1 files changed, 427 insertions, 0 deletions
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
new file mode 100644
index 00000000000..646b6ea7fe2
--- /dev/null
+++ b/include/net/inet_hashtables.h
@@ -0,0 +1,427 @@
+/*
+ * 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;
+} __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_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 {
+		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);
+}
+
+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, __cookie, __saddr, __daddr, __ports, __dif)\
+	(((*((__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, __cookie, __saddr, __daddr, __ports, __dif)\
+	(((*((__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, __cookie, __saddr, __daddr, __ports, __dif)	\
+	((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, __cookie, __saddr, __daddr, __ports, __dif)	\
+	((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.
+	 */
+	const int hash = inet_ehashfn(daddr, hnum, saddr, sport, hashinfo->ehash_size);
+	struct inet_ehash_bucket *head = &hashinfo->ehash[hash];
+
+	read_lock(&head->lock);
+	sk_for_each(sk, node, &head->chain) {
+		if (INET_MATCH(sk, 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, 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 */