net/rxrpc/sendmsg.c - pub/scm/linux/kernel/git/viro/vfs - Git at Google

 // 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"

 /*
  * 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 (call->tx_top - call->tx_hard_ack <
 		    min_t(unsigned int, call->tx_winsize,
 			  call->cong_cwnd + call->cong_extra))
 			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_nonintr(struct rxrpc_sock *rx,
 					    struct rxrpc_call *call)
 {
 	rxrpc_seq_t tx_start, tx_win;
 	signed long rtt2, timeout;
 	u64 rtt;

 	rtt = READ_ONCE(call->peer->rtt);
 	rtt2 = nsecs_to_jiffies64(rtt) * 2;
 	if (rtt2 < 1)
 		rtt2 = 1;

 	timeout = rtt2;
 	tx_start = READ_ONCE(call->tx_hard_ack);

 	for (;;) {
 		set_current_state(TASK_UNINTERRUPTIBLE);

 		tx_win = READ_ONCE(call->tx_hard_ack);
 		if (call->tx_top - tx_win <
 		    min_t(unsigned int, call->tx_winsize,
 			  call->cong_cwnd + call->cong_extra))
 			return 0;

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

 		if (test_bit(RXRPC_CALL_IS_INTR, &call->flags) &&
 		    timeout == 0 &&
 		    tx_win == tx_start && signal_pending(current))
 			return -EINTR;

 		if (tx_win != tx_start) {
 			timeout = rtt2;
 			tx_start = tx_win;
 		}

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

 /*
  * 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);

 	if (waitall)
 		ret = rxrpc_wait_for_tx_window_nonintr(rx, call);
 	else
 		ret = rxrpc_wait_for_tx_window_intr(rx, call, timeo);

 	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, struct rxrpc_call *call,
 				rxrpc_notify_end_tx_t notify_end_tx)
 {
 	if (notify_end_tx)
 		notify_end_tx(&rx->sk, call, call->user_call_ID);
 }

 /*
  * Queue a DATA packet for transmission, set the resend timeout and send
  * the packet immediately.  Returns the error from rxrpc_send_data_packet()
  * in case the caller wants to do something with it.
  */
 static int rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call,
 			      struct sk_buff *skb, bool last,
 			      rxrpc_notify_end_tx_t notify_end_tx)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	unsigned long now;
 	rxrpc_seq_t seq = sp->hdr.seq;
 	int ret, ix;
 	u8 annotation = RXRPC_TX_ANNO_UNACK;

 	_net("queue skb %p [%d]", skb, seq);

 	ASSERTCMP(seq, ==, call->tx_top + 1);

 	if (last)
 		annotation |= RXRPC_TX_ANNO_LAST;

 	/* We have to set the timestamp before queueing as the retransmit
 	 * algorithm can see the packet as soon as we queue it.
 	 */
 	skb->tstamp = ktime_get_real();

 	ix = seq & RXRPC_RXTX_BUFF_MASK;
 	rxrpc_get_skb(skb, rxrpc_skb_got);
 	call->rxtx_annotations[ix] = annotation;
 	smp_wmb();
 	call->rxtx_buffer[ix] = skb;
 	call->tx_top = seq;
 	if (last)
 		trace_rxrpc_transmit(call, rxrpc_transmit_queue_last);
 	else
 		trace_rxrpc_transmit(call, rxrpc_transmit_queue);

 	if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
 		_debug("________awaiting reply/ACK__________");
 		write_lock_bh(&call->state_lock);
 		switch (call->state) {
 		case RXRPC_CALL_CLIENT_SEND_REQUEST:
 			call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 			rxrpc_notify_end_tx(rx, call, notify_end_tx);
 			break;
 		case RXRPC_CALL_SERVER_ACK_REQUEST:
 			call->state = RXRPC_CALL_SERVER_SEND_REPLY;
 			now = jiffies;
 			WRITE_ONCE(call->ack_at, now + MAX_JIFFY_OFFSET);
 			if (call->ackr_reason == RXRPC_ACK_DELAY)
 				call->ackr_reason = 0;
 			trace_rxrpc_timer(call, rxrpc_timer_init_for_send_reply, now);
 			if (!last)
 				break;
 			/* Fall through */
 		case RXRPC_CALL_SERVER_SEND_REPLY:
 			call->state = RXRPC_CALL_SERVER_AWAIT_ACK;
 			rxrpc_notify_end_tx(rx, call, notify_end_tx);
 			break;
 		default:
 			break;
 		}
 		write_unlock_bh(&call->state_lock);
 	}

 	if (seq == 1 && rxrpc_is_client_call(call))
 		rxrpc_expose_client_call(call);

 	ret = rxrpc_send_data_packet(call, skb, false);
 	if (ret < 0) {
 		switch (ret) {
 		case -ENETUNREACH:
 		case -EHOSTUNREACH:
 		case -ECONNREFUSED:
 			rxrpc_set_call_completion(call,
 						  RXRPC_CALL_LOCAL_ERROR,
 						  0, ret);
 			rxrpc_notify_socket(call);
 			goto out;
 		}
 		_debug("need instant resend %d", ret);
 		rxrpc_instant_resend(call, ix);
 	} else {
 		unsigned long now = jiffies, resend_at;

 		if (call->peer->rtt_usage > 1)
 			resend_at = nsecs_to_jiffies(call->peer->rtt * 3 / 2);
 		else
 			resend_at = rxrpc_resend_timeout;
 		if (resend_at < 1)
 			resend_at = 1;

 		resend_at += now;
 		WRITE_ONCE(call->resend_at, resend_at);
 		rxrpc_reduce_call_timer(call, resend_at, now,
 					rxrpc_timer_set_for_send);
 	}

 out:
 	rxrpc_free_skb(skb, rxrpc_skb_freed);
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * send data through a socket
  * - must be called in process context
  * - The caller holds the call user access mutex, but not the socket lock.
  */
 static int rxrpc_send_data(struct rxrpc_sock *rx,
 			   struct rxrpc_call *call,
 			   struct msghdr *msg, size_t len,
 			   rxrpc_notify_end_tx_t notify_end_tx)
 {
 	struct rxrpc_skb_priv *sp;
 	struct sk_buff *skb;
 	struct sock *sk = &rx->sk;
 	long timeo;
 	bool more;
 	int ret, copied;

 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);

 	/* this should be in poll */
 	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);

 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 		return -EPIPE;

 	more = msg->msg_flags & MSG_MORE;

 	if (call->tx_total_len != -1) {
 		if (len > call->tx_total_len)
 			return -EMSGSIZE;
 		if (!more && len != call->tx_total_len)
 			return -EMSGSIZE;
 	}

 	skb = call->tx_pending;
 	call->tx_pending = NULL;
 	rxrpc_see_skb(skb, rxrpc_skb_seen);

 	copied = 0;
 	do {
 		/* Check to see if there's a ping ACK to reply to. */
 		if (call->ackr_reason == RXRPC_ACK_PING_RESPONSE)
 			rxrpc_send_ack_packet(call, false, NULL);

 		if (!skb) {
 			size_t size, chunk, max, space;

 			_debug("alloc");

 			if (call->tx_top - call->tx_hard_ack >=
 			    min_t(unsigned int, call->tx_winsize,
 				  call->cong_cwnd + call->cong_extra)) {
 				ret = -EAGAIN;
 				if (msg->msg_flags & MSG_DONTWAIT)
 					goto maybe_error;
 				ret = rxrpc_wait_for_tx_window(rx, call,
 							       &timeo,
 							       msg->msg_flags & MSG_WAITALL);
 				if (ret < 0)
 					goto maybe_error;
 			}

 			max = RXRPC_JUMBO_DATALEN;
 			max -= call->conn->security_size;
 			max &= ~(call->conn->size_align - 1UL);

 			chunk = max;
 			if (chunk > msg_data_left(msg) && !more)
 				chunk = msg_data_left(msg);

 			space = chunk + call->conn->size_align;
 			space &= ~(call->conn->size_align - 1UL);

 			size = space + call->conn->security_size;

 			_debug("SIZE: %zu/%zu/%zu", chunk, space, size);

 			/* create a buffer that we can retain until it's ACK'd */
 			skb = sock_alloc_send_skb(
 				sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
 			if (!skb)
 				goto maybe_error;

 			sp = rxrpc_skb(skb);
 			sp->rx_flags |= RXRPC_SKB_TX_BUFFER;
 			rxrpc_new_skb(skb, rxrpc_skb_new);

 			_debug("ALLOC SEND %p", skb);

 			ASSERTCMP(skb->mark, ==, 0);

 			_debug("HS: %u", call->conn->security_size);
 			skb_reserve(skb, call->conn->security_size);
 			skb->len += call->conn->security_size;

 			sp->remain = chunk;
 			if (sp->remain > skb_tailroom(skb))
 				sp->remain = skb_tailroom(skb);

 			_net("skb: hr %d, tr %d, hl %d, rm %d",
 			       skb_headroom(skb),
 			       skb_tailroom(skb),
 			       skb_headlen(skb),
 			       sp->remain);

 			skb->ip_summed = CHECKSUM_UNNECESSARY;
 		}

 		_debug("append");
 		sp = rxrpc_skb(skb);

 		/* append next segment of data to the current buffer */
 		if (msg_data_left(msg) > 0) {
 			int copy = skb_tailroom(skb);
 			ASSERTCMP(copy, >, 0);
 			if (copy > msg_data_left(msg))
 				copy = msg_data_left(msg);
 			if (copy > sp->remain)
 				copy = sp->remain;

 			_debug("add");
 			ret = skb_add_data(skb, &msg->msg_iter, copy);
 			_debug("added");
 			if (ret < 0)
 				goto efault;
 			sp->remain -= copy;
 			skb->mark += copy;
 			copied += copy;
 			if (call->tx_total_len != -1)
 				call->tx_total_len -= copy;
 		}

 		/* check for the far side aborting the call or a network error
 		 * occurring */
 		if (call->state == RXRPC_CALL_COMPLETE)
 			goto call_terminated;

 		/* add the packet to the send queue if it's now full */
 		if (sp->remain <= 0 ||
 		    (msg_data_left(msg) == 0 && !more)) {
 			struct rxrpc_connection *conn = call->conn;
 			uint32_t seq;
 			size_t pad;

 			/* pad out if we're using security */
 			if (conn->security_ix) {
 				pad = conn->security_size + skb->mark;
 				pad = conn->size_align - pad;
 				pad &= conn->size_align - 1;
 				_debug("pad %zu", pad);
 				if (pad)
 					skb_put_zero(skb, pad);
 			}

 			seq = call->tx_top + 1;

 			sp->hdr.seq	= seq;
 			sp->hdr._rsvd	= 0;
 			sp->hdr.flags	= conn->out_clientflag;

 			if (msg_data_left(msg) == 0 && !more)
 				sp->hdr.flags |= RXRPC_LAST_PACKET;
 			else if (call->tx_top - call->tx_hard_ack <
 				 call->tx_winsize)
 				sp->hdr.flags |= RXRPC_MORE_PACKETS;

 			ret = call->security->secure_packet(
 				call, skb, skb->mark, skb->head);
 			if (ret < 0)
 				goto out;

 			ret = rxrpc_queue_packet(rx, call, skb,
 						 !msg_data_left(msg) && !more,
 						 notify_end_tx);
 			/* Should check for failure here */
 			skb = NULL;
 		}
 	} while (msg_data_left(msg) > 0);

 success:
 	ret = copied;
 out:
 	call->tx_pending = skb;
 	_leave(" = %d", ret);
 	return ret;

 call_terminated:
 	rxrpc_free_skb(skb, rxrpc_skb_freed);
 	_leave(" = %d", call->error);
 	return call->error;

 maybe_error:
 	if (copied)
 		goto success;
 	goto out;

 efault:
 	ret = -EFAULT;
 	goto out;
 }

 /*
  * extract control messages from the sendmsg() control buffer
  */
 static int rxrpc_sendmsg_cmsg(struct msghdr *msg, struct rxrpc_send_params *p)
 {
 	struct cmsghdr *cmsg;
 	bool got_user_ID = false;
 	int len;

 	if (msg->msg_controllen == 0)
 		return -EINVAL;

 	for_each_cmsghdr(cmsg, msg) {
 		if (!CMSG_OK(msg, cmsg))
 			return -EINVAL;

 		len = cmsg->cmsg_len - sizeof(struct cmsghdr);
 		_debug("CMSG %d, %d, %d",
 		       cmsg->cmsg_level, cmsg->cmsg_type, len);

 		if (cmsg->cmsg_level != SOL_RXRPC)
 			continue;

 		switch (cmsg->cmsg_type) {
 		case RXRPC_USER_CALL_ID:
 			if (msg->msg_flags & MSG_CMSG_COMPAT) {
 				if (len != sizeof(u32))
 					return -EINVAL;
 				p->call.user_call_ID = *(u32 *)CMSG_DATA(cmsg);
 			} else {
 				if (len != sizeof(unsigned long))
 					return -EINVAL;
 				p->call.user_call_ID = *(unsigned long *)
 					CMSG_DATA(cmsg);
 			}
 			got_user_ID = true;
 			break;

 		case RXRPC_ABORT:
 			if (p->command != RXRPC_CMD_SEND_DATA)
 				return -EINVAL;
 			p->command = RXRPC_CMD_SEND_ABORT;
 			if (len != sizeof(p->abort_code))
 				return -EINVAL;
 			p->abort_code = *(unsigned int *)CMSG_DATA(cmsg);
 			if (p->abort_code == 0)
 				return -EINVAL;
 			break;

 		case RXRPC_ACCEPT:
 			if (p->command != RXRPC_CMD_SEND_DATA)
 				return -EINVAL;
 			p->command = RXRPC_CMD_ACCEPT;
 			if (len != 0)
 				return -EINVAL;
 			break;

 		case RXRPC_EXCLUSIVE_CALL:
 			p->exclusive = true;
 			if (len != 0)
 				return -EINVAL;
 			break;

 		case RXRPC_UPGRADE_SERVICE:
 			p->upgrade = true;
 			if (len != 0)
 				return -EINVAL;
 			break;

 		case RXRPC_TX_LENGTH:
 			if (p->call.tx_total_len != -1 || len != sizeof(__s64))
 				return -EINVAL;
 			p->call.tx_total_len = *(__s64 *)CMSG_DATA(cmsg);
 			if (p->call.tx_total_len < 0)
 				return -EINVAL;
 			break;

 		case RXRPC_SET_CALL_TIMEOUT:
 			if (len & 3 || len < 4 || len > 12)
 				return -EINVAL;
 			memcpy(&p->call.timeouts, CMSG_DATA(cmsg), len);
 			p->call.nr_timeouts = len / 4;
 			if (p->call.timeouts.hard > INT_MAX / HZ)
 				return -ERANGE;
 			if (p->call.nr_timeouts >= 2 && p->call.timeouts.idle > 60 * 60 * 1000)
 				return -ERANGE;
 			if (p->call.nr_timeouts >= 3 && p->call.timeouts.normal > 60 * 60 * 1000)
 				return -ERANGE;
 			break;

 		default:
 			return -EINVAL;
 		}
 	}

 	if (!got_user_ID)
 		return -EINVAL;
 	if (p->call.tx_total_len != -1 && p->command != RXRPC_CMD_SEND_DATA)
 		return -EINVAL;
 	_leave(" = 0");
 	return 0;
 }

 /*
  * Create a new client call for sendmsg().
  * - Called with the socket lock held, which it must release.
  * - If it returns a call, the call's lock will need releasing by the caller.
  */
 static struct rxrpc_call *
 rxrpc_new_client_call_for_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg,
 				  struct rxrpc_send_params *p)
 	__releases(&rx->sk.sk_lock.slock)
 	__acquires(&call->user_mutex)
 {
 	struct rxrpc_conn_parameters cp;
 	struct rxrpc_call *call;
 	struct key *key;

 	DECLARE_SOCKADDR(struct sockaddr_rxrpc *, srx, msg->msg_name);

 	_enter("");

 	if (!msg->msg_name) {
 		release_sock(&rx->sk);
 		return ERR_PTR(-EDESTADDRREQ);
 	}

 	key = rx->key;
 	if (key && !rx->key->payload.data[0])
 		key = NULL;

 	memset(&cp, 0, sizeof(cp));
 	cp.local		= rx->local;
 	cp.key			= rx->key;
 	cp.security_level	= rx->min_sec_level;
 	cp.exclusive		= rx->exclusive | p->exclusive;
 	cp.upgrade		= p->upgrade;
 	cp.service_id		= srx->srx_service;
 	call = rxrpc_new_client_call(rx, &cp, srx, &p->call, GFP_KERNEL,
 				     atomic_inc_return(&rxrpc_debug_id));
 	/* The socket is now unlocked */

 	rxrpc_put_peer(cp.peer);
 	_leave(" = %p\n", call);
 	return call;
 }

 /*
  * send a message forming part of a client call through an RxRPC socket
  * - caller holds the socket locked
  * - the socket may be either a client socket or a server socket
  */
 int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
 	__releases(&rx->sk.sk_lock.slock)
 	__releases(&call->user_mutex)
 {
 	enum rxrpc_call_state state;
 	struct rxrpc_call *call;
 	unsigned long now, j;
 	int ret;

 	struct rxrpc_send_params p = {
 		.call.tx_total_len	= -1,
 		.call.user_call_ID	= 0,
 		.call.nr_timeouts	= 0,
 		.call.intr		= true,
 		.abort_code		= 0,
 		.command		= RXRPC_CMD_SEND_DATA,
 		.exclusive		= false,
 		.upgrade		= false,
 	};

 	_enter("");

 	ret = rxrpc_sendmsg_cmsg(msg, &p);
 	if (ret < 0)
 		goto error_release_sock;

 	if (p.command == RXRPC_CMD_ACCEPT) {
 		ret = -EINVAL;
 		if (rx->sk.sk_state != RXRPC_SERVER_LISTENING)
 			goto error_release_sock;
 		call = rxrpc_accept_call(rx, p.call.user_call_ID, NULL);
 		/* The socket is now unlocked. */
 		if (IS_ERR(call))
 			return PTR_ERR(call);
 		ret = 0;
 		goto out_put_unlock;
 	}

 	call = rxrpc_find_call_by_user_ID(rx, p.call.user_call_ID);
 	if (!call) {
 		ret = -EBADSLT;
 		if (p.command != RXRPC_CMD_SEND_DATA)
 			goto error_release_sock;
 		call = rxrpc_new_client_call_for_sendmsg(rx, msg, &p);
 		/* The socket is now unlocked... */
 		if (IS_ERR(call))
 			return PTR_ERR(call);
 		/* ... and we have the call lock. */
 	} else {
 		switch (READ_ONCE(call->state)) {
 		case RXRPC_CALL_UNINITIALISED:
 		case RXRPC_CALL_CLIENT_AWAIT_CONN:
 		case RXRPC_CALL_SERVER_PREALLOC:
 		case RXRPC_CALL_SERVER_SECURING:
 		case RXRPC_CALL_SERVER_ACCEPTING:
 			rxrpc_put_call(call, rxrpc_call_put);
 			ret = -EBUSY;
 			goto error_release_sock;
 		default:
 			break;
 		}

 		ret = mutex_lock_interruptible(&call->user_mutex);
 		release_sock(&rx->sk);
 		if (ret < 0) {
 			ret = -ERESTARTSYS;
 			goto error_put;
 		}

 		if (p.call.tx_total_len != -1) {
 			ret = -EINVAL;
 			if (call->tx_total_len != -1 ||
 			    call->tx_pending ||
 			    call->tx_top != 0)
 				goto error_put;
 			call->tx_total_len = p.call.tx_total_len;
 		}
 	}

 	switch (p.call.nr_timeouts) {
 	case 3:
 		j = msecs_to_jiffies(p.call.timeouts.normal);
 		if (p.call.timeouts.normal > 0 && j == 0)
 			j = 1;
 		WRITE_ONCE(call->next_rx_timo, j);
 		/* Fall through */
 	case 2:
 		j = msecs_to_jiffies(p.call.timeouts.idle);
 		if (p.call.timeouts.idle > 0 && j == 0)
 			j = 1;
 		WRITE_ONCE(call->next_req_timo, j);
 		/* Fall through */
 	case 1:
 		if (p.call.timeouts.hard > 0) {
 			j = msecs_to_jiffies(p.call.timeouts.hard);
 			now = jiffies;
 			j += now;
 			WRITE_ONCE(call->expect_term_by, j);
 			rxrpc_reduce_call_timer(call, j, now,
 						rxrpc_timer_set_for_hard);
 		}
 		break;
 	}

 	state = READ_ONCE(call->state);
 	_debug("CALL %d USR %lx ST %d on CONN %p",
 	       call->debug_id, call->user_call_ID, state, call->conn);

 	if (state >= RXRPC_CALL_COMPLETE) {
 		/* it's too late for this call */
 		ret = -ESHUTDOWN;
 	} else if (p.command == RXRPC_CMD_SEND_ABORT) {
 		ret = 0;
 		if (rxrpc_abort_call("CMD", call, 0, p.abort_code, -ECONNABORTED))
 			ret = rxrpc_send_abort_packet(call);
 	} else if (p.command != RXRPC_CMD_SEND_DATA) {
 		ret = -EINVAL;
 	} else if (rxrpc_is_client_call(call) &&
 		   state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
 		/* request phase complete for this client call */
 		ret = -EPROTO;
 	} else if (rxrpc_is_service_call(call) &&
 		   state != RXRPC_CALL_SERVER_ACK_REQUEST &&
 		   state != RXRPC_CALL_SERVER_SEND_REPLY) {
 		/* Reply phase not begun or not complete for service call. */
 		ret = -EPROTO;
 	} else {
 		ret = rxrpc_send_data(rx, call, msg, len, NULL);
 	}

 out_put_unlock:
 	mutex_unlock(&call->user_mutex);
 error_put:
 	rxrpc_put_call(call, rxrpc_call_put);
 	_leave(" = %d", ret);
 	return ret;

 error_release_sock:
 	release_sock(&rx->sk);
 	return ret;
 }

 /**
  * rxrpc_kernel_send_data - Allow a kernel service to send data on a call
  * @sock: The socket the call is on
  * @call: The call to send data through
  * @msg: The data to send
  * @len: The amount of data to send
  * @notify_end_tx: Notification that the last packet is queued.
  *
  * Allow a kernel service to send data on a call.  The call must be in an state
  * appropriate to sending data.  No control data should be supplied in @msg,
  * nor should an address be supplied.  MSG_MORE should be flagged if there's
  * more data to come, otherwise this data will end the transmission phase.
  */
 int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call,
 			   struct msghdr *msg, size_t len,
 			   rxrpc_notify_end_tx_t notify_end_tx)
 {
 	int ret;

 	_enter("{%d,%s},", call->debug_id, rxrpc_call_states[call->state]);

 	ASSERTCMP(msg->msg_name, ==, NULL);
 	ASSERTCMP(msg->msg_control, ==, NULL);

 	mutex_lock(&call->user_mutex);

 	_debug("CALL %d USR %lx ST %d on CONN %p",
 	       call->debug_id, call->user_call_ID, call->state, call->conn);

 	switch (READ_ONCE(call->state)) {
 	case RXRPC_CALL_CLIENT_SEND_REQUEST:
 	case RXRPC_CALL_SERVER_ACK_REQUEST:
 	case RXRPC_CALL_SERVER_SEND_REPLY:
 		ret = rxrpc_send_data(rxrpc_sk(sock->sk), call, msg, len,
 				      notify_end_tx);
 		break;
 	case RXRPC_CALL_COMPLETE:
 		read_lock_bh(&call->state_lock);
 		ret = call->error;
 		read_unlock_bh(&call->state_lock);
 		break;
 	default:
 		/* Request phase complete for this client call */
 		trace_rxrpc_rx_eproto(call, 0, tracepoint_string("late_send"));
 		ret = -EPROTO;
 		break;
 	}

 	mutex_unlock(&call->user_mutex);
 	_leave(" = %d", ret);
 	return ret;
 }
 EXPORT_SYMBOL(rxrpc_kernel_send_data);

 /**
  * rxrpc_kernel_abort_call - Allow a kernel service to abort a call
  * @sock: The socket the call is on
  * @call: The call to be aborted
  * @abort_code: The abort code to stick into the ABORT packet
  * @error: Local error value
  * @why: 3-char string indicating why.
  *
  * Allow a kernel service to abort a call, if it's still in an abortable state
  * and return true if the call was aborted, false if it was already complete.
  */
 bool rxrpc_kernel_abort_call(struct socket *sock, struct rxrpc_call *call,
 			     u32 abort_code, int error, const char *why)
 {
 	bool aborted;

 	_enter("{%d},%d,%d,%s", call->debug_id, abort_code, error, why);

 	mutex_lock(&call->user_mutex);

 	aborted = rxrpc_abort_call(why, call, 0, abort_code, error);
 	if (aborted)
 		rxrpc_send_abort_packet(call);

 	mutex_unlock(&call->user_mutex);
 	return aborted;
 }
 EXPORT_SYMBOL(rxrpc_kernel_abort_call);

 /**
  * rxrpc_kernel_set_tx_length - Set the total Tx length on a call
  * @sock: The socket the call is on
  * @call: The call to be informed
  * @tx_total_len: The amount of data to be transmitted for this call
  *
  * Allow a kernel service to set the total transmit length on a call.  This
  * allows buffer-to-packet encrypt-and-copy to be performed.
  *
  * This function is primarily for use for setting the reply length since the
  * request length can be set when beginning the call.
  */
 void rxrpc_kernel_set_tx_length(struct socket *sock, struct rxrpc_call *call,
 				s64 tx_total_len)
 {
 	WARN_ON(call->tx_total_len != -1);
 	call->tx_total_len = tx_total_len;
 }
 EXPORT_SYMBOL(rxrpc_kernel_set_tx_length);
	// 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"

	/*
	* 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 (call->tx_top - call->tx_hard_ack <
	min_t(unsigned int, call->tx_winsize,
	call->cong_cwnd + call->cong_extra))
	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_nonintr(struct rxrpc_sock *rx,
	struct rxrpc_call *call)
	{
	rxrpc_seq_t tx_start, tx_win;
	signed long rtt2, timeout;
	u64 rtt;

	rtt = READ_ONCE(call->peer->rtt);
	rtt2 = nsecs_to_jiffies64(rtt) * 2;
	if (rtt2 < 1)
	rtt2 = 1;

	timeout = rtt2;
	tx_start = READ_ONCE(call->tx_hard_ack);

	for (;;) {
	set_current_state(TASK_UNINTERRUPTIBLE);

	tx_win = READ_ONCE(call->tx_hard_ack);
	if (call->tx_top - tx_win <
	min_t(unsigned int, call->tx_winsize,
	call->cong_cwnd + call->cong_extra))
	return 0;

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

	if (test_bit(RXRPC_CALL_IS_INTR, &call->flags) &&
	timeout == 0 &&
	tx_win == tx_start && signal_pending(current))
	return -EINTR;

	if (tx_win != tx_start) {
	timeout = rtt2;
	tx_start = tx_win;
	}

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

	/*
	* 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);

	if (waitall)
	ret = rxrpc_wait_for_tx_window_nonintr(rx, call);
	else
	ret = rxrpc_wait_for_tx_window_intr(rx, call, timeo);

	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, struct rxrpc_call call,
	rxrpc_notify_end_tx_t notify_end_tx)
	{
	if (notify_end_tx)
	notify_end_tx(&rx->sk, call, call->user_call_ID);
	}

	/*
	* Queue a DATA packet for transmission, set the resend timeout and send
	* the packet immediately. Returns the error from rxrpc_send_data_packet()
	* in case the caller wants to do something with it.
	*/
	static int rxrpc_queue_packet(struct rxrpc_sock rx, struct rxrpc_call call,
	struct sk_buff *skb, bool last,
	rxrpc_notify_end_tx_t notify_end_tx)
	{
	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
	unsigned long now;
	rxrpc_seq_t seq = sp->hdr.seq;
	int ret, ix;
	u8 annotation = RXRPC_TX_ANNO_UNACK;

	_net("queue skb %p [%d]", skb, seq);

	ASSERTCMP(seq, ==, call->tx_top + 1);

	if (last)
	annotation \|= RXRPC_TX_ANNO_LAST;

	/* We have to set the timestamp before queueing as the retransmit
	* algorithm can see the packet as soon as we queue it.
	*/
	skb->tstamp = ktime_get_real();

	ix = seq & RXRPC_RXTX_BUFF_MASK;
	rxrpc_get_skb(skb, rxrpc_skb_got);
	call->rxtx_annotations[ix] = annotation;
	smp_wmb();
	call->rxtx_buffer[ix] = skb;
	call->tx_top = seq;
	if (last)
	trace_rxrpc_transmit(call, rxrpc_transmit_queue_last);
	else
	trace_rxrpc_transmit(call, rxrpc_transmit_queue);

	if (last \|\| call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
	_debug("________awaiting reply/ACK__________");
	write_lock_bh(&call->state_lock);
	switch (call->state) {
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
	rxrpc_notify_end_tx(rx, call, notify_end_tx);
	break;
	case RXRPC_CALL_SERVER_ACK_REQUEST:
	call->state = RXRPC_CALL_SERVER_SEND_REPLY;
	now = jiffies;
	WRITE_ONCE(call->ack_at, now + MAX_JIFFY_OFFSET);
	if (call->ackr_reason == RXRPC_ACK_DELAY)
	call->ackr_reason = 0;
	trace_rxrpc_timer(call, rxrpc_timer_init_for_send_reply, now);
	if (!last)
	break;
	/* Fall through */
	case RXRPC_CALL_SERVER_SEND_REPLY:
	call->state = RXRPC_CALL_SERVER_AWAIT_ACK;
	rxrpc_notify_end_tx(rx, call, notify_end_tx);
	break;
	default:
	break;
	}
	write_unlock_bh(&call->state_lock);
	}

	if (seq == 1 && rxrpc_is_client_call(call))
	rxrpc_expose_client_call(call);

	ret = rxrpc_send_data_packet(call, skb, false);
	if (ret < 0) {
	switch (ret) {
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -ECONNREFUSED:
	rxrpc_set_call_completion(call,
	RXRPC_CALL_LOCAL_ERROR,
	0, ret);
	rxrpc_notify_socket(call);
	goto out;
	}
	_debug("need instant resend %d", ret);
	rxrpc_instant_resend(call, ix);
	} else {
	unsigned long now = jiffies, resend_at;

	if (call->peer->rtt_usage > 1)
	resend_at = nsecs_to_jiffies(call->peer->rtt * 3 / 2);
	else
	resend_at = rxrpc_resend_timeout;
	if (resend_at < 1)
	resend_at = 1;

	resend_at += now;
	WRITE_ONCE(call->resend_at, resend_at);
	rxrpc_reduce_call_timer(call, resend_at, now,
	rxrpc_timer_set_for_send);
	}

	out:
	rxrpc_free_skb(skb, rxrpc_skb_freed);
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* send data through a socket
	* - must be called in process context
	* - The caller holds the call user access mutex, but not the socket lock.
	*/
	static int rxrpc_send_data(struct rxrpc_sock *rx,
	struct rxrpc_call *call,
	struct msghdr *msg, size_t len,
	rxrpc_notify_end_tx_t notify_end_tx)
	{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	struct sock *sk = &rx->sk;
	long timeo;
	bool more;
	int ret, copied;

	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);

	/* this should be in poll */
	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);

	if (sk->sk_err \|\| (sk->sk_shutdown & SEND_SHUTDOWN))
	return -EPIPE;

	more = msg->msg_flags & MSG_MORE;

	if (call->tx_total_len != -1) {
	if (len > call->tx_total_len)
	return -EMSGSIZE;
	if (!more && len != call->tx_total_len)
	return -EMSGSIZE;
	}

	skb = call->tx_pending;
	call->tx_pending = NULL;
	rxrpc_see_skb(skb, rxrpc_skb_seen);

	copied = 0;
	do {
	/* Check to see if there's a ping ACK to reply to. */
	if (call->ackr_reason == RXRPC_ACK_PING_RESPONSE)
	rxrpc_send_ack_packet(call, false, NULL);

	if (!skb) {
	size_t size, chunk, max, space;

	_debug("alloc");

	if (call->tx_top - call->tx_hard_ack >=
	min_t(unsigned int, call->tx_winsize,
	call->cong_cwnd + call->cong_extra)) {
	ret = -EAGAIN;
	if (msg->msg_flags & MSG_DONTWAIT)
	goto maybe_error;
	ret = rxrpc_wait_for_tx_window(rx, call,
	&timeo,
	msg->msg_flags & MSG_WAITALL);
	if (ret < 0)
	goto maybe_error;
	}

	max = RXRPC_JUMBO_DATALEN;
	max -= call->conn->security_size;
	max &= ~(call->conn->size_align - 1UL);

	chunk = max;
	if (chunk > msg_data_left(msg) && !more)
	chunk = msg_data_left(msg);

	space = chunk + call->conn->size_align;
	space &= ~(call->conn->size_align - 1UL);

	size = space + call->conn->security_size;

	_debug("SIZE: %zu/%zu/%zu", chunk, space, size);

	/* create a buffer that we can retain until it's ACK'd */
	skb = sock_alloc_send_skb(
	sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
	if (!skb)
	goto maybe_error;

	sp = rxrpc_skb(skb);
	sp->rx_flags \|= RXRPC_SKB_TX_BUFFER;
	rxrpc_new_skb(skb, rxrpc_skb_new);

	_debug("ALLOC SEND %p", skb);

	ASSERTCMP(skb->mark, ==, 0);

	_debug("HS: %u", call->conn->security_size);
	skb_reserve(skb, call->conn->security_size);
	skb->len += call->conn->security_size;

	sp->remain = chunk;
	if (sp->remain > skb_tailroom(skb))
	sp->remain = skb_tailroom(skb);

	_net("skb: hr %d, tr %d, hl %d, rm %d",
	skb_headroom(skb),
	skb_tailroom(skb),
	skb_headlen(skb),
	sp->remain);

	skb->ip_summed = CHECKSUM_UNNECESSARY;
	}

	_debug("append");
	sp = rxrpc_skb(skb);

	/* append next segment of data to the current buffer */
	if (msg_data_left(msg) > 0) {
	int copy = skb_tailroom(skb);
	ASSERTCMP(copy, >, 0);
	if (copy > msg_data_left(msg))
	copy = msg_data_left(msg);
	if (copy > sp->remain)
	copy = sp->remain;

	_debug("add");
	ret = skb_add_data(skb, &msg->msg_iter, copy);
	_debug("added");
	if (ret < 0)
	goto efault;
	sp->remain -= copy;
	skb->mark += copy;
	copied += copy;
	if (call->tx_total_len != -1)
	call->tx_total_len -= copy;
	}

	/* check for the far side aborting the call or a network error
	* occurring */
	if (call->state == RXRPC_CALL_COMPLETE)
	goto call_terminated;

	/* add the packet to the send queue if it's now full */
	if (sp->remain <= 0 \|\|
	(msg_data_left(msg) == 0 && !more)) {
	struct rxrpc_connection *conn = call->conn;
	uint32_t seq;
	size_t pad;

	/* pad out if we're using security */
	if (conn->security_ix) {
	pad = conn->security_size + skb->mark;
	pad = conn->size_align - pad;
	pad &= conn->size_align - 1;
	_debug("pad %zu", pad);
	if (pad)
	skb_put_zero(skb, pad);
	}

	seq = call->tx_top + 1;

	sp->hdr.seq = seq;
	sp->hdr._rsvd = 0;
	sp->hdr.flags = conn->out_clientflag;

	if (msg_data_left(msg) == 0 && !more)
	sp->hdr.flags \|= RXRPC_LAST_PACKET;
	else if (call->tx_top - call->tx_hard_ack <
	call->tx_winsize)
	sp->hdr.flags \|= RXRPC_MORE_PACKETS;

	ret = call->security->secure_packet(
	call, skb, skb->mark, skb->head);
	if (ret < 0)
	goto out;

	ret = rxrpc_queue_packet(rx, call, skb,
	!msg_data_left(msg) && !more,
	notify_end_tx);
	/* Should check for failure here */
	skb = NULL;
	}
	} while (msg_data_left(msg) > 0);

	success:
	ret = copied;
	out:
	call->tx_pending = skb;
	_leave(" = %d", ret);
	return ret;

	call_terminated:
	rxrpc_free_skb(skb, rxrpc_skb_freed);
	_leave(" = %d", call->error);
	return call->error;

	maybe_error:
	if (copied)
	goto success;
	goto out;

	efault:
	ret = -EFAULT;
	goto out;
	}

	/*
	* extract control messages from the sendmsg() control buffer
	*/
	static int rxrpc_sendmsg_cmsg(struct msghdr msg, struct rxrpc_send_params p)
	{
	struct cmsghdr *cmsg;
	bool got_user_ID = false;
	int len;

	if (msg->msg_controllen == 0)
	return -EINVAL;

	for_each_cmsghdr(cmsg, msg) {
	if (!CMSG_OK(msg, cmsg))
	return -EINVAL;

	len = cmsg->cmsg_len - sizeof(struct cmsghdr);
	_debug("CMSG %d, %d, %d",
	cmsg->cmsg_level, cmsg->cmsg_type, len);

	if (cmsg->cmsg_level != SOL_RXRPC)
	continue;

	switch (cmsg->cmsg_type) {
	case RXRPC_USER_CALL_ID:
	if (msg->msg_flags & MSG_CMSG_COMPAT) {
	if (len != sizeof(u32))
	return -EINVAL;
	p->call.user_call_ID = (u32 )CMSG_DATA(cmsg);
	} else {
	if (len != sizeof(unsigned long))
	return -EINVAL;
	p->call.user_call_ID = (unsigned long )
	CMSG_DATA(cmsg);
	}
	got_user_ID = true;
	break;

	case RXRPC_ABORT:
	if (p->command != RXRPC_CMD_SEND_DATA)
	return -EINVAL;
	p->command = RXRPC_CMD_SEND_ABORT;
	if (len != sizeof(p->abort_code))
	return -EINVAL;
	p->abort_code = (unsigned int )CMSG_DATA(cmsg);
	if (p->abort_code == 0)
	return -EINVAL;
	break;

	case RXRPC_ACCEPT:
	if (p->command != RXRPC_CMD_SEND_DATA)
	return -EINVAL;
	p->command = RXRPC_CMD_ACCEPT;
	if (len != 0)
	return -EINVAL;
	break;

	case RXRPC_EXCLUSIVE_CALL:
	p->exclusive = true;
	if (len != 0)
	return -EINVAL;
	break;

	case RXRPC_UPGRADE_SERVICE:
	p->upgrade = true;
	if (len != 0)
	return -EINVAL;
	break;

	case RXRPC_TX_LENGTH:
	if (p->call.tx_total_len != -1 \|\| len != sizeof(__s64))
	return -EINVAL;
	p->call.tx_total_len = (__s64 )CMSG_DATA(cmsg);
	if (p->call.tx_total_len < 0)
	return -EINVAL;
	break;

	case RXRPC_SET_CALL_TIMEOUT:
	if (len & 3 \|\| len < 4 \|\| len > 12)
	return -EINVAL;
	memcpy(&p->call.timeouts, CMSG_DATA(cmsg), len);
	p->call.nr_timeouts = len / 4;
	if (p->call.timeouts.hard > INT_MAX / HZ)
	return -ERANGE;
	if (p->call.nr_timeouts >= 2 && p->call.timeouts.idle > 60 * 60 * 1000)
	return -ERANGE;
	if (p->call.nr_timeouts >= 3 && p->call.timeouts.normal > 60 * 60 * 1000)
	return -ERANGE;
	break;

	default:
	return -EINVAL;
	}
	}

	if (!got_user_ID)
	return -EINVAL;
	if (p->call.tx_total_len != -1 && p->command != RXRPC_CMD_SEND_DATA)
	return -EINVAL;
	_leave(" = 0");
	return 0;
	}

	/*
	* Create a new client call for sendmsg().
	* - Called with the socket lock held, which it must release.
	* - If it returns a call, the call's lock will need releasing by the caller.
	*/
	static struct rxrpc_call *
	rxrpc_new_client_call_for_sendmsg(struct rxrpc_sock rx, struct msghdr msg,
	struct rxrpc_send_params *p)
	__releases(&rx->sk.sk_lock.slock)
	__acquires(&call->user_mutex)
	{
	struct rxrpc_conn_parameters cp;
	struct rxrpc_call *call;
	struct key *key;

	DECLARE_SOCKADDR(struct sockaddr_rxrpc *, srx, msg->msg_name);

	_enter("");

	if (!msg->msg_name) {
	release_sock(&rx->sk);
	return ERR_PTR(-EDESTADDRREQ);
	}

	key = rx->key;
	if (key && !rx->key->payload.data[0])
	key = NULL;

	memset(&cp, 0, sizeof(cp));
	cp.local = rx->local;
	cp.key = rx->key;
	cp.security_level = rx->min_sec_level;
	cp.exclusive = rx->exclusive \| p->exclusive;
	cp.upgrade = p->upgrade;
	cp.service_id = srx->srx_service;
	call = rxrpc_new_client_call(rx, &cp, srx, &p->call, GFP_KERNEL,
	atomic_inc_return(&rxrpc_debug_id));
	/* The socket is now unlocked */

	rxrpc_put_peer(cp.peer);
	_leave(" = %p\n", call);
	return call;
	}

	/*
	* send a message forming part of a client call through an RxRPC socket
	* - caller holds the socket locked
	* - the socket may be either a client socket or a server socket
	*/
	int rxrpc_do_sendmsg(struct rxrpc_sock rx, struct msghdr msg, size_t len)
	__releases(&rx->sk.sk_lock.slock)
	__releases(&call->user_mutex)
	{
	enum rxrpc_call_state state;
	struct rxrpc_call *call;
	unsigned long now, j;
	int ret;

	struct rxrpc_send_params p = {
	.call.tx_total_len = -1,
	.call.user_call_ID = 0,
	.call.nr_timeouts = 0,
	.call.intr = true,
	.abort_code = 0,
	.command = RXRPC_CMD_SEND_DATA,
	.exclusive = false,
	.upgrade = false,
	};

	_enter("");

	ret = rxrpc_sendmsg_cmsg(msg, &p);
	if (ret < 0)
	goto error_release_sock;

	if (p.command == RXRPC_CMD_ACCEPT) {
	ret = -EINVAL;
	if (rx->sk.sk_state != RXRPC_SERVER_LISTENING)
	goto error_release_sock;
	call = rxrpc_accept_call(rx, p.call.user_call_ID, NULL);
	/* The socket is now unlocked. */
	if (IS_ERR(call))
	return PTR_ERR(call);
	ret = 0;
	goto out_put_unlock;
	}

	call = rxrpc_find_call_by_user_ID(rx, p.call.user_call_ID);
	if (!call) {
	ret = -EBADSLT;
	if (p.command != RXRPC_CMD_SEND_DATA)
	goto error_release_sock;
	call = rxrpc_new_client_call_for_sendmsg(rx, msg, &p);
	/* The socket is now unlocked... */
	if (IS_ERR(call))
	return PTR_ERR(call);
	/* ... and we have the call lock. */
	} else {
	switch (READ_ONCE(call->state)) {
	case RXRPC_CALL_UNINITIALISED:
	case RXRPC_CALL_CLIENT_AWAIT_CONN:
	case RXRPC_CALL_SERVER_PREALLOC:
	case RXRPC_CALL_SERVER_SECURING:
	case RXRPC_CALL_SERVER_ACCEPTING:
	rxrpc_put_call(call, rxrpc_call_put);
	ret = -EBUSY;
	goto error_release_sock;
	default:
	break;
	}

	ret = mutex_lock_interruptible(&call->user_mutex);
	release_sock(&rx->sk);
	if (ret < 0) {
	ret = -ERESTARTSYS;
	goto error_put;
	}

	if (p.call.tx_total_len != -1) {
	ret = -EINVAL;
	if (call->tx_total_len != -1 \|\|
	call->tx_pending \|\|
	call->tx_top != 0)
	goto error_put;
	call->tx_total_len = p.call.tx_total_len;
	}
	}

	switch (p.call.nr_timeouts) {
	case 3:
	j = msecs_to_jiffies(p.call.timeouts.normal);
	if (p.call.timeouts.normal > 0 && j == 0)
	j = 1;
	WRITE_ONCE(call->next_rx_timo, j);
	/* Fall through */
	case 2:
	j = msecs_to_jiffies(p.call.timeouts.idle);
	if (p.call.timeouts.idle > 0 && j == 0)
	j = 1;
	WRITE_ONCE(call->next_req_timo, j);
	/* Fall through */
	case 1:
	if (p.call.timeouts.hard > 0) {
	j = msecs_to_jiffies(p.call.timeouts.hard);
	now = jiffies;
	j += now;
	WRITE_ONCE(call->expect_term_by, j);
	rxrpc_reduce_call_timer(call, j, now,
	rxrpc_timer_set_for_hard);
	}
	break;
	}

	state = READ_ONCE(call->state);
	_debug("CALL %d USR %lx ST %d on CONN %p",
	call->debug_id, call->user_call_ID, state, call->conn);

	if (state >= RXRPC_CALL_COMPLETE) {
	/* it's too late for this call */
	ret = -ESHUTDOWN;
	} else if (p.command == RXRPC_CMD_SEND_ABORT) {
	ret = 0;
	if (rxrpc_abort_call("CMD", call, 0, p.abort_code, -ECONNABORTED))
	ret = rxrpc_send_abort_packet(call);
	} else if (p.command != RXRPC_CMD_SEND_DATA) {
	ret = -EINVAL;
	} else if (rxrpc_is_client_call(call) &&
	state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
	/* request phase complete for this client call */
	ret = -EPROTO;
	} else if (rxrpc_is_service_call(call) &&
	state != RXRPC_CALL_SERVER_ACK_REQUEST &&
	state != RXRPC_CALL_SERVER_SEND_REPLY) {
	/* Reply phase not begun or not complete for service call. */
	ret = -EPROTO;
	} else {
	ret = rxrpc_send_data(rx, call, msg, len, NULL);
	}

	out_put_unlock:
	mutex_unlock(&call->user_mutex);
	error_put:
	rxrpc_put_call(call, rxrpc_call_put);
	_leave(" = %d", ret);
	return ret;

	error_release_sock:
	release_sock(&rx->sk);
	return ret;
	}

	/**
	* rxrpc_kernel_send_data - Allow a kernel service to send data on a call
	* @sock: The socket the call is on
	* @call: The call to send data through
	* @msg: The data to send
	* @len: The amount of data to send
	* @notify_end_tx: Notification that the last packet is queued.
	*
	* Allow a kernel service to send data on a call. The call must be in an state
	* appropriate to sending data. No control data should be supplied in @msg,
	* nor should an address be supplied. MSG_MORE should be flagged if there's
	* more data to come, otherwise this data will end the transmission phase.
	*/
	int rxrpc_kernel_send_data(struct socket sock, struct rxrpc_call call,
	struct msghdr *msg, size_t len,
	rxrpc_notify_end_tx_t notify_end_tx)
	{
	int ret;

	_enter("{%d,%s},", call->debug_id, rxrpc_call_states[call->state]);

	ASSERTCMP(msg->msg_name, ==, NULL);
	ASSERTCMP(msg->msg_control, ==, NULL);

	mutex_lock(&call->user_mutex);

	_debug("CALL %d USR %lx ST %d on CONN %p",
	call->debug_id, call->user_call_ID, call->state, call->conn);

	switch (READ_ONCE(call->state)) {
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	case RXRPC_CALL_SERVER_ACK_REQUEST:
	case RXRPC_CALL_SERVER_SEND_REPLY:
	ret = rxrpc_send_data(rxrpc_sk(sock->sk), call, msg, len,
	notify_end_tx);
	break;
	case RXRPC_CALL_COMPLETE:
	read_lock_bh(&call->state_lock);
	ret = call->error;
	read_unlock_bh(&call->state_lock);
	break;
	default:
	/* Request phase complete for this client call */
	trace_rxrpc_rx_eproto(call, 0, tracepoint_string("late_send"));
	ret = -EPROTO;
	break;
	}

	mutex_unlock(&call->user_mutex);
	_leave(" = %d", ret);
	return ret;
	}
	EXPORT_SYMBOL(rxrpc_kernel_send_data);

	/**
	* rxrpc_kernel_abort_call - Allow a kernel service to abort a call
	* @sock: The socket the call is on
	* @call: The call to be aborted
	* @abort_code: The abort code to stick into the ABORT packet
	* @error: Local error value
	* @why: 3-char string indicating why.
	*
	* Allow a kernel service to abort a call, if it's still in an abortable state
	* and return true if the call was aborted, false if it was already complete.
	*/
	bool rxrpc_kernel_abort_call(struct socket sock, struct rxrpc_call call,
	u32 abort_code, int error, const char *why)
	{
	bool aborted;

	_enter("{%d},%d,%d,%s", call->debug_id, abort_code, error, why);

	mutex_lock(&call->user_mutex);

	aborted = rxrpc_abort_call(why, call, 0, abort_code, error);
	if (aborted)
	rxrpc_send_abort_packet(call);

	mutex_unlock(&call->user_mutex);
	return aborted;
	}
	EXPORT_SYMBOL(rxrpc_kernel_abort_call);

	/**
	* rxrpc_kernel_set_tx_length - Set the total Tx length on a call
	* @sock: The socket the call is on
	* @call: The call to be informed
	* @tx_total_len: The amount of data to be transmitted for this call
	*
	* Allow a kernel service to set the total transmit length on a call. This
	* allows buffer-to-packet encrypt-and-copy to be performed.
	*
	* This function is primarily for use for setting the reply length since the
	* request length can be set when beginning the call.
	*/
	void rxrpc_kernel_set_tx_length(struct socket sock, struct rxrpc_call call,
	s64 tx_total_len)
	{
	WARN_ON(call->tx_total_len != -1);
	call->tx_total_len = tx_total_len;
	}
	EXPORT_SYMBOL(rxrpc_kernel_set_tx_length);