linux/net/core/stream.c
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   1/*
   2 *     SUCS NET3:
   3 *
   4 *     Generic stream handling routines. These are generic for most
   5 *     protocols. Even IP. Tonight 8-).
   6 *     This is used because TCP, LLC (others too) layer all have mostly
   7 *     identical sendmsg() and recvmsg() code.
   8 *     So we (will) share it here.
   9 *
  10 *     Authors:        Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  11 *                     (from old tcp.c code)
  12 *                     Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
  13 */
  14
  15#include <linux/module.h>
  16#include <linux/net.h>
  17#include <linux/signal.h>
  18#include <linux/tcp.h>
  19#include <linux/wait.h>
  20#include <net/sock.h>
  21
  22/**
  23 * sk_stream_write_space - stream socket write_space callback.
  24 * @sk: socket
  25 *
  26 * FIXME: write proper description
  27 */
  28void sk_stream_write_space(struct sock *sk)
  29{
  30        struct socket *sock = sk->sk_socket;
  31        struct socket_wq *wq;
  32
  33        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
  34                clear_bit(SOCK_NOSPACE, &sock->flags);
  35
  36                rcu_read_lock();
  37                wq = rcu_dereference(sk->sk_wq);
  38                if (wq_has_sleeper(wq))
  39                        wake_up_interruptible_poll(&wq->wait, POLLOUT |
  40                                                POLLWRNORM | POLLWRBAND);
  41                if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  42                        sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
  43                rcu_read_unlock();
  44        }
  45}
  46EXPORT_SYMBOL(sk_stream_write_space);
  47
  48/**
  49 * sk_stream_wait_connect - Wait for a socket to get into the connected state
  50 * @sk: sock to wait on
  51 * @timeo_p: for how long to wait
  52 *
  53 * Must be called with the socket locked.
  54 */
  55int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
  56{
  57        struct task_struct *tsk = current;
  58        DEFINE_WAIT(wait);
  59        int done;
  60
  61        do {
  62                int err = sock_error(sk);
  63                if (err)
  64                        return err;
  65                if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
  66                        return -EPIPE;
  67                if (!*timeo_p)
  68                        return -EAGAIN;
  69                if (signal_pending(tsk))
  70                        return sock_intr_errno(*timeo_p);
  71
  72                prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
  73                sk->sk_write_pending++;
  74                done = sk_wait_event(sk, timeo_p,
  75                                     !sk->sk_err &&
  76                                     !((1 << sk->sk_state) &
  77                                       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
  78                finish_wait(sk_sleep(sk), &wait);
  79                sk->sk_write_pending--;
  80        } while (!done);
  81        return 0;
  82}
  83EXPORT_SYMBOL(sk_stream_wait_connect);
  84
  85/**
  86 * sk_stream_closing - Return 1 if we still have things to send in our buffers.
  87 * @sk: socket to verify
  88 */
  89static inline int sk_stream_closing(struct sock *sk)
  90{
  91        return (1 << sk->sk_state) &
  92               (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
  93}
  94
  95void sk_stream_wait_close(struct sock *sk, long timeout)
  96{
  97        if (timeout) {
  98                DEFINE_WAIT(wait);
  99
 100                do {
 101                        prepare_to_wait(sk_sleep(sk), &wait,
 102                                        TASK_INTERRUPTIBLE);
 103                        if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
 104                                break;
 105                } while (!signal_pending(current) && timeout);
 106
 107                finish_wait(sk_sleep(sk), &wait);
 108        }
 109}
 110EXPORT_SYMBOL(sk_stream_wait_close);
 111
 112/**
 113 * sk_stream_wait_memory - Wait for more memory for a socket
 114 * @sk: socket to wait for memory
 115 * @timeo_p: for how long
 116 */
 117int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 118{
 119        int err = 0;
 120        long vm_wait = 0;
 121        long current_timeo = *timeo_p;
 122        DEFINE_WAIT(wait);
 123
 124        if (sk_stream_memory_free(sk))
 125                current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
 126
 127        while (1) {
 128                set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 129
 130                prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 131
 132                if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 133                        goto do_error;
 134                if (!*timeo_p)
 135                        goto do_nonblock;
 136                if (signal_pending(current))
 137                        goto do_interrupted;
 138                clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 139                if (sk_stream_memory_free(sk) && !vm_wait)
 140                        break;
 141
 142                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 143                sk->sk_write_pending++;
 144                sk_wait_event(sk, &current_timeo, sk->sk_err ||
 145                                                  (sk->sk_shutdown & SEND_SHUTDOWN) ||
 146                                                  (sk_stream_memory_free(sk) &&
 147                                                  !vm_wait));
 148                sk->sk_write_pending--;
 149
 150                if (vm_wait) {
 151                        vm_wait -= current_timeo;
 152                        current_timeo = *timeo_p;
 153                        if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
 154                            (current_timeo -= vm_wait) < 0)
 155                                current_timeo = 0;
 156                        vm_wait = 0;
 157                }
 158                *timeo_p = current_timeo;
 159        }
 160out:
 161        finish_wait(sk_sleep(sk), &wait);
 162        return err;
 163
 164do_error:
 165        err = -EPIPE;
 166        goto out;
 167do_nonblock:
 168        err = -EAGAIN;
 169        goto out;
 170do_interrupted:
 171        err = sock_intr_errno(*timeo_p);
 172        goto out;
 173}
 174EXPORT_SYMBOL(sk_stream_wait_memory);
 175
 176int sk_stream_error(struct sock *sk, int flags, int err)
 177{
 178        if (err == -EPIPE)
 179                err = sock_error(sk) ? : -EPIPE;
 180        if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
 181                send_sig(SIGPIPE, current, 0);
 182        return err;
 183}
 184EXPORT_SYMBOL(sk_stream_error);
 185
 186void sk_stream_kill_queues(struct sock *sk)
 187{
 188        /* First the read buffer. */
 189        __skb_queue_purge(&sk->sk_receive_queue);
 190
 191        /* Next, the error queue. */
 192        __skb_queue_purge(&sk->sk_error_queue);
 193
 194        /* Next, the write queue. */
 195        WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 196
 197        /* Account for returned memory. */
 198        sk_mem_reclaim(sk);
 199
 200        WARN_ON(sk->sk_wmem_queued);
 201        WARN_ON(sk->sk_forward_alloc);
 202
 203        /* It is _impossible_ for the backlog to contain anything
 204         * when we get here.  All user references to this socket
 205         * have gone away, only the net layer knows can touch it.
 206         */
 207}
 208EXPORT_SYMBOL(sk_stream_kill_queues);
 209
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