->sk_hashent].chain;
	lock = &hashinfo->ehash[sk->sk_hashent].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 {
	struct inet_ehash_bucket *head = &hashinfo->ehash[sk->sk_hashent];
	lock = &head->lock;
	write_lock_bh(&head->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);
	}

	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;
	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;
	}
	#endif /* _INET_HASHTABLES_H */