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