/*
 * Copyright (c) 2006 Oracle.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/in.h>
#include <net/tcp.h>

#include "rds.h"
#include "tcp.h"

/*
 * cheesy, but simple..
 */
static void rds_tcp_accept_worker(struct work_struct *work);
static DECLARE_WORK(rds_tcp_listen_work, rds_tcp_accept_worker);
static struct socket *rds_tcp_listen_sock;

static int rds_tcp_accept_one(struct socket *sock)
{
        struct socket *new_sock = NULL;
        struct rds_connection *conn;
        int ret;
        struct inet_sock *inet;

        ret = sock_create_lite(sock->sk->sk_family, sock->sk->sk_type,
                               sock->sk->sk_protocol, &new_sock);
        if (ret)
                goto out;

        new_sock->type = sock->type;
        new_sock->ops = sock->ops;
        ret = sock->ops->accept(sock, new_sock, O_NONBLOCK);
        if (ret < 0)
                goto out;

        rds_tcp_tune(new_sock);

        inet = inet_sk(new_sock->sk);

        rdsdebug("accepted tcp %pI4:%u -> %pI4:%u\n",
                 &inet->inet_saddr, ntohs(inet->inet_sport),
                 &inet->inet_daddr, ntohs(inet->inet_dport));

        conn = rds_conn_create(inet->inet_saddr, inet->inet_daddr,
                               &rds_tcp_transport, GFP_KERNEL);
        if (IS_ERR(conn)) {
                ret = PTR_ERR(conn);
                goto out;
        }

        /*
         * see the comment above rds_queue_delayed_reconnect()
         */
        if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
                if (rds_conn_state(conn) == RDS_CONN_UP)
                        rds_tcp_stats_inc(s_tcp_listen_closed_stale);
                else
                        rds_tcp_stats_inc(s_tcp_connect_raced);
                rds_conn_drop(conn);
                ret = 0;
                goto out;
        }

        rds_tcp_set_callbacks(new_sock, conn);
        rds_connect_complete(conn);
        new_sock = NULL;
        ret = 0;

out:
        if (new_sock)
                sock_release(new_sock);
        return ret;
}

static void rds_tcp_accept_worker(struct work_struct *work)
{
        while (rds_tcp_accept_one(rds_tcp_listen_sock) == 0)
                cond_resched();
}

void rds_tcp_listen_data_ready(struct sock *sk, int bytes)
{
        void (*ready)(struct sock *sk, int bytes);

        rdsdebug("listen data ready sk %p\n", sk);

        read_lock_bh(&sk->sk_callback_lock);
        ready = sk->sk_user_data;
        if (!ready) { /* check for teardown race */
                ready = sk->sk_data_ready;
                goto out;
        }

        /*
         * ->sk_data_ready is also called for a newly established child socket
         * before it has been accepted and the accepter has set up their
         * data_ready.. we only want to queue listen work for our listening
         * socket
         */
        if (sk->sk_state == TCP_LISTEN)
                queue_work(rds_wq, &rds_tcp_listen_work);

out:
        read_unlock_bh(&sk->sk_callback_lock);
        ready(sk, bytes);
}

int rds_tcp_listen_init(void)
{
        struct sockaddr_in sin;
        struct socket *sock = NULL;
        int ret;

        ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
        if (ret < 0)
                goto out;

        sock->sk->sk_reuse = 1;
        rds_tcp_nonagle(sock);

        write_lock_bh(&sock->sk->sk_callback_lock);
        sock->sk->sk_user_data = sock->sk->sk_data_ready;
        sock->sk->sk_data_ready = rds_tcp_listen_data_ready;
        write_unlock_bh(&sock->sk->sk_callback_lock);

        sin.sin_family = PF_INET,
        sin.sin_addr.s_addr = (__force u32)htonl(INADDR_ANY);
        sin.sin_port = (__force u16)htons(RDS_TCP_PORT);

        ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
        if (ret < 0)
                goto out;

        ret = sock->ops->listen(sock, 64);
        if (ret < 0)
                goto out;

        rds_tcp_listen_sock = sock;
        sock = NULL;
out:
        if (sock)
                sock_release(sock);
        return ret;
}

void rds_tcp_listen_stop(void)
{
        struct socket *sock = rds_tcp_listen_sock;
        struct sock *sk;

        if (!sock)
                return;

        sk = sock->sk;

        /* serialize with and prevent further callbacks */
        lock_sock(sk);
        write_lock_bh(&sk->sk_callback_lock);
        if (sk->sk_user_data) {
                sk->sk_data_ready = sk->sk_user_data;
                sk->sk_user_data = NULL;
        }
        write_unlock_bh(&sk->sk_callback_lock);
        release_sock(sk);

        /* wait for accepts to stop and close the socket */
        flush_workqueue(rds_wq);
        sock_release(sock);
        rds_tcp_listen_sock = NULL;
}