xref: /openbmc/linux/net/core/stream.c (revision 9ac8d3fb)
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 
32 	if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
33 		clear_bit(SOCK_NOSPACE, &sock->flags);
34 
35 		if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
36 			wake_up_interruptible(sk->sk_sleep);
37 		if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
38 			sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
39 	}
40 }
41 
42 EXPORT_SYMBOL(sk_stream_write_space);
43 
44 /**
45  * sk_stream_wait_connect - Wait for a socket to get into the connected state
46  * @sk: sock to wait on
47  * @timeo_p: for how long to wait
48  *
49  * Must be called with the socket locked.
50  */
51 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
52 {
53 	struct task_struct *tsk = current;
54 	DEFINE_WAIT(wait);
55 	int done;
56 
57 	do {
58 		int err = sock_error(sk);
59 		if (err)
60 			return err;
61 		if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
62 			return -EPIPE;
63 		if (!*timeo_p)
64 			return -EAGAIN;
65 		if (signal_pending(tsk))
66 			return sock_intr_errno(*timeo_p);
67 
68 		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
69 		sk->sk_write_pending++;
70 		done = sk_wait_event(sk, timeo_p,
71 				     !sk->sk_err &&
72 				     !((1 << sk->sk_state) &
73 				       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
74 		finish_wait(sk->sk_sleep, &wait);
75 		sk->sk_write_pending--;
76 	} while (!done);
77 	return 0;
78 }
79 
80 EXPORT_SYMBOL(sk_stream_wait_connect);
81 
82 /**
83  * sk_stream_closing - Return 1 if we still have things to send in our buffers.
84  * @sk: socket to verify
85  */
86 static inline int sk_stream_closing(struct sock *sk)
87 {
88 	return (1 << sk->sk_state) &
89 	       (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
90 }
91 
92 void sk_stream_wait_close(struct sock *sk, long timeout)
93 {
94 	if (timeout) {
95 		DEFINE_WAIT(wait);
96 
97 		do {
98 			prepare_to_wait(sk->sk_sleep, &wait,
99 					TASK_INTERRUPTIBLE);
100 			if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
101 				break;
102 		} while (!signal_pending(current) && timeout);
103 
104 		finish_wait(sk->sk_sleep, &wait);
105 	}
106 }
107 
108 EXPORT_SYMBOL(sk_stream_wait_close);
109 
110 /**
111  * sk_stream_wait_memory - Wait for more memory for a socket
112  * @sk: socket to wait for memory
113  * @timeo_p: for how long
114  */
115 int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
116 {
117 	int err = 0;
118 	long vm_wait = 0;
119 	long current_timeo = *timeo_p;
120 	DEFINE_WAIT(wait);
121 
122 	if (sk_stream_memory_free(sk))
123 		current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
124 
125 	while (1) {
126 		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
127 
128 		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
129 
130 		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
131 			goto do_error;
132 		if (!*timeo_p)
133 			goto do_nonblock;
134 		if (signal_pending(current))
135 			goto do_interrupted;
136 		clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
137 		if (sk_stream_memory_free(sk) && !vm_wait)
138 			break;
139 
140 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
141 		sk->sk_write_pending++;
142 		sk_wait_event(sk, &current_timeo, !sk->sk_err &&
143 						  !(sk->sk_shutdown & SEND_SHUTDOWN) &&
144 						  sk_stream_memory_free(sk) &&
145 						  vm_wait);
146 		sk->sk_write_pending--;
147 
148 		if (vm_wait) {
149 			vm_wait -= current_timeo;
150 			current_timeo = *timeo_p;
151 			if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
152 			    (current_timeo -= vm_wait) < 0)
153 				current_timeo = 0;
154 			vm_wait = 0;
155 		}
156 		*timeo_p = current_timeo;
157 	}
158 out:
159 	finish_wait(sk->sk_sleep, &wait);
160 	return err;
161 
162 do_error:
163 	err = -EPIPE;
164 	goto out;
165 do_nonblock:
166 	err = -EAGAIN;
167 	goto out;
168 do_interrupted:
169 	err = sock_intr_errno(*timeo_p);
170 	goto out;
171 }
172 
173 EXPORT_SYMBOL(sk_stream_wait_memory);
174 
175 int sk_stream_error(struct sock *sk, int flags, int err)
176 {
177 	if (err == -EPIPE)
178 		err = sock_error(sk) ? : -EPIPE;
179 	if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
180 		send_sig(SIGPIPE, current, 0);
181 	return err;
182 }
183 
184 EXPORT_SYMBOL(sk_stream_error);
185 
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 
209 EXPORT_SYMBOL(sk_stream_kill_queues);
210