xref: /openbmc/linux/net/core/stream.c (revision 2ef87ac5)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *     SUCS NET3:
4  *
5  *     Generic stream handling routines. These are generic for most
6  *     protocols. Even IP. Tonight 8-).
7  *     This is used because TCP, LLC (others too) layer all have mostly
8  *     identical sendmsg() and recvmsg() code.
9  *     So we (will) share it here.
10  *
11  *     Authors:        Arnaldo Carvalho de Melo <acme@conectiva.com.br>
12  *                     (from old tcp.c code)
13  *                     Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
14  */
15 
16 #include <linux/module.h>
17 #include <linux/sched/signal.h>
18 #include <linux/net.h>
19 #include <linux/signal.h>
20 #include <linux/tcp.h>
21 #include <linux/wait.h>
22 #include <net/sock.h>
23 
24 /**
25  * sk_stream_write_space - stream socket write_space callback.
26  * @sk: socket
27  *
28  * FIXME: write proper description
29  */
sk_stream_write_space(struct sock * sk)30 void sk_stream_write_space(struct sock *sk)
31 {
32 	struct socket *sock = sk->sk_socket;
33 	struct socket_wq *wq;
34 
35 	if (__sk_stream_is_writeable(sk, 1) && sock) {
36 		clear_bit(SOCK_NOSPACE, &sock->flags);
37 
38 		rcu_read_lock();
39 		wq = rcu_dereference(sk->sk_wq);
40 		if (skwq_has_sleeper(wq))
41 			wake_up_interruptible_poll(&wq->wait, EPOLLOUT |
42 						EPOLLWRNORM | EPOLLWRBAND);
43 		if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
44 			sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
45 		rcu_read_unlock();
46 	}
47 }
48 
49 /**
50  * sk_stream_wait_connect - Wait for a socket to get into the connected state
51  * @sk: sock to wait on
52  * @timeo_p: for how long to wait
53  *
54  * Must be called with the socket locked.
55  */
sk_stream_wait_connect(struct sock * sk,long * timeo_p)56 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
57 {
58 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
59 	struct task_struct *tsk = current;
60 	int done;
61 
62 	do {
63 		int err = sock_error(sk);
64 		if (err)
65 			return err;
66 		if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
67 			return -EPIPE;
68 		if (!*timeo_p)
69 			return -EAGAIN;
70 		if (signal_pending(tsk))
71 			return sock_intr_errno(*timeo_p);
72 
73 		add_wait_queue(sk_sleep(sk), &wait);
74 		sk->sk_write_pending++;
75 		done = sk_wait_event(sk, timeo_p,
76 				     !READ_ONCE(sk->sk_err) &&
77 				     !((1 << READ_ONCE(sk->sk_state)) &
78 				       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait);
79 		remove_wait_queue(sk_sleep(sk), &wait);
80 		sk->sk_write_pending--;
81 	} while (!done);
82 	return done < 0 ? done : 0;
83 }
84 EXPORT_SYMBOL(sk_stream_wait_connect);
85 
86 /**
87  * sk_stream_closing - Return 1 if we still have things to send in our buffers.
88  * @sk: socket to verify
89  */
sk_stream_closing(const struct sock * sk)90 static int sk_stream_closing(const struct sock *sk)
91 {
92 	return (1 << READ_ONCE(sk->sk_state)) &
93 	       (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
94 }
95 
sk_stream_wait_close(struct sock * sk,long timeout)96 void sk_stream_wait_close(struct sock *sk, long timeout)
97 {
98 	if (timeout) {
99 		DEFINE_WAIT_FUNC(wait, woken_wake_function);
100 
101 		add_wait_queue(sk_sleep(sk), &wait);
102 
103 		do {
104 			if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
105 				break;
106 		} while (!signal_pending(current) && timeout);
107 
108 		remove_wait_queue(sk_sleep(sk), &wait);
109 	}
110 }
111 EXPORT_SYMBOL(sk_stream_wait_close);
112 
113 /**
114  * sk_stream_wait_memory - Wait for more memory for a socket
115  * @sk: socket to wait for memory
116  * @timeo_p: for how long
117  */
sk_stream_wait_memory(struct sock * sk,long * timeo_p)118 int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
119 {
120 	int ret, err = 0;
121 	long vm_wait = 0;
122 	long current_timeo = *timeo_p;
123 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
124 
125 	if (sk_stream_memory_free(sk))
126 		current_timeo = vm_wait = get_random_u32_below(HZ / 5) + 2;
127 
128 	add_wait_queue(sk_sleep(sk), &wait);
129 
130 	while (1) {
131 		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
132 
133 		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
134 			goto do_error;
135 		if (!*timeo_p)
136 			goto do_eagain;
137 		if (signal_pending(current))
138 			goto do_interrupted;
139 		sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
140 		if (sk_stream_memory_free(sk) && !vm_wait)
141 			break;
142 
143 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
144 		sk->sk_write_pending++;
145 		ret = sk_wait_event(sk, &current_timeo, READ_ONCE(sk->sk_err) ||
146 				    (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) ||
147 				    (sk_stream_memory_free(sk) && !vm_wait),
148 				    &wait);
149 		sk->sk_write_pending--;
150 		if (ret < 0)
151 			goto do_error;
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 	if (!sock_flag(sk, SOCK_DEAD))
165 		remove_wait_queue(sk_sleep(sk), &wait);
166 	return err;
167 
168 do_error:
169 	err = -EPIPE;
170 	goto out;
171 do_eagain:
172 	/* Make sure that whenever EAGAIN is returned, EPOLLOUT event can
173 	 * be generated later.
174 	 * When TCP receives ACK packets that make room, tcp_check_space()
175 	 * only calls tcp_new_space() if SOCK_NOSPACE is set.
176 	 */
177 	set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
178 	err = -EAGAIN;
179 	goto out;
180 do_interrupted:
181 	err = sock_intr_errno(*timeo_p);
182 	goto out;
183 }
184 EXPORT_SYMBOL(sk_stream_wait_memory);
185 
sk_stream_error(struct sock * sk,int flags,int err)186 int sk_stream_error(struct sock *sk, int flags, int err)
187 {
188 	if (err == -EPIPE)
189 		err = sock_error(sk) ? : -EPIPE;
190 	if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
191 		send_sig(SIGPIPE, current, 0);
192 	return err;
193 }
194 EXPORT_SYMBOL(sk_stream_error);
195 
sk_stream_kill_queues(struct sock * sk)196 void sk_stream_kill_queues(struct sock *sk)
197 {
198 	/* First the read buffer. */
199 	__skb_queue_purge(&sk->sk_receive_queue);
200 
201 	/* Next, the error queue.
202 	 * We need to use queue lock, because other threads might
203 	 * add packets to the queue without socket lock being held.
204 	 */
205 	skb_queue_purge(&sk->sk_error_queue);
206 
207 	/* Next, the write queue. */
208 	WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue));
209 
210 	/* Account for returned memory. */
211 	sk_mem_reclaim_final(sk);
212 
213 	WARN_ON_ONCE(sk->sk_wmem_queued);
214 
215 	/* It is _impossible_ for the backlog to contain anything
216 	 * when we get here.  All user references to this socket
217 	 * have gone away, only the net layer knows can touch it.
218 	 */
219 }
220 EXPORT_SYMBOL(sk_stream_kill_queues);
221