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 */
sk_stream_write_space(struct sock * sk)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_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
34 clear_bit(SOCK_NOSPACE, &sock->flags);
35
36 rcu_read_lock();
37 wq = rcu_dereference(sk->sk_wq);
38 if (wq_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(sock, 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 */
sk_stream_wait_connect(struct sock * sk,long * timeo_p)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 */
sk_stream_closing(struct sock * sk)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
sk_stream_wait_close(struct sock * sk,long timeout)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 */
sk_stream_wait_memory(struct sock * sk,long * timeo_p)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 DEFINE_WAIT(wait);
123
124 if (sk_stream_memory_free(sk))
125 current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
126
127 while (1) {
128 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
129
130 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
131
132 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
133 goto do_error;
134 if (!*timeo_p)
135 goto do_nonblock;
136 if (signal_pending(current))
137 goto do_interrupted;
138 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
139 if (sk_stream_memory_free(sk) && !vm_wait)
140 break;
141
142 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
143 sk->sk_write_pending++;
144 sk_wait_event(sk, ¤t_timeo, sk->sk_err ||
145 (sk->sk_shutdown & SEND_SHUTDOWN) ||
146 (sk_stream_memory_free(sk) &&
147 !vm_wait));
148 sk->sk_write_pending--;
149
150 if (vm_wait) {
151 vm_wait -= current_timeo;
152 current_timeo = *timeo_p;
153 if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
154 (current_timeo -= vm_wait) < 0)
155 current_timeo = 0;
156 vm_wait = 0;
157 }
158 *timeo_p = current_timeo;
159 }
160 out:
161 finish_wait(sk_sleep(sk), &wait);
162 return err;
163
164 do_error:
165 err = -EPIPE;
166 goto out;
167 do_nonblock:
168 err = -EAGAIN;
169 goto out;
170 do_interrupted:
171 err = sock_intr_errno(*timeo_p);
172 goto out;
173 }
174 EXPORT_SYMBOL(sk_stream_wait_memory);
175
sk_stream_error(struct sock * sk,int flags,int err)176 int sk_stream_error(struct sock *sk, int flags, int err)
177 {
178 if (err == -EPIPE)
179 err = sock_error(sk) ? : -EPIPE;
180 if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
181 send_sig(SIGPIPE, current, 0);
182 return err;
183 }
184 EXPORT_SYMBOL(sk_stream_error);
185
sk_stream_kill_queues(struct sock * sk)186 void sk_stream_kill_queues(struct sock *sk)
187 {
188 /* First the read buffer. */
189 __skb_queue_purge(&sk->sk_receive_queue);
190
191 /* Next, the error queue. */
192 __skb_queue_purge(&sk->sk_error_queue);
193
194 /* Next, the write queue. */
195 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
196
197 /* Account for returned memory. */
198 sk_mem_reclaim(sk);
199
200 WARN_ON(sk->sk_wmem_queued);
201 WARN_ON(sk->sk_forward_alloc);
202
203 /* It is _impossible_ for the backlog to contain anything
204 * when we get here. All user references to this socket
205 * have gone away, only the net layer knows can touch it.
206 */
207 }
208 EXPORT_SYMBOL(sk_stream_kill_queues);
209