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