[INET]: Move the TCP hashtable functions/structs to inet_hashtables.[ch]

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 122 insertions, 0 deletions

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index c4c9e39..3a6c11c 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -14,8 +14,107 @@
 #ifndef _INET_HASHTABLES_H
 #define _INET_HASHTABLES_H
 
+#include <linux/ip.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
 #include <linux/types.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;
+};
+
 static inline int inet_ehashfn(const __u32 laddr, const __u16 lport,
 			       const __u32 faddr, const __u16 fport,
 			       const int ehash_size)
@@ -37,4 +136,27 @@ static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size)
 	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);
+}
+
+/* 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);
+}
+
 #endif /* _INET_HASHTABLES_H */