xref: /openbmc/linux/net/core/stream.c (revision ebb9a9ae)
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, &current_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