tcp_listen.c

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/*
 * 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(&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(&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 = SK_CAN_REUSE;
    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;
}