[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>
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 @@
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 */