// SPDX-License-Identifier: GPL-2.0/* *     SUCS NET3: * *     Generic stream handling routines. These are generic for most *     protocols. Even IP. Tonight 8-). *     This is used because TCP, LLC (others too) layer all have mostly *     identical sendmsg() and recvmsg() code. *     So we (will) share it here. * *     Authors:        Arnaldo Carvalho de Melo <acme@conectiva.com.br> *                     (from old tcp.c code) *                     Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-)) */ #include <linux/module.h>#include <linux/sched/signal.h>#include <linux/net.h>#include <linux/signal.h>#include <linux/tcp.h>#include <linux/wait.h>#include <net/sock.h> /** * sk_stream_write_space - stream socket write_space callback. * @sk: pointer to the socket structure * * This function is invoked when there's space available in the socket's * send buffer for writing. It first checks if the socket is writable, * clears the SOCK_NOSPACE flag indicating that memory for writing * is now available, wakes up any processes waiting for write operations * and sends asynchronous notifications if needed. */void sk_stream_write_space(struct sock *sk){	struct socket *sock = sk->sk_socket;	struct socket_wq *wq; 	if (__sk_stream_is_writeable(sk, 1) && sock) {		clear_bit(SOCK_NOSPACE, &sock->flags); 		rcu_read_lock();		wq = rcu_dereference(sk->sk_wq);		if (skwq_has_sleeper(wq))			wake_up_interruptible_poll(&wq->wait, EPOLLOUT |						EPOLLWRNORM | EPOLLWRBAND);		if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))			sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);		rcu_read_unlock();	}} /** * sk_stream_wait_connect - Wait for a socket to get into the connected state * @sk: sock to wait on * @timeo_p: for how long to wait * * Must be called with the socket locked. */int sk_stream_wait_connect(struct sock *sk, long *timeo_p){	DEFINE_WAIT_FUNC(wait, woken_wake_function);	struct task_struct *tsk = current;	int done; 	do {		int err = sock_error(sk);		if (err)			return err;		if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))			return -EPIPE;		if (!*timeo_p)			return -EAGAIN;		if (signal_pending(tsk))			return sock_intr_errno(*timeo_p); 		add_wait_queue(sk_sleep(sk), &wait);		sk->sk_write_pending++;		done = sk_wait_event(sk, timeo_p,				     !READ_ONCE(sk->sk_err) &&				     !((1 << READ_ONCE(sk->sk_state)) &				       ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait);		remove_wait_queue(sk_sleep(sk), &wait);		sk->sk_write_pending--;	} while (!done);	return done < 0 ? done : 0;}EXPORT_SYMBOL(sk_stream_wait_connect); /** * sk_stream_closing - Return 1 if we still have things to send in our buffers. * @sk: socket to verify */static int sk_stream_closing(const struct sock *sk){	return (1 << READ_ONCE(sk->sk_state)) &	       (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);} void sk_stream_wait_close(struct sock *sk, long timeout){	if (timeout) {		DEFINE_WAIT_FUNC(wait, woken_wake_function); 		add_wait_queue(sk_sleep(sk), &wait); 		do {			if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))				break;		} while (!signal_pending(current) && timeout); 		remove_wait_queue(sk_sleep(sk), &wait);	}} /** * sk_stream_wait_memory - Wait for more memory for a socket * @sk: socket to wait for memory * @timeo_p: for how long */int sk_stream_wait_memory(struct sock *sk, long *timeo_p){	int ret, err = 0;	long vm_wait = 0;	long current_timeo = *timeo_p;	DEFINE_WAIT_FUNC(wait, woken_wake_function); 	if (sk_stream_memory_free(sk))		current_timeo = vm_wait = get_random_u32_below(HZ / 5) + 2; 	add_wait_queue(sk_sleep(sk), &wait); 	while (1) {		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); 		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))			goto do_error;		if (!*timeo_p)			goto do_eagain;		if (signal_pending(current))			goto do_interrupted;		sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);		if (sk_stream_memory_free(sk) && !vm_wait)			break; 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);		sk->sk_write_pending++;		ret = sk_wait_event(sk, &current_timeo, READ_ONCE(sk->sk_err) ||				    (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) ||				    (sk_stream_memory_free(sk) && !vm_wait),				    &wait);		sk->sk_write_pending--;		if (ret < 0)			goto do_error; 		if (vm_wait) {			vm_wait -= current_timeo;			current_timeo = *timeo_p;			if (current_timeo != MAX_SCHEDULE_TIMEOUT &&			    (current_timeo -= vm_wait) < 0)				current_timeo = 0;			vm_wait = 0;		}		*timeo_p = current_timeo;	}out:	if (!sock_flag(sk, SOCK_DEAD))		remove_wait_queue(sk_sleep(sk), &wait);	return err; do_error:	err = -EPIPE;	goto out;do_eagain:	/* Make sure that whenever EAGAIN is returned, EPOLLOUT event can	 * be generated later.	 * When TCP receives ACK packets that make room, tcp_check_space()	 * only calls tcp_new_space() if SOCK_NOSPACE is set.	 */	set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);	err = -EAGAIN;	goto out;do_interrupted:	err = sock_intr_errno(*timeo_p);	goto out;}EXPORT_SYMBOL(sk_stream_wait_memory); int sk_stream_error(struct sock *sk, int flags, int err){	if (err == -EPIPE)		err = sock_error(sk) ? : -EPIPE;	if (err == -EPIPE && !(flags & MSG_NOSIGNAL))		send_sig(SIGPIPE, current, 0);	return err;}EXPORT_SYMBOL(sk_stream_error); void sk_stream_kill_queues(struct sock *sk){	/* First the read buffer. */	__skb_queue_purge(&sk->sk_receive_queue); 	/* Next, the error queue.	 * We need to use queue lock, because other threads might	 * add packets to the queue without socket lock being held.	 */	skb_queue_purge(&sk->sk_error_queue); 	/* Next, the write queue. */	WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue)); 	/* Account for returned memory. */	sk_mem_reclaim_final(sk); 	WARN_ON_ONCE(sk->sk_wmem_queued); 	/* It is _impossible_ for the backlog to contain anything	 * when we get here.  All user references to this socket	 * have gone away, only the net layer knows can touch it.	 */}EXPORT_SYMBOL(sk_stream_kill_queues);