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/net/core/stream.c

http://github.com/mirrors/linux
C | 215 lines | 139 code | 27 blank | 49 comment | 31 complexity | f22516325e8f44762a7264f528a56d89 MD5 | raw file
  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 */
 30void 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 */
 56int 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}
 84EXPORT_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 */
 90static 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
 96void 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}
111EXPORT_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 */
118int 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	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			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		sk_wait_event(sk, &current_timeo, sk->sk_err ||
146						  (sk->sk_shutdown & SEND_SHUTDOWN) ||
147						  (sk_stream_memory_free(sk) &&
148						  !vm_wait), &wait);
149		sk->sk_write_pending--;
150
151		if (vm_wait) {
152			vm_wait -= current_timeo;
153			current_timeo = *timeo_p;
154			if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
155			    (current_timeo -= vm_wait) < 0)
156				current_timeo = 0;
157			vm_wait = 0;
158		}
159		*timeo_p = current_timeo;
160	}
161out:
162	remove_wait_queue(sk_sleep(sk), &wait);
163	return err;
164
165do_error:
166	err = -EPIPE;
167	goto out;
168do_eagain:
169	/* Make sure that whenever EAGAIN is returned, EPOLLOUT event can
170	 * be generated later.
171	 * When TCP receives ACK packets that make room, tcp_check_space()
172	 * only calls tcp_new_space() if SOCK_NOSPACE is set.
173	 */
174	set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
175	err = -EAGAIN;
176	goto out;
177do_interrupted:
178	err = sock_intr_errno(*timeo_p);
179	goto out;
180}
181EXPORT_SYMBOL(sk_stream_wait_memory);
182
183int sk_stream_error(struct sock *sk, int flags, int err)
184{
185	if (err == -EPIPE)
186		err = sock_error(sk) ? : -EPIPE;
187	if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
188		send_sig(SIGPIPE, current, 0);
189	return err;
190}
191EXPORT_SYMBOL(sk_stream_error);
192
193void sk_stream_kill_queues(struct sock *sk)
194{
195	/* First the read buffer. */
196	__skb_queue_purge(&sk->sk_receive_queue);
197
198	/* Next, the error queue. */
199	__skb_queue_purge(&sk->sk_error_queue);
200
201	/* Next, the write queue. */
202	WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
203
204	/* Account for returned memory. */
205	sk_mem_reclaim(sk);
206
207	WARN_ON(sk->sk_wmem_queued);
208	WARN_ON(sk->sk_forward_alloc);
209
210	/* It is _impossible_ for the backlog to contain anything
211	 * when we get here.  All user references to this socket
212	 * have gone away, only the net layer knows can touch it.
213	 */
214}
215EXPORT_SYMBOL(sk_stream_kill_queues);