release/src-rt-6.x.4708/linux/linux-2.6.36/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 void sk_stream_write_space(struct sock *sk)
  23 {
  24         struct socket *sock = sk->sk_socket;
  25         struct socket_wq *wq;
  26
  27         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
  28                 clear_bit(SOCK_NOSPACE, &sock->flags);
  29
  30                 rcu_read_lock();
  31                 wq = rcu_dereference(sk->sk_wq);
  32                 if (wq_has_sleeper(wq))
  33                         wake_up_interruptible_poll(&wq->wait, POLLOUT |
  34                                                 POLLWRNORM | POLLWRBAND);
  35                 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  36                         sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
  37                 rcu_read_unlock();
  38         }
  39 }
  40 EXPORT_SYMBOL(sk_stream_write_space);
  41
  42 /**
  43  * sk_stream_wait_connect - Wait for a socket to get into the connected state
  44  * @sk: sock to wait on
  45  * @timeo_p: for how long to wait
  46  *
  47  * Must be called with the socket locked.
  48  */
  49 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
  50 {
  51         struct task_struct *tsk = current;
  52         DEFINE_WAIT(wait);
  53         int done;
  54
  55         do {
  56                 int err = sock_error(sk);
  57                 if (err)
  58                         return err;
  59                 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
  60                         return -EPIPE;
  61                 if (!*timeo_p)
  62                         return -EAGAIN;
  63                 if (signal_pending(tsk))
  64                         return sock_intr_errno(*timeo_p);
  65
  66                 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
  67                 sk->sk_write_pending++;
  68                 done = sk_wait_event(sk, timeo_p,
  69                                      !sk->sk_err &&
  70                                      !((1 << sk->sk_state) &
  71                                        ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
  72                 finish_wait(sk_sleep(sk), &wait);
  73                 sk->sk_write_pending--;
  74         } while (!done);
  75         return 0;
  76 }
  77 EXPORT_SYMBOL(sk_stream_wait_connect);
  78
  79 /**
  80  * sk_stream_closing - Return 1 if we still have things to send in our buffers.
  81  * @sk: socket to verify
  82  */
  83 static inline int sk_stream_closing(struct sock *sk)
  84 {
  85         return (1 << sk->sk_state) &
  86                (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
  87 }
  88
  89 void sk_stream_wait_close(struct sock *sk, long timeout)
  90 {
  91         if (timeout) {
  92                 DEFINE_WAIT(wait);
  93
  94                 do {
  95                         prepare_to_wait(sk_sleep(sk), &wait,
  96                                         TASK_INTERRUPTIBLE);
  97                         if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
  98                                 break;
  99                 } while (!signal_pending(current) && timeout);
 100
 101                 finish_wait(sk_sleep(sk), &wait);
 102         }
 103 }
 104 EXPORT_SYMBOL(sk_stream_wait_close);
 105
 106 /**
 107  * sk_stream_wait_memory - Wait for more memory for a socket
 108  * @sk: socket to wait for memory
 109  * @timeo_p: for how long
 110  */
 111 int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 112 {
 113         int err = 0;
 114         long vm_wait = 0;
 115         long current_timeo = *timeo_p;
 116         DEFINE_WAIT(wait);
 117
 118         if (sk_stream_memory_free(sk))
 119                 current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
 120
 121         while (1) {
 122                 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 123
 124                 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 125
 126                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 127                         goto do_error;
 128                 if (!*timeo_p)
 129                         goto do_nonblock;
 130                 if (signal_pending(current))
 131                         goto do_interrupted;
 132                 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 133                 if (sk_stream_memory_free(sk) && !vm_wait)
 134                         break;
 135
 136                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 137                 sk->sk_write_pending++;
 138                 sk_wait_event(sk, &current_timeo, sk->sk_err ||
 139                                                   (sk->sk_shutdown & SEND_SHUTDOWN) ||
 140                                                   (sk_stream_memory_free(sk) &&
 141                                                   !vm_wait));
 142                 sk->sk_write_pending--;
 143
 144                 if (vm_wait) {
 145                         vm_wait -= current_timeo;
 146                         current_timeo = *timeo_p;
 147                         if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
 148                             (current_timeo -= vm_wait) < 0)
 149                                 current_timeo = 0;
 150                         vm_wait = 0;
 151                 }
 152                 *timeo_p = current_timeo;
 153         }
 154 out:
 155         finish_wait(sk_sleep(sk), &wait);
 156         return err;
 157
 158 do_error:
 159         err = -EPIPE;
 160         goto out;
 161 do_nonblock:
 162         err = -EAGAIN;
 163         goto out;
 164 do_interrupted:
 165         err = sock_intr_errno(*timeo_p);
 166         goto out;
 167 }
 168 EXPORT_SYMBOL(sk_stream_wait_memory);
 169
 170 int sk_stream_error(struct sock *sk, int flags, int err)
 171 {
 172         if (err == -EPIPE)
 173                 err = sock_error(sk) ? : -EPIPE;
 174         if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
 175                 send_sig(SIGPIPE, current, 0);
 176         return err;
 177 }
 178 EXPORT_SYMBOL(sk_stream_error);
 179
 180 void sk_stream_kill_queues(struct sock *sk)
 181 {
 182         /* First the read buffer. */
 183         __skb_queue_purge(&sk->sk_receive_queue);
 184
 185         /* Next, the error queue. */
 186         __skb_queue_purge(&sk->sk_error_queue);
 187
 188         /* Next, the write queue. */
 189         WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 190
 191         /* Account for returned memory. */
 192         sk_mem_reclaim(sk);
 193
 194         WARN_ON(sk->sk_wmem_queued);
 195         WARN_ON(sk->sk_forward_alloc);
 196
 197         /* It is _impossible_ for the backlog to contain anything
 198          * when we get here.  All user references to this socket
 199          * have gone away, only the net layer knows can touch it.
 200          */
 201 }
 202 EXPORT_SYMBOL(sk_stream_kill_queues);