| 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 | struct socket_wq *wq; |
| 32 | |
| 33 | if (sk_stream_is_writeable(sk) && sock) { |
| 34 | clear_bit(SOCK_NOSPACE, &sock->flags); |
| 35 | |
| 36 | rcu_read_lock(); |
| 37 | wq = rcu_dereference(sk->sk_wq); |
| 38 | if (skwq_has_sleeper(wq)) |
| 39 | wake_up_interruptible_poll(&wq->wait, POLLOUT | |
| 40 | POLLWRNORM | POLLWRBAND); |
| 41 | if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN)) |
| 42 | sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT); |
| 43 | rcu_read_unlock(); |
| 44 | } |
| 45 | } |
| 46 | EXPORT_SYMBOL(sk_stream_write_space); |
| 47 | |
| 48 | /** |
| 49 | * sk_stream_wait_connect - Wait for a socket to get into the connected state |
| 50 | * @sk: sock to wait on |
| 51 | * @timeo_p: for how long to wait |
| 52 | * |
| 53 | * Must be called with the socket locked. |
| 54 | */ |
| 55 | int sk_stream_wait_connect(struct sock *sk, long *timeo_p) |
| 56 | { |
| 57 | struct task_struct *tsk = current; |
| 58 | DEFINE_WAIT(wait); |
| 59 | int done; |
| 60 | |
| 61 | do { |
| 62 | int err = sock_error(sk); |
| 63 | if (err) |
| 64 | return err; |
| 65 | if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) |
| 66 | return -EPIPE; |
| 67 | if (!*timeo_p) |
| 68 | return -EAGAIN; |
| 69 | if (signal_pending(tsk)) |
| 70 | return sock_intr_errno(*timeo_p); |
| 71 | |
| 72 | prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); |
| 73 | sk->sk_write_pending++; |
| 74 | done = sk_wait_event(sk, timeo_p, |
| 75 | !sk->sk_err && |
| 76 | !((1 << sk->sk_state) & |
| 77 | ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))); |
| 78 | finish_wait(sk_sleep(sk), &wait); |
| 79 | sk->sk_write_pending--; |
| 80 | } while (!done); |
| 81 | return 0; |
| 82 | } |
| 83 | EXPORT_SYMBOL(sk_stream_wait_connect); |
| 84 | |
| 85 | /** |
| 86 | * sk_stream_closing - Return 1 if we still have things to send in our buffers. |
| 87 | * @sk: socket to verify |
| 88 | */ |
| 89 | static inline int sk_stream_closing(struct sock *sk) |
| 90 | { |
| 91 | return (1 << sk->sk_state) & |
| 92 | (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK); |
| 93 | } |
| 94 | |
| 95 | void sk_stream_wait_close(struct sock *sk, long timeout) |
| 96 | { |
| 97 | if (timeout) { |
| 98 | DEFINE_WAIT(wait); |
| 99 | |
| 100 | do { |
| 101 | prepare_to_wait(sk_sleep(sk), &wait, |
| 102 | TASK_INTERRUPTIBLE); |
| 103 | if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk))) |
| 104 | break; |
| 105 | } while (!signal_pending(current) && timeout); |
| 106 | |
| 107 | finish_wait(sk_sleep(sk), &wait); |
| 108 | } |
| 109 | } |
| 110 | EXPORT_SYMBOL(sk_stream_wait_close); |
| 111 | |
| 112 | /** |
| 113 | * sk_stream_wait_memory - Wait for more memory for a socket |
| 114 | * @sk: socket to wait for memory |
| 115 | * @timeo_p: for how long |
| 116 | */ |
| 117 | int sk_stream_wait_memory(struct sock *sk, long *timeo_p) |
| 118 | { |
| 119 | int err = 0; |
| 120 | long vm_wait = 0; |
| 121 | long current_timeo = *timeo_p; |
| 122 | bool noblock = (*timeo_p ? false : true); |
| 123 | DEFINE_WAIT(wait); |
| 124 | |
| 125 | if (sk_stream_memory_free(sk)) |
| 126 | current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2; |
| 127 | |
| 128 | while (1) { |
| 129 | sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); |
| 130 | |
| 131 | prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); |
| 132 | |
| 133 | if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) |
| 134 | goto do_error; |
| 135 | if (!*timeo_p) { |
| 136 | if (noblock) |
| 137 | set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); |
| 138 | goto do_nonblock; |
| 139 | } |
| 140 | if (signal_pending(current)) |
| 141 | goto do_interrupted; |
| 142 | sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); |
| 143 | if (sk_stream_memory_free(sk) && !vm_wait) |
| 144 | break; |
| 145 | |
| 146 | set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); |
| 147 | sk->sk_write_pending++; |
| 148 | sk_wait_event(sk, ¤t_timeo, sk->sk_err || |
| 149 | (sk->sk_shutdown & SEND_SHUTDOWN) || |
| 150 | (sk_stream_memory_free(sk) && |
| 151 | !vm_wait)); |
| 152 | sk->sk_write_pending--; |
| 153 | |
| 154 | if (vm_wait) { |
| 155 | vm_wait -= current_timeo; |
| 156 | current_timeo = *timeo_p; |
| 157 | if (current_timeo != MAX_SCHEDULE_TIMEOUT && |
| 158 | (current_timeo -= vm_wait) < 0) |
| 159 | current_timeo = 0; |
| 160 | vm_wait = 0; |
| 161 | } |
| 162 | *timeo_p = current_timeo; |
| 163 | } |
| 164 | out: |
| 165 | finish_wait(sk_sleep(sk), &wait); |
| 166 | return err; |
| 167 | |
| 168 | do_error: |
| 169 | err = -EPIPE; |
| 170 | goto out; |
| 171 | do_nonblock: |
| 172 | err = -EAGAIN; |
| 173 | goto out; |
| 174 | do_interrupted: |
| 175 | err = sock_intr_errno(*timeo_p); |
| 176 | goto out; |
| 177 | } |
| 178 | EXPORT_SYMBOL(sk_stream_wait_memory); |
| 179 | |
| 180 | int sk_stream_error(struct sock *sk, int flags, int err) |
| 181 | { |
| 182 | if (err == -EPIPE) |
| 183 | err = sock_error(sk) ? : -EPIPE; |
| 184 | if (err == -EPIPE && !(flags & MSG_NOSIGNAL)) |
| 185 | send_sig(SIGPIPE, current, 0); |
| 186 | return err; |
| 187 | } |
| 188 | EXPORT_SYMBOL(sk_stream_error); |
| 189 | |
| 190 | void sk_stream_kill_queues(struct sock *sk) |
| 191 | { |
| 192 | /* First the read buffer. */ |
| 193 | __skb_queue_purge(&sk->sk_receive_queue); |
| 194 | |
| 195 | /* Next, the error queue. */ |
| 196 | __skb_queue_purge(&sk->sk_error_queue); |
| 197 | |
| 198 | /* Next, the write queue. */ |
| 199 | WARN_ON(!skb_queue_empty(&sk->sk_write_queue)); |
| 200 | |
| 201 | /* Account for returned memory. */ |
| 202 | sk_mem_reclaim(sk); |
| 203 | |
| 204 | WARN_ON(sk->sk_wmem_queued); |
| 205 | WARN_ON(sk->sk_forward_alloc); |
| 206 | |
| 207 | /* It is _impossible_ for the backlog to contain anything |
| 208 | * when we get here. All user references to this socket |
| 209 | * have gone away, only the net layer knows can touch it. |
| 210 | */ |
| 211 | } |
| 212 | EXPORT_SYMBOL(sk_stream_kill_queues); |