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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/sched/signal.h>
17 #include <linux/net.h>
18 #include <linux/signal.h>
19 #include <linux/tcp.h>
20 #include <linux/wait.h>
21 #include <net/sock.h>
22
23 /**
24 * sk_stream_write_space - stream socket write_space callback.
25 * @sk: socket
26 *
27 * FIXME: write proper description
28 */
29 void sk_stream_write_space(struct sock *sk)
30 {
31 struct socket *sock = sk->sk_socket;
32 struct socket_wq *wq;
33
34 if (sk_stream_is_writeable(sk) && sock) {
35 clear_bit(SOCK_NOSPACE, &sock->flags);
36
37 rcu_read_lock();
38 wq = rcu_dereference(sk->sk_wq);
39 if (skwq_has_sleeper(wq))
40 wake_up_interruptible_poll(&wq->wait, POLLOUT |
41 POLLWRNORM | POLLWRBAND);
42 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
43 sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
44 rcu_read_unlock();
45 }
46 }
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 */
55 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
56 {
57 DEFINE_WAIT_FUNC(wait, woken_wake_function);
58 struct task_struct *tsk = current;
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 add_wait_queue(sk_sleep(sk), &wait);
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)), &wait);
78 remove_wait_queue(sk_sleep(sk), &wait);
79 sk->sk_write_pending--;
80 } while (!done);
81 return 0;
82 }
83 EXPORT_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 */
89 static 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
95 void sk_stream_wait_close(struct sock *sk, long timeout)
96 {
97 if (timeout) {
98 DEFINE_WAIT_FUNC(wait, woken_wake_function);
99
100 add_wait_queue(sk_sleep(sk), &wait);
101
102 do {
103 if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
104 break;
105 } while (!signal_pending(current) && timeout);
106
107 remove_wait_queue(sk_sleep(sk), &wait);
108 }
109 }
110 EXPORT_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 */
117 int 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_FUNC(wait, woken_wake_function);
124
125 if (sk_stream_memory_free(sk))
126 current_timeo = vm_wait = (prandom_u32() % (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 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), &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 }
164 out:
165 remove_wait_queue(sk_sleep(sk), &wait);
166 return err;
167
168 do_error:
169 err = -EPIPE;
170 goto out;
171 do_nonblock:
172 err = -EAGAIN;
173 goto out;
174 do_interrupted:
175 err = sock_intr_errno(*timeo_p);
176 goto out;
177 }
178 EXPORT_SYMBOL(sk_stream_wait_memory);
179
180 int 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 }
188 EXPORT_SYMBOL(sk_stream_error);
189
190 void 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 }
212 EXPORT_SYMBOL(sk_stream_kill_queues);