GNU Linux-libre 4.4-gnu1
[releases.git] / 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@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 (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(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, &current_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);