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) && 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 !sk->sk_err &&
77 !((1 << 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 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(struct sock * sk)90 static inline int sk_stream_closing(struct sock *sk)
91 {
92 return (1 << 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 err = 0;
121 long vm_wait = 0;
122 long current_timeo = *timeo_p;
123 bool noblock = (*timeo_p ? false : true);
124 DEFINE_WAIT_FUNC(wait, woken_wake_function);
125
126 if (sk_stream_memory_free(sk))
127 current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2;
128
129 add_wait_queue(sk_sleep(sk), &wait);
130
131 while (1) {
132 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
133
134 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
135 goto do_error;
136 if (!*timeo_p) {
137 if (noblock)
138 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
139 goto do_nonblock;
140 }
141 if (signal_pending(current))
142 goto do_interrupted;
143 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
144 if (sk_stream_memory_free(sk) && !vm_wait)
145 break;
146
147 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
148 sk->sk_write_pending++;
149 sk_wait_event(sk, ¤t_timeo, sk->sk_err ||
150 (sk->sk_shutdown & SEND_SHUTDOWN) ||
151 (sk_stream_memory_free(sk) &&
152 !vm_wait), &wait);
153 sk->sk_write_pending--;
154
155 if (vm_wait) {
156 vm_wait -= current_timeo;
157 current_timeo = *timeo_p;
158 if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
159 (current_timeo -= vm_wait) < 0)
160 current_timeo = 0;
161 vm_wait = 0;
162 }
163 *timeo_p = current_timeo;
164 }
165 out:
166 remove_wait_queue(sk_sleep(sk), &wait);
167 return err;
168
169 do_error:
170 err = -EPIPE;
171 goto out;
172 do_nonblock:
173 err = -EAGAIN;
174 goto out;
175 do_interrupted:
176 err = sock_intr_errno(*timeo_p);
177 goto out;
178 }
179 EXPORT_SYMBOL(sk_stream_wait_memory);
180
sk_stream_error(struct sock * sk,int flags,int err)181 int sk_stream_error(struct sock *sk, int flags, int err)
182 {
183 if (err == -EPIPE)
184 err = sock_error(sk) ? : -EPIPE;
185 if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
186 send_sig(SIGPIPE, current, 0);
187 return err;
188 }
189 EXPORT_SYMBOL(sk_stream_error);
190
sk_stream_kill_queues(struct sock * sk)191 void sk_stream_kill_queues(struct sock *sk)
192 {
193 /* First the read buffer. */
194 __skb_queue_purge(&sk->sk_receive_queue);
195
196 /* Next, the error queue. */
197 __skb_queue_purge(&sk->sk_error_queue);
198
199 /* Next, the write queue. */
200 WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
201
202 /* Account for returned memory. */
203 sk_mem_reclaim(sk);
204
205 WARN_ON(sk->sk_wmem_queued);
206 WARN_ON(sk->sk_forward_alloc);
207
208 /* It is _impossible_ for the backlog to contain anything
209 * when we get here. All user references to this socket
210 * have gone away, only the net layer knows can touch it.
211 */
212 }
213 EXPORT_SYMBOL(sk_stream_kill_queues);
214
