linux/net/rds/tcp_listen.c
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   1/*
   2 * Copyright (c) 2006 Oracle.  All rights reserved.
   3 *
   4 * This software is available to you under a choice of one of two
   5 * licenses.  You may choose to be licensed under the terms of the GNU
   6 * General Public License (GPL) Version 2, available from the file
   7 * COPYING in the main directory of this source tree, or the
   8 * OpenIB.org BSD license below:
   9 *
  10 *     Redistribution and use in source and binary forms, with or
  11 *     without modification, are permitted provided that the following
  12 *     conditions are met:
  13 *
  14 *      - Redistributions of source code must retain the above
  15 *        copyright notice, this list of conditions and the following
  16 *        disclaimer.
  17 *
  18 *      - Redistributions in binary form must reproduce the above
  19 *        copyright notice, this list of conditions and the following
  20 *        disclaimer in the documentation and/or other materials
  21 *        provided with the distribution.
  22 *
  23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30 * SOFTWARE.
  31 *
  32 */
  33#include <linux/kernel.h>
  34#include <linux/gfp.h>
  35#include <linux/in.h>
  36#include <net/tcp.h>
  37
  38#include "rds.h"
  39#include "tcp.h"
  40
  41/*
  42 * cheesy, but simple..
  43 */
  44static void rds_tcp_accept_worker(struct work_struct *work);
  45static DECLARE_WORK(rds_tcp_listen_work, rds_tcp_accept_worker);
  46static struct socket *rds_tcp_listen_sock;
  47
  48static int rds_tcp_accept_one(struct socket *sock)
  49{
  50        struct socket *new_sock = NULL;
  51        struct rds_connection *conn;
  52        int ret;
  53        struct inet_sock *inet;
  54
  55        ret = sock_create_lite(sock->sk->sk_family, sock->sk->sk_type,
  56                               sock->sk->sk_protocol, &new_sock);
  57        if (ret)
  58                goto out;
  59
  60        new_sock->type = sock->type;
  61        new_sock->ops = sock->ops;
  62        ret = sock->ops->accept(sock, new_sock, O_NONBLOCK);
  63        if (ret < 0)
  64                goto out;
  65
  66        rds_tcp_tune(new_sock);
  67
  68        inet = inet_sk(new_sock->sk);
  69
  70        rdsdebug("accepted tcp %pI4:%u -> %pI4:%u\n",
  71                 &inet->inet_saddr, ntohs(inet->inet_sport),
  72                 &inet->inet_daddr, ntohs(inet->inet_dport));
  73
  74        conn = rds_conn_create(inet->inet_saddr, inet->inet_daddr,
  75                               &rds_tcp_transport, GFP_KERNEL);
  76        if (IS_ERR(conn)) {
  77                ret = PTR_ERR(conn);
  78                goto out;
  79        }
  80
  81        /*
  82         * see the comment above rds_queue_delayed_reconnect()
  83         */
  84        if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
  85                if (rds_conn_state(conn) == RDS_CONN_UP)
  86                        rds_tcp_stats_inc(s_tcp_listen_closed_stale);
  87                else
  88                        rds_tcp_stats_inc(s_tcp_connect_raced);
  89                rds_conn_drop(conn);
  90                ret = 0;
  91                goto out;
  92        }
  93
  94        rds_tcp_set_callbacks(new_sock, conn);
  95        rds_connect_complete(conn);
  96        new_sock = NULL;
  97        ret = 0;
  98
  99out:
 100        if (new_sock)
 101                sock_release(new_sock);
 102        return ret;
 103}
 104
 105static void rds_tcp_accept_worker(struct work_struct *work)
 106{
 107        while (rds_tcp_accept_one(rds_tcp_listen_sock) == 0)
 108                cond_resched();
 109}
 110
 111void rds_tcp_listen_data_ready(struct sock *sk, int bytes)
 112{
 113        void (*ready)(struct sock *sk, int bytes);
 114
 115        rdsdebug("listen data ready sk %p\n", sk);
 116
 117        read_lock_bh(&sk->sk_callback_lock);
 118        ready = sk->sk_user_data;
 119        if (!ready) { /* check for teardown race */
 120                ready = sk->sk_data_ready;
 121                goto out;
 122        }
 123
 124        /*
 125         * ->sk_data_ready is also called for a newly established child socket
 126         * before it has been accepted and the accepter has set up their
 127         * data_ready.. we only want to queue listen work for our listening
 128         * socket
 129         */
 130        if (sk->sk_state == TCP_LISTEN)
 131                queue_work(rds_wq, &rds_tcp_listen_work);
 132
 133out:
 134        read_unlock_bh(&sk->sk_callback_lock);
 135        ready(sk, bytes);
 136}
 137
 138int rds_tcp_listen_init(void)
 139{
 140        struct sockaddr_in sin;
 141        struct socket *sock = NULL;
 142        int ret;
 143
 144        ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
 145        if (ret < 0)
 146                goto out;
 147
 148        sock->sk->sk_reuse = SK_CAN_REUSE;
 149        rds_tcp_nonagle(sock);
 150
 151        write_lock_bh(&sock->sk->sk_callback_lock);
 152        sock->sk->sk_user_data = sock->sk->sk_data_ready;
 153        sock->sk->sk_data_ready = rds_tcp_listen_data_ready;
 154        write_unlock_bh(&sock->sk->sk_callback_lock);
 155
 156        sin.sin_family = PF_INET,
 157        sin.sin_addr.s_addr = (__force u32)htonl(INADDR_ANY);
 158        sin.sin_port = (__force u16)htons(RDS_TCP_PORT);
 159
 160        ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
 161        if (ret < 0)
 162                goto out;
 163
 164        ret = sock->ops->listen(sock, 64);
 165        if (ret < 0)
 166                goto out;
 167
 168        rds_tcp_listen_sock = sock;
 169        sock = NULL;
 170out:
 171        if (sock)
 172                sock_release(sock);
 173        return ret;
 174}
 175
 176void rds_tcp_listen_stop(void)
 177{
 178        struct socket *sock = rds_tcp_listen_sock;
 179        struct sock *sk;
 180
 181        if (!sock)
 182                return;
 183
 184        sk = sock->sk;
 185
 186        /* serialize with and prevent further callbacks */
 187        lock_sock(sk);
 188        write_lock_bh(&sk->sk_callback_lock);
 189        if (sk->sk_user_data) {
 190                sk->sk_data_ready = sk->sk_user_data;
 191                sk->sk_user_data = NULL;
 192        }
 193        write_unlock_bh(&sk->sk_callback_lock);
 194        release_sock(sk);
 195
 196        /* wait for accepts to stop and close the socket */
 197        flush_workqueue(rds_wq);
 198        sock_release(sock);
 199        rds_tcp_listen_sock = NULL;
 200}
 201
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