LXR linux/net/core/stream.c

   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
  32        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
  33                clear_bit(SOCK_NOSPACE, &sock->flags);
  34
  35                if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
  36                        wake_up_interruptible_poll(sk->sk_sleep, POLLOUT |
  37                                                POLLWRNORM | POLLWRBAND);
  38                if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  39                        sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
  40        }
  41}
  42
  43EXPORT_SYMBOL(sk_stream_write_space);
  44
  45/**
  46 * sk_stream_wait_connect - Wait for a socket to get into the connected state
  47 * @sk: sock to wait on
  48 * @timeo_p: for how long to wait
  49 *
  50 * Must be called with the socket locked.
  51 */
  52int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
  53{
  54        struct task_struct *tsk = current;
  55        DEFINE_WAIT(wait);
  56        int done;
  57
  58        do {
  59                int err = sock_error(sk);
  60                if (err)
  61                        return err;
  62                if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
  63                        return -EPIPE;
  64                if (!*timeo_p)
  65                        return -EAGAIN;
  66                if (signal_pending(tsk))
  67                        return sock_intr_errno(*timeo_p);
  68
  69                prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
  70                sk->sk_write_pending++;
  71                done = sk_wait_event(sk, timeo_p,
  72                                     !sk->sk_err &&
  73                                     !((1 << sk->sk_state) &
  74                                       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
  75                finish_wait(sk->sk_sleep, &wait);
  76                sk->sk_write_pending--;
  77        } while (!done);
  78        return 0;
  79}
  80
  81EXPORT_SYMBOL(sk_stream_wait_connect);
  82
  83/**
  84 * sk_stream_closing - Return 1 if we still have things to send in our buffers.
  85 * @sk: socket to verify
  86 */
  87static inline int sk_stream_closing(struct sock *sk)
  88{
  89        return (1 << sk->sk_state) &
  90               (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
  91}
  92
  93void sk_stream_wait_close(struct sock *sk, long timeout)
  94{
  95        if (timeout) {
  96                DEFINE_WAIT(wait);
  97
  98                do {
  99                        prepare_to_wait(sk->sk_sleep, &wait,
 100                                        TASK_INTERRUPTIBLE);
 101                        if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
 102                                break;
 103                } while (!signal_pending(current) && timeout);
 104
 105                finish_wait(sk->sk_sleep, &wait);
 106        }
 107}
 108
 109EXPORT_SYMBOL(sk_stream_wait_close);
 110
 111/**
 112 * sk_stream_wait_memory - Wait for more memory for a socket
 113 * @sk: socket to wait for memory
 114 * @timeo_p: for how long
 115 */
 116int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 117{
 118        int err = 0;
 119        long vm_wait = 0;
 120        long current_timeo = *timeo_p;
 121        DEFINE_WAIT(wait);
 122
 123        if (sk_stream_memory_free(sk))
 124                current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
 125
 126        while (1) {
 127                set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 128
 129                prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 130
 131                if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 132                        goto do_error;
 133                if (!*timeo_p)
 134                        goto do_nonblock;
 135                if (signal_pending(current))
 136                        goto do_interrupted;
 137                clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 138                if (sk_stream_memory_free(sk) && !vm_wait)
 139                        break;
 140
 141                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 142                sk->sk_write_pending++;
 143                sk_wait_event(sk, &current_timeo, !sk->sk_err &&
 144                                                  !(sk->sk_shutdown & SEND_SHUTDOWN) &&
 145                                                  sk_stream_memory_free(sk) &&
 146                                                  vm_wait);
 147                sk->sk_write_pending--;
 148
 149                if (vm_wait) {
 150                        vm_wait -= current_timeo;
 151                        current_timeo = *timeo_p;
 152                        if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
 153                            (current_timeo -= vm_wait) < 0)
 154                                current_timeo = 0;
 155                        vm_wait = 0;
 156                }
 157                *timeo_p = current_timeo;
 158        }
 159out:
 160        finish_wait(sk->sk_sleep, &wait);
 161        return err;
 162
 163do_error:
 164        err = -EPIPE;
 165        goto out;
 166do_nonblock:
 167        err = -EAGAIN;
 168        goto out;
 169do_interrupted:
 170        err = sock_intr_errno(*timeo_p);
 171        goto out;
 172}
 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}
 184
 185EXPORT_SYMBOL(sk_stream_error);
 186
 187void sk_stream_kill_queues(struct sock *sk)
 188{
 189        /* First the read buffer. */
 190        __skb_queue_purge(&sk->sk_receive_queue);
 191
 192        /* Next, the error queue. */
 193        __skb_queue_purge(&sk->sk_error_queue);
 194
 195        /* Next, the write queue. */
 196        WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 197
 198        /* Account for returned memory. */
 199        sk_mem_reclaim(sk);
 200
 201        WARN_ON(sk->sk_wmem_queued);
 202        WARN_ON(sk->sk_forward_alloc);
 203
 204        /* It is _impossible_ for the backlog to contain anything
 205         * when we get here.  All user references to this socket
 206         * have gone away, only the net layer knows can touch it.
 207         */
 208}
 209
 210EXPORT_SYMBOL(sk_stream_kill_queues);
 211