LXR linux/net/core/stream.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *     SUCS NET3:
   4 *
   5 *     Generic stream handling routines. These are generic for most
   6 *     protocols. Even IP. Tonight 8-).
   7 *     This is used because TCP, LLC (others too) layer all have mostly
   8 *     identical sendmsg() and recvmsg() code.
   9 *     So we (will) share it here.
  10 *
  11 *     Authors:        Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  12 *                     (from old tcp.c code)
  13 *                     Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
  14 */
  15
  16#include <linux/module.h>
  17#include <linux/sched/signal.h>
  18#include <linux/net.h>
  19#include <linux/signal.h>
  20#include <linux/tcp.h>
  21#include <linux/wait.h>
  22#include <net/sock.h>
  23
  24/**
  25 * sk_stream_write_space - stream socket write_space callback.
  26 * @sk: socket
  27 *
  28 * FIXME: write proper description
  29 */
  30void sk_stream_write_space(struct sock *sk)
  31{
  32        struct socket *sock = sk->sk_socket;
  33        struct socket_wq *wq;
  34
  35        if (__sk_stream_is_writeable(sk, 1) && sock) {
  36                clear_bit(SOCK_NOSPACE, &sock->flags);
  37
  38                rcu_read_lock();
  39                wq = rcu_dereference(sk->sk_wq);
  40                if (skwq_has_sleeper(wq))
  41                        wake_up_interruptible_poll(&wq->wait, EPOLLOUT |
  42                                                EPOLLWRNORM | EPOLLWRBAND);
  43                if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  44                        sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
  45                rcu_read_unlock();
  46        }
  47}
  48
  49/**
  50 * sk_stream_wait_connect - Wait for a socket to get into the connected state
  51 * @sk: sock to wait on
  52 * @timeo_p: for how long to wait
  53 *
  54 * Must be called with the socket locked.
  55 */
  56int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
  57{
  58        DEFINE_WAIT_FUNC(wait, woken_wake_function);
  59        struct task_struct *tsk = current;
  60        int done;
  61
  62        do {
  63                int err = sock_error(sk);
  64                if (err)
  65                        return err;
  66                if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
  67                        return -EPIPE;
  68                if (!*timeo_p)
  69                        return -EAGAIN;
  70                if (signal_pending(tsk))
  71                        return sock_intr_errno(*timeo_p);
  72
  73                add_wait_queue(sk_sleep(sk), &wait);
  74                sk->sk_write_pending++;
  75                done = sk_wait_event(sk, timeo_p,
  76                                     !sk->sk_err &&
  77                                     !((1 << sk->sk_state) &
  78                                       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait);
  79                remove_wait_queue(sk_sleep(sk), &wait);
  80                sk->sk_write_pending--;
  81        } while (!done);
  82        return 0;
  83}
  84EXPORT_SYMBOL(sk_stream_wait_connect);
  85
  86/**
  87 * sk_stream_closing - Return 1 if we still have things to send in our buffers.
  88 * @sk: socket to verify
  89 */
  90static inline int sk_stream_closing(struct sock *sk)
  91{
  92        return (1 << sk->sk_state) &
  93               (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
  94}
  95
  96void sk_stream_wait_close(struct sock *sk, long timeout)
  97{
  98        if (timeout) {
  99                DEFINE_WAIT_FUNC(wait, woken_wake_function);
 100
 101                add_wait_queue(sk_sleep(sk), &wait);
 102
 103                do {
 104                        if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
 105                                break;
 106                } while (!signal_pending(current) && timeout);
 107
 108                remove_wait_queue(sk_sleep(sk), &wait);
 109        }
 110}
 111EXPORT_SYMBOL(sk_stream_wait_close);
 112
 113/**
 114 * sk_stream_wait_memory - Wait for more memory for a socket
 115 * @sk: socket to wait for memory
 116 * @timeo_p: for how long
 117 */
 118int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 119{
 120        int err = 0;
 121        long vm_wait = 0;
 122        long current_timeo = *timeo_p;
 123        DEFINE_WAIT_FUNC(wait, woken_wake_function);
 124
 125        if (sk_stream_memory_free(sk))
 126                current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2;
 127
 128        add_wait_queue(sk_sleep(sk), &wait);
 129
 130        while (1) {
 131                sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 132
 133                if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 134                        goto do_error;
 135                if (!*timeo_p)
 136                        goto do_eagain;
 137                if (signal_pending(current))
 138                        goto do_interrupted;
 139                sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 140                if (sk_stream_memory_free(sk) && !vm_wait)
 141                        break;
 142
 143                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 144                sk->sk_write_pending++;
 145                sk_wait_event(sk, &current_timeo, sk->sk_err ||
 146                                                  (sk->sk_shutdown & SEND_SHUTDOWN) ||
 147                                                  (sk_stream_memory_free(sk) &&
 148                                                  !vm_wait), &wait);
 149                sk->sk_write_pending--;
 150
 151                if (vm_wait) {
 152                        vm_wait -= current_timeo;
 153                        current_timeo = *timeo_p;
 154                        if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
 155                            (current_timeo -= vm_wait) < 0)
 156                                current_timeo = 0;
 157                        vm_wait = 0;
 158                }
 159                *timeo_p = current_timeo;
 160        }
 161out:
 162        remove_wait_queue(sk_sleep(sk), &wait);
 163        return err;
 164
 165do_error:
 166        err = -EPIPE;
 167        goto out;
 168do_eagain:
 169        /* Make sure that whenever EAGAIN is returned, EPOLLOUT event can
 170         * be generated later.
 171         * When TCP receives ACK packets that make room, tcp_check_space()
 172         * only calls tcp_new_space() if SOCK_NOSPACE is set.
 173         */
 174        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 175        err = -EAGAIN;
 176        goto out;
 177do_interrupted:
 178        err = sock_intr_errno(*timeo_p);
 179        goto out;
 180}
 181EXPORT_SYMBOL(sk_stream_wait_memory);
 182
 183int sk_stream_error(struct sock *sk, int flags, int err)
 184{
 185        if (err == -EPIPE)
 186                err = sock_error(sk) ? : -EPIPE;
 187        if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
 188                send_sig(SIGPIPE, current, 0);
 189        return err;
 190}
 191EXPORT_SYMBOL(sk_stream_error);
 192
 193void sk_stream_kill_queues(struct sock *sk)
 194{
 195        /* First the read buffer. */
 196        __skb_queue_purge(&sk->sk_receive_queue);
 197
 198        /* Next, the error queue. */
 199        __skb_queue_purge(&sk->sk_error_queue);
 200
 201        /* Next, the write queue. */
 202        WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
 203
 204        /* Account for returned memory. */
 205        sk_mem_reclaim(sk);
 206
 207        WARN_ON(sk->sk_wmem_queued);
 208        WARN_ON(sk->sk_forward_alloc);
 209
 210        /* It is _impossible_ for the backlog to contain anything
 211         * when we get here.  All user references to this socket
 212         * have gone away, only the net layer knows can touch it.
 213         */
 214}
 215EXPORT_SYMBOL(sk_stream_kill_queues);
 216