stream.c

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/*
 *     SUCS NET3:
 *
 *     Generic stream handling routines. These are generic for most
 *     protocols. Even IP. Tonight 8-).
 *     This is used because TCP, LLC (others too) layer all have mostly
 *     identical sendmsg() and recvmsg() code.
 *     So we (will) share it here.
 *
 *     Authors:        Arnaldo Carvalho de Melo <[email protected]>
 *                     (from old tcp.c code)
 *                     Alan Cox <[email protected]> (Borrowed comments 8-))
 */

#include <linux/module.h>
#include <linux/net.h>
#include <linux/signal.h>
#include <linux/tcp.h>
#include <linux/wait.h>
#include <net/sock.h>

void sk_stream_write_space(struct sock *sk)
{
    struct socket *sock = sk->sk_socket;
    struct socket_wq *wq;

    if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
        clear_bit(SOCK_NOSPACE, &sock->flags);

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (wq_has_sleeper(wq))
            wake_up_interruptible_poll(&wq->wait, POLLOUT |
                        POLLWRNORM | POLLWRBAND);
        if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
            sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
        rcu_read_unlock();
    }
}
EXPORT_SYMBOL(sk_stream_write_space);

int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
{
    struct task_struct *tsk = current;
    DEFINE_WAIT(wait);
    int done;

    do {
        int err = sock_error(sk);
        if (err)
            return err;
        if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
            return -EPIPE;
        if (!*timeo_p)
            return -EAGAIN;
        if (signal_pending(tsk))
            return sock_intr_errno(*timeo_p);

        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
        sk->sk_write_pending++;
        done = sk_wait_event(sk, timeo_p,
                     !sk->sk_err &&
                     !((1 << sk->sk_state) &
                       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
        finish_wait(sk_sleep(sk), &wait);
        sk->sk_write_pending--;
    } while (!done);
    return 0;
}
EXPORT_SYMBOL(sk_stream_wait_connect);

static inline int sk_stream_closing(struct sock *sk)
{
    return (1 << sk->sk_state) &
           (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
}

void sk_stream_wait_close(struct sock *sk, long timeout)
{
    if (timeout) {
        DEFINE_WAIT(wait);

        do {
            prepare_to_wait(sk_sleep(sk), &wait,
                    TASK_INTERRUPTIBLE);
            if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
                break;
        } while (!signal_pending(current) && timeout);

        finish_wait(sk_sleep(sk), &wait);
    }
}
EXPORT_SYMBOL(sk_stream_wait_close);

int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
{
    int err = 0;
    long vm_wait = 0;
    long current_timeo = *timeo_p;
    DEFINE_WAIT(wait);

    if (sk_stream_memory_free(sk))
        current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;

    while (1) {
        set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);

        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
            goto do_error;
        if (!*timeo_p)
            goto do_nonblock;
        if (signal_pending(current))
            goto do_interrupted;
        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
        if (sk_stream_memory_free(sk) && !vm_wait)
            break;

        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
        sk->sk_write_pending++;
        sk_wait_event(sk, &current_timeo, sk->sk_err ||
                          (sk->sk_shutdown & SEND_SHUTDOWN) ||
                          (sk_stream_memory_free(sk) &&
                          !vm_wait));
        sk->sk_write_pending--;

        if (vm_wait) {
            vm_wait -= current_timeo;
            current_timeo = *timeo_p;
            if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
                (current_timeo -= vm_wait) < 0)
                current_timeo = 0;
            vm_wait = 0;
        }
        *timeo_p = current_timeo;
    }
out:
    finish_wait(sk_sleep(sk), &wait);
    return err;

do_error:
    err = -EPIPE;
    goto out;
do_nonblock:
    err = -EAGAIN;
    goto out;
do_interrupted:
    err = sock_intr_errno(*timeo_p);
    goto out;
}
EXPORT_SYMBOL(sk_stream_wait_memory);

int sk_stream_error(struct sock *sk, int flags, int err)
{
    if (err == -EPIPE)
        err = sock_error(sk) ? : -EPIPE;
    if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
        send_sig(SIGPIPE, current, 0);
    return err;
}
EXPORT_SYMBOL(sk_stream_error);

void sk_stream_kill_queues(struct sock *sk)
{
    /* First the read buffer. */
    __skb_queue_purge(&sk->sk_receive_queue);

    /* Next, the error queue. */
    __skb_queue_purge(&sk->sk_error_queue);

    /* Next, the write queue. */
    WARN_ON(!skb_queue_empty(&sk->sk_write_queue));

    /* Account for returned memory. */
    sk_mem_reclaim(sk);

    WARN_ON(sk->sk_wmem_queued);
    WARN_ON(sk->sk_forward_alloc);

    /* It is _impossible_ for the backlog to contain anything
     * when we get here.  All user references to this socket
     * have gone away, only the net layer knows can touch it.
     */
}
EXPORT_SYMBOL(sk_stream_kill_queues);