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@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 */
  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(sk->sk_sleep);
  37                if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  38                        sock_wake_async(sock, 2, POLL_OUT);
  39        }
  40}
  41
  42EXPORT_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 */
  51int 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
  80EXPORT_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 */
  86static 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
  92void 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
 108EXPORT_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 */
 115int 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        }
 158out:
 159        finish_wait(sk->sk_sleep, &wait);
 160        return err;
 161
 162do_error:
 163        err = -EPIPE;
 164        goto out;
 165do_nonblock:
 166        err = -EAGAIN;
 167        goto out;
 168do_interrupted:
 169        err = sock_intr_errno(*timeo_p);
 170        goto out;
 171}
 172
 173EXPORT_SYMBOL(sk_stream_wait_memory);
 174
 175void sk_stream_rfree(struct sk_buff *skb)
 176{
 177        struct sock *sk = skb->sk;
 178
 179        skb_truesize_check(skb);
 180        atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
 181        sk->sk_forward_alloc += skb->truesize;
 182}
 183
 184EXPORT_SYMBOL(sk_stream_rfree);
 185
 186int sk_stream_error(struct sock *sk, int flags, int err)
 187{
 188        if (err == -EPIPE)
 189                err = sock_error(sk) ? : -EPIPE;
 190        if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
 191                send_sig(SIGPIPE, current, 0);
 192        return err;
 193}
 194
 195EXPORT_SYMBOL(sk_stream_error);
 196
 197void __sk_stream_mem_reclaim(struct sock *sk)
 198{
 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
 208EXPORT_SYMBOL(__sk_stream_mem_reclaim);
 209
 210int sk_stream_mem_schedule(struct sock *sk, int size, int kind)
 211{
 212        int amt = sk_stream_pages(size);
 213
 214        sk->sk_forward_alloc += amt * SK_STREAM_MEM_QUANTUM;
 215        atomic_add(amt, sk->sk_prot->memory_allocated);
 216
 217        /* Under limit. */
 218        if (atomic_read(sk->sk_prot->memory_allocated) < sk->sk_prot->sysctl_mem[0]) {
 219                if (*sk->sk_prot->memory_pressure)
 220                        *sk->sk_prot->memory_pressure = 0;
 221                return 1;
 222        }
 223
 224        /* Over hard limit. */
 225        if (atomic_read(sk->sk_prot->memory_allocated) > sk->sk_prot->sysctl_mem[2]) {
 226                sk->sk_prot->enter_memory_pressure();
 227                goto suppress_allocation;
 228        }
 229
 230        /* Under pressure. */
 231        if (atomic_read(sk->sk_prot->memory_allocated) > sk->sk_prot->sysctl_mem[1])
 232                sk->sk_prot->enter_memory_pressure();
 233
 234        if (kind) {
 235                if (atomic_read(&sk->sk_rmem_alloc) < sk->sk_prot->sysctl_rmem[0])
 236                        return 1;
 237        } else if (sk->sk_wmem_queued < sk->sk_prot->sysctl_wmem[0])
 238                return 1;
 239
 240        if (!*sk->sk_prot->memory_pressure ||
 241            sk->sk_prot->sysctl_mem[2] > atomic_read(sk->sk_prot->sockets_allocated) *
 242                                sk_stream_pages(sk->sk_wmem_queued +
 243                                                atomic_read(&sk->sk_rmem_alloc) +
 244                                                sk->sk_forward_alloc))
 245                return 1;
 246
 247suppress_allocation:
 248
 249        if (!kind) {
 250                sk_stream_moderate_sndbuf(sk);
 251
 252                /* Fail only if socket is _under_ its sndbuf.
 253                 * In this case we cannot block, so that we have to fail.
 254                 */
 255                if (sk->sk_wmem_queued + size >= sk->sk_sndbuf)
 256                        return 1;
 257        }
 258
 259        /* Alas. Undo changes. */
 260        sk->sk_forward_alloc -= amt * SK_STREAM_MEM_QUANTUM;
 261        atomic_sub(amt, sk->sk_prot->memory_allocated);
 262        return 0;
 263}
 264
 265EXPORT_SYMBOL(sk_stream_mem_schedule);
 266
 267void sk_stream_kill_queues(struct sock *sk)
 268{
 269        /* First the read buffer. */
 270        __skb_queue_purge(&sk->sk_receive_queue);
 271
 272        /* Next, the error queue. */
 273        __skb_queue_purge(&sk->sk_error_queue);
 274
 275        /* Next, the write queue. */
 276        BUG_TRAP(skb_queue_empty(&sk->sk_write_queue));
 277
 278        /* Account for returned memory. */
 279        sk_stream_mem_reclaim(sk);
 280
 281        BUG_TRAP(!sk->sk_wmem_queued);
 282        BUG_TRAP(!sk->sk_forward_alloc);
 283
 284        /* It is _impossible_ for the backlog to contain anything
 285         * when we get here.  All user references to this socket
 286         * have gone away, only the net layer knows can touch it.
 287         */
 288}
 289
 290EXPORT_SYMBOL(sk_stream_kill_queues);
 291