path: root/net/rxrpc/sendmsg.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* AF_RXRPC sendmsg() implementation.
 *
 * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/net.h>
#include <linux/gfp.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <linux/sched/signal.h>

#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Return true if there's sufficient Tx queue space.
 */
static bool rxrpc_check_tx_space(struct rxrpc_call *call, rxrpc_seq_t *_tx_win)
{
	unsigned int win_size =
		min_t(unsigned int, call->tx_winsize,
		      call->cong_cwnd + call->cong_extra);
	rxrpc_seq_t tx_win = READ_ONCE(call->tx_hard_ack);

	if (_tx_win)
		*_tx_win = tx_win;
	return call->tx_top - tx_win < win_size;
}

/*
 * Wait for space to appear in the Tx queue or a signal to occur.
 */
static int rxrpc_wait_for_tx_window_intr(struct rxrpc_sock *rx,
					 struct rxrpc_call *call,
					 long *timeo)
{
	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);
		if (rxrpc_check_tx_space(call, NULL))
			return 0;

		if (call->state >= RXRPC_CALL_COMPLETE)
			return call->error;

		if (signal_pending(current))
			return sock_intr_errno(*timeo);

		trace_rxrpc_transmit(call, rxrpc_transmit_wait);
		mutex_unlock(&call->user_mutex);
		*timeo = schedule_timeout(*timeo);
		if (mutex_lock_interruptible(&call->user_mutex) < 0)
			return sock_intr_errno(*timeo);
	}
}

/*
 * Wait for space to appear in the Tx queue uninterruptibly, but with
 * a timeout of 2*RTT if no progress was made and a signal occurred.
 */
static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx,
					    struct rxrpc_call *call)
{
	rxrpc_seq_t tx_start, tx_win;
	signed long rtt, timeout;

	rtt = READ_ONCE(call->peer->srtt_us) >> 3;
	rtt = usecs_to_jiffies(rtt) * 2;
	if (rtt < 2)
		rtt = 2;

	timeout = rtt;
	tx_start = READ_ONCE(call->tx_hard_ack);

	for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);

		tx_win = READ_ONCE(call->tx_hard_ack);
		if (rxrpc_check_tx_space(call, &tx_win))
			return 0;

		if (call->state >= RXRPC_CALL_COMPLETE)
			return call->error;

		if (timeout == 0 &&
		    tx_win == tx_start && signal_pending(current))
			return -EINTR;

		if (tx_win != tx_start) {
			timeout = rtt;
			tx_start = tx_win;
		}

		trace_rxrpc_transmit(call, rxrpc_transmit_wait);
		timeout = schedule_timeout(timeout);
	}
}

/*
 * Wait for space to appear in the Tx queue uninterruptibly.
 */
static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
					    struct rxrpc_call *call,
					    long *timeo)
{
	for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (rxrpc_check_tx_space(call, NULL))
			return 0;

		if (call->state >= RXRPC_CALL_COMPLETE)
			return call->error;

		trace_rxrpc_transmit(call, rxrpc_transmit_wait);
		*timeo = schedule_timeout(*timeo);
	}
}

/*
 * wait for space to appear in the transmit/ACK window
 * - caller holds the socket locked
 */
static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
				    struct rxrpc_call *call,
				    long *timeo,
				    bool waitall)
{
	DECLARE_WAITQUEUE(myself, current);
	int ret;

	_enter(",{%u,%u,%u}",
	       call->tx_hard_ack, call->tx_top, call->tx_winsize);

	add_wait_queue(&call->waitq, &myself);

	switch (call->interruptibility) {
	case RXRPC_INTERRUPTIBLE:
		if (waitall)
			ret = rxrpc_wait_for_tx_window_waitall(rx, call);
		else
			ret = rxrpc_wait_for_tx_window_intr(rx, call, timeo);
		break;
	case RXRPC_PREINTERRUPTIBLE:
	case RXRPC_UNINTERRUPTIBLE:
	default:
		ret = rxrpc_wait_for_tx_window_nonintr(rx, call, timeo);
		break;
	}

	remove_wait_queue(&call->waitq, &myself);
	set_current_state(TASK_RUNNING);
	_leave(" = %d", ret);
	return ret;
}

/*
 * Schedule an instant Tx resend.
 */
static inline void rxrpc_instant_resend(struct rxrpc_call *call, int ix)
{
	spin_lock_bh(&call->lock);

	if (call->state < RXRPC_CALL_COMPLETE) {
		call->rxtx_annotations[ix] =
			(call->rxtx_annotations[ix] & RXRPC_TX_ANNO_LAST) |
			RXRPC_TX_ANNO_RETRANS;
		if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
			rxrpc_queue_call(call);
	}

	spin_unlock_bh(&call->lock);
}

/*
 * Notify the owner of the call that the transmit phase is ended and the last
 * packet has been queued.
 */
static void rxrpc_notify_end_tx(struct rxrpc_sock *rx,