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  */
  28 void 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
  43 EXPORT_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  */
  52 int 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
  81 EXPORT_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  */
  87 static 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
  93 void 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
 109 EXPORT_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  */
 116 int 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         }
 159 out:
 160         finish_wait(sk->sk_sleep, &wait);
 161         return err;
 162
 163 do_error:
 164         err = -EPIPE;
 165         goto out;
 166 do_nonblock:
 167         err = -EAGAIN;
 168         goto out;
 169 do_interrupted:
 170         err = sock_intr_errno(*timeo_p);
 171         goto out;
 172 }
 173
 174 EXPORT_SYMBOL(sk_stream_wait_memory);
 175
 176 int 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
 185 EXPORT_SYMBOL(sk_stream_error);
 186
 187 void 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
 210 EXPORT_SYMBOL(sk_stream_kill_queues);