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@redhat.com> (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(sk->sk_sleep);
  37                 if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  38                         sock_wake_async(sock, 2, POLL_OUT);
  39         }
  40 }
  41
  42 EXPORT_SYMBOL(sk_stream_write_space);
  43
  44 /**
  45  * sk_stream_wait_connect - Wait for a socket to get into the connected state
  46  * @sk: sock to wait on
  47  * @timeo_p: for how long to wait
  48  *
  49  * Must be called with the socket locked.
  50  */
  51 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
  52 {
  53         struct task_struct *tsk = current;
  54         DEFINE_WAIT(wait);
  55         int done;
  56
  57         do {
  58                 int err = sock_error(sk);
  59                 if (err)
  60                         return err;
  61                 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
  62                         return -EPIPE;
  63                 if (!*timeo_p)
  64                         return -EAGAIN;
  65                 if (signal_pending(tsk))
  66                         return sock_intr_errno(*timeo_p);
  67
  68                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
  69                 sk->sk_write_pending++;
  70                 done = sk_wait_event(sk, timeo_p,
  71                                      !sk->sk_err &&
  72                                      !((1 << sk->sk_state) &
  73                                        ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
  74                 finish_wait(sk->sk_sleep, &wait);
  75                 sk->sk_write_pending--;
  76         } while (!done);
  77         return 0;
  78 }
  79
  80 EXPORT_SYMBOL(sk_stream_wait_connect);
  81
  82 /**
  83  * sk_stream_closing - Return 1 if we still have things to send in our buffers.
  84  * @sk: socket to verify
  85  */
  86 static inline int sk_stream_closing(struct sock *sk)
  87 {
  88         return (1 << sk->sk_state) &
  89                (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
  90 }
  91
  92 void sk_stream_wait_close(struct sock *sk, long timeout)
  93 {
  94         if (timeout) {
  95                 DEFINE_WAIT(wait);
  96
  97                 do {
  98                         prepare_to_wait(sk->sk_sleep, &wait,
  99                                         TASK_INTERRUPTIBLE);
 100                         if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
 101                                 break;
 102                 } while (!signal_pending(current) && timeout);
 103
 104                 finish_wait(sk->sk_sleep, &wait);
 105         }
 106 }
 107
 108 EXPORT_SYMBOL(sk_stream_wait_close);
 109
 110 /**
 111  * sk_stream_wait_memory - Wait for more memory for a socket
 112  * @sk: socket to wait for memory
 113  * @timeo_p: for how long
 114  */
 115 int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 116 {
 117         int err = 0;
 118         long vm_wait = 0;
 119         long current_timeo = *timeo_p;
 120         DEFINE_WAIT(wait);
 121
 122         if (sk_stream_memory_free(sk))
 123                 current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
 124
 125         while (1) {
 126                 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 127
 128                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 129
 130                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 131                         goto do_error;
 132                 if (!*timeo_p)
 133                         goto do_nonblock;
 134                 if (signal_pending(current))
 135                         goto do_interrupted;
 136                 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 137                 if (sk_stream_memory_free(sk) && !vm_wait)
 138                         break;
 139
 140                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 141                 sk->sk_write_pending++;
 142                 sk_wait_event(sk, &current_timeo, !sk->sk_err &&
 143                                                   !(sk->sk_shutdown & SEND_SHUTDOWN) &&
 144                                                   sk_stream_memory_free(sk) &&
 145                                                   vm_wait);
 146                 sk->sk_write_pending--;
 147
 148                 if (vm_wait) {
 149                         vm_wait -= current_timeo;
 150                         current_timeo = *timeo_p;
 151                         if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
 152                             (current_timeo -= vm_wait) < 0)
 153                                 current_timeo = 0;
 154                         vm_wait = 0;
 155                 }
 156                 *timeo_p = current_timeo;
 157         }
 158 out:
 159         finish_wait(sk->sk_sleep, &wait);
 160         return err;
 161
 162 do_error:
 163         err = -EPIPE;
 164         goto out;
 165 do_nonblock:
 166         err = -EAGAIN;
 167         goto out;
 168 do_interrupted:
 169         err = sock_intr_errno(*timeo_p);
 170         goto out;
 171 }
 172
 173 EXPORT_SYMBOL(sk_stream_wait_memory);
 174
 175 void sk_stream_rfree(struct sk_buff *skb)
 176 {
 177         struct sock *sk = skb->sk;
 178
 179         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
 180         sk->sk_forward_alloc += skb->truesize;
 181 }
 182
 183 EXPORT_SYMBOL(sk_stream_rfree);
 184
 185 int sk_stream_error(struct sock *sk, int flags, int err)
 186 {
 187         if (err == -EPIPE)
 188                 err = sock_error(sk) ? : -EPIPE;
 189         if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
 190                 send_sig(SIGPIPE, current, 0);
 191         return err;
 192 }
 193
 194 EXPORT_SYMBOL(sk_stream_error);
 195
 196 void __sk_stream_mem_reclaim(struct sock *sk)
 197 {
 198         if (sk->sk_forward_alloc >= SK_STREAM_MEM_QUANTUM) {
 199                 atomic_sub(sk->sk_forward_alloc / SK_STREAM_MEM_QUANTUM,
 200                            sk->sk_prot->memory_allocated);
 201                 sk->sk_forward_alloc &= SK_STREAM_MEM_QUANTUM - 1;
 202                 if (*sk->sk_prot->memory_pressure &&
 203                     (atomic_read(sk->sk_prot->memory_allocated) <
 204                      sk->sk_prot->sysctl_mem[0]))
 205                         *sk->sk_prot->memory_pressure = 0;
 206         }
 207 }
 208
 209 EXPORT_SYMBOL(__sk_stream_mem_reclaim);
 210
 211 int sk_stream_mem_schedule(struct sock *sk, int size, int kind)
 212 {
 213         int amt = sk_stream_pages(size);
 214
 215         sk->sk_forward_alloc += amt * SK_STREAM_MEM_QUANTUM;
 216         atomic_add(amt, sk->sk_prot->memory_allocated);
 217
 218         /* Under limit. */
 219         if (atomic_read(sk->sk_prot->memory_allocated) < sk->sk_prot->sysctl_mem[0]) {
 220                 if (*sk->sk_prot->memory_pressure)
 221                         *sk->sk_prot->memory_pressure = 0;
 222                 return 1;
 223         }
 224
 225         /* Over hard limit. */
 226         if (atomic_read(sk->sk_prot->memory_allocated) > sk->sk_prot->sysctl_mem[2]) {
 227                 sk->sk_prot->enter_memory_pressure();
 228                 goto suppress_allocation;
 229         }
 230
 231         /* Under pressure. */
 232         if (atomic_read(sk->sk_prot->memory_allocated) > sk->sk_prot->sysctl_mem[1])
 233                 sk->sk_prot->enter_memory_pressure();
 234
 235         if (kind) {
 236                 if (atomic_read(&sk->sk_rmem_alloc) < sk->sk_prot->sysctl_rmem[0])
 237                         return 1;
 238         } else if (sk->sk_wmem_queued < sk->sk_prot->sysctl_wmem[0])
 239                 return 1;
 240
 241         if (!*sk->sk_prot->memory_pressure ||
 242             sk->sk_prot->sysctl_mem[2] > atomic_read(sk->sk_prot->sockets_allocated) *
 243                                 sk_stream_pages(sk->sk_wmem_queued +
 244                                                 atomic_read(&sk->sk_rmem_alloc) +
 245                                                 sk->sk_forward_alloc))
 246                 return 1;
 247
 248 suppress_allocation:
 249
 250         if (!kind) {
 251                 sk_stream_moderate_sndbuf(sk);
 252
 253                 /* Fail only if socket is _under_ its sndbuf.
 254                  * In this case we cannot block, so that we have to fail.
 255                  */
 256                 if (sk->sk_wmem_queued + size >= sk->sk_sndbuf)
 257                         return 1;
 258         }
 259
 260         /* Alas. Undo changes. */
 261         sk->sk_forward_alloc -= amt * SK_STREAM_MEM_QUANTUM;
 262         atomic_sub(amt, sk->sk_prot->memory_allocated);
 263         return 0;
 264 }
 265
 266 EXPORT_SYMBOL(sk_stream_mem_schedule);
 267
 268 void sk_stream_kill_queues(struct sock *sk)
 269 {
 270         /* First the read buffer. */
 271         __skb_queue_purge(&sk->sk_receive_queue);
 272
 273         /* Next, the error queue. */
 274         __skb_queue_purge(&sk->sk_error_queue);
 275
 276         /* Next, the write queue. */
 277         BUG_TRAP(skb_queue_empty(&sk->sk_write_queue));
 278
 279         /* Account for returned memory. */
 280         sk_stream_mem_reclaim(sk);
 281
 282         BUG_TRAP(!sk->sk_wmem_queued);
 283         BUG_TRAP(!sk->sk_forward_alloc);
 284
 285         /* It is _impossible_ for the backlog to contain anything
 286          * when we get here.  All user references to this socket
 287          * have gone away, only the net layer knows can touch it.
 288          */
 289 }
 290
 291 EXPORT_SYMBOL(sk_stream_kill_queues);