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 */
28void 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}
46EXPORT_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 */
55int 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}
83EXPORT_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 */
89static 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
95void 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}
110EXPORT_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 */
117int 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	}
164out:
165	finish_wait(sk_sleep(sk), &wait);
166	return err;
167
168do_error:
169	err = -EPIPE;
170	goto out;
171do_nonblock:
172	err = -EAGAIN;
173	goto out;
174do_interrupted:
175	err = sock_intr_errno(*timeo_p);
176	goto out;
177}
178EXPORT_SYMBOL(sk_stream_wait_memory);
179
180int 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}
188EXPORT_SYMBOL(sk_stream_error);
189
190void 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}
212EXPORT_SYMBOL(sk_stream_kill_queues);
213