xref: /linux/fs/smb/smbdirect/accept.c (revision 0fc8f6200d2313278fbf4539bbab74677c685531)

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Copyright (C) 2017, Microsoft Corporation.
 *   Copyright (C) 2018, LG Electronics.
 *   Copyright (c) 2025, Stefan Metzmacher
 */

#include "internal.h"
#include <net/sock.h>
#include "../common/smb2status.h"

static int smbdirect_accept_rdma_event_handler(struct rdma_cm_id *id,
					       struct rdma_cm_event *event);
static int smbdirect_accept_init_params(struct smbdirect_socket *sc);
static void smbdirect_accept_negotiate_recv_done(struct ib_cq *cq, struct ib_wc *wc);
static void smbdirect_accept_negotiate_send_done(struct ib_cq *cq, struct ib_wc *wc);

int smbdirect_accept_connect_request(struct smbdirect_socket *sc,
				     const struct rdma_conn_param *param)
{
	struct smbdirect_socket_parameters *sp = &sc->parameters;
	struct smbdirect_recv_io *recv_io;
	u8 peer_initiator_depth;
	u8 peer_responder_resources;
	struct rdma_conn_param conn_param;
	__be32 ird_ord_hdr[2];
	int ret;

	if (SMBDIRECT_CHECK_STATUS_WARN(sc, SMBDIRECT_SOCKET_CREATED))
		return -EINVAL;

	/*
	 * First set what the we as server are able to support
	 */
	sp->initiator_depth = min_t(u8, sp->initiator_depth,
				    sc->ib.dev->attrs.max_qp_rd_atom);

	peer_initiator_depth = param->initiator_depth;
	peer_responder_resources = param->responder_resources;
	smbdirect_connection_negotiate_rdma_resources(sc,
						      peer_initiator_depth,
						      peer_responder_resources,
						      param);

	ret = smbdirect_accept_init_params(sc);
	if (ret) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_accept_init_params() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		goto init_params_failed;
	}

	ret = smbdirect_connection_create_qp(sc);
	if (ret) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_create_qp() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		goto create_qp_failed;
	}

	ret = smbdirect_connection_create_mem_pools(sc);
	if (ret) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_create_mem_pools() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		goto create_mem_failed;
	}

	recv_io = smbdirect_connection_get_recv_io(sc);
	if (WARN_ON_ONCE(!recv_io)) {
		ret = -EINVAL;
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_get_recv_io() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		goto get_recv_io_failed;
	}
	recv_io->cqe.done = smbdirect_accept_negotiate_recv_done;

	/*
	 * Now post the recv_io buffer in order to get
	 * the negotiate request
	 */
	sc->recv_io.expected = SMBDIRECT_EXPECT_NEGOTIATE_REQ;
	ret = smbdirect_connection_post_recv_io(recv_io);
	if (ret) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_post_recv_io() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		goto post_recv_io_failed;
	}
	/*
	 * From here recv_io is known to the RDMA QP and needs ib_drain_qp and
	 * smbdirect_accept_negotiate_recv_done to cleanup...
	 */
	recv_io = NULL;

	/* already checked with SMBDIRECT_CHECK_STATUS_WARN above */
	WARN_ON_ONCE(sc->status != SMBDIRECT_SOCKET_CREATED);
	sc->status = SMBDIRECT_SOCKET_RDMA_CONNECT_NEEDED;

	/*
	 * We already negotiated sp->initiator_depth
	 * and sp->responder_resources above.
	 */
	memset(&conn_param, 0, sizeof(conn_param));
	conn_param.initiator_depth = sp->initiator_depth;
	conn_param.responder_resources = sp->responder_resources;

	if (sc->rdma.legacy_iwarp) {
		ird_ord_hdr[0] = cpu_to_be32(conn_param.responder_resources);
		ird_ord_hdr[1] = cpu_to_be32(conn_param.initiator_depth);
		conn_param.private_data = ird_ord_hdr;
		conn_param.private_data_len = sizeof(ird_ord_hdr);
	} else {
		conn_param.private_data = NULL;
		conn_param.private_data_len = 0;
	}
	conn_param.retry_count = SMBDIRECT_RDMA_CM_RETRY;
	conn_param.rnr_retry_count = SMBDIRECT_RDMA_CM_RNR_RETRY;
	conn_param.flow_control = 0;

	/* explicitly set above */
	WARN_ON_ONCE(sc->status != SMBDIRECT_SOCKET_RDMA_CONNECT_NEEDED);
	sc->status = SMBDIRECT_SOCKET_RDMA_CONNECT_RUNNING;
	sc->rdma.expected_event = RDMA_CM_EVENT_ESTABLISHED;
	sc->rdma.cm_id->event_handler = smbdirect_accept_rdma_event_handler;
	ret = rdma_accept(sc->rdma.cm_id, &conn_param);
	if (ret) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"rdma_accept() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		goto rdma_accept_failed;
	}

	/*
	 * start with the negotiate timeout and SMBDIRECT_KEEPALIVE_PENDING
	 * so that the timer will cause a disconnect.
	 */
	INIT_DELAYED_WORK(&sc->idle.timer_work, smbdirect_connection_idle_timer_work);
	sc->idle.keepalive = SMBDIRECT_KEEPALIVE_PENDING;
	mod_delayed_work(sc->workqueues.idle, &sc->idle.timer_work,
			 msecs_to_jiffies(sp->negotiate_timeout_msec));

	return 0;

rdma_accept_failed:
	/*
	 * smbdirect_connection_destroy_qp() calls ib_drain_qp(),
	 * so that smbdirect_accept_negotiate_recv_done() will
	 * call smbdirect_connection_put_recv_io()
	 */
post_recv_io_failed:
	if (recv_io)
		smbdirect_connection_put_recv_io(recv_io);
get_recv_io_failed:
	smbdirect_connection_destroy_mem_pools(sc);
create_mem_failed:
	smbdirect_connection_destroy_qp(sc);
create_qp_failed:
init_params_failed:
	return ret;
}

static int smbdirect_accept_init_params(struct smbdirect_socket *sc)
{
	const struct smbdirect_socket_parameters *sp = &sc->parameters;
	int max_send_sges;
	unsigned int maxpages;

	/* need 3 more sge. because a SMB_DIRECT header, SMB2 header,
	 * SMB2 response could be mapped.
	 */
	max_send_sges = DIV_ROUND_UP(sp->max_send_size, PAGE_SIZE) + 3;
	if (max_send_sges > SMBDIRECT_SEND_IO_MAX_SGE) {
		pr_err("max_send_size %d is too large\n", sp->max_send_size);
		return -EINVAL;
	}

	/*
	 * There is only a single batch credit
	 */
	atomic_set(&sc->send_io.bcredits.count, 1);

	/*
	 * Initialize the local credits to post
	 * IB_WR_SEND[_WITH_INV].
	 */
	atomic_set(&sc->send_io.lcredits.count, sp->send_credit_target);

	if (sp->max_read_write_size) {
		maxpages = DIV_ROUND_UP(sp->max_read_write_size, PAGE_SIZE);
		sc->rw_io.credits.max = rdma_rw_mr_factor(sc->ib.dev,
							  sc->rdma.cm_id->port_num,
							  maxpages);
		sc->rw_io.credits.num_pages = DIV_ROUND_UP(maxpages, sc->rw_io.credits.max);
		/* add one extra in order to handle unaligned pages */
		sc->rw_io.credits.max += 1;
	}

	sc->recv_io.credits.target = 1;

	atomic_set(&sc->rw_io.credits.count, sc->rw_io.credits.max);

	return 0;
}

static void smbdirect_accept_negotiate_recv_work(struct work_struct *work);

static void smbdirect_accept_negotiate_recv_done(struct ib_cq *cq, struct ib_wc *wc)
{
	struct smbdirect_recv_io *recv_io =
		container_of(wc->wr_cqe, struct smbdirect_recv_io, cqe);
	struct smbdirect_socket *sc = recv_io->socket;
	unsigned long flags;

	if (unlikely(wc->status != IB_WC_SUCCESS || WARN_ON_ONCE(wc->opcode != IB_WC_RECV))) {
		if (wc->status != IB_WC_WR_FLUSH_ERR)
			smbdirect_log_rdma_recv(sc, SMBDIRECT_LOG_ERR,
				"wc->status=%s (%d) wc->opcode=%d\n",
				ib_wc_status_msg(wc->status), wc->status, wc->opcode);
		goto error;
	}

	smbdirect_log_rdma_recv(sc, SMBDIRECT_LOG_INFO,
		"smbdirect_recv_io completed. status='%s (%d)', opcode=%d\n",
		ib_wc_status_msg(wc->status), wc->status, wc->opcode);

	/*
	 * This is an internal error!
	 */
	if (WARN_ON_ONCE(sc->recv_io.expected != SMBDIRECT_EXPECT_NEGOTIATE_REQ))
		goto error;

	/*
	 * Don't reset timer to the keepalive interval in
	 * this will be done in smbdirect_accept_direct_negotiate_recv_work.
	 */

	ib_dma_sync_single_for_cpu(sc->ib.dev,
				   recv_io->sge.addr,
				   recv_io->sge.length,
				   DMA_FROM_DEVICE);

	/*
	 * Only remember recv_io if it has enough bytes,
	 * this gives smbdirect_accept_negotiate_recv_work enough
	 * information in order to disconnect if it was not
	 * valid.
	 */
	sc->recv_io.reassembly.full_packet_received = true;
	if (wc->byte_len >= sizeof(struct smbdirect_negotiate_req))
		smbdirect_connection_reassembly_append_recv_io(sc, recv_io, 0);
	else
		smbdirect_connection_put_recv_io(recv_io);

	/*
	 * Some drivers (at least mlx5_ib and irdma) might post a
	 * recv completion before RDMA_CM_EVENT_ESTABLISHED,
	 * we need to adjust our expectation in that case.
	 *
	 * So we defer further processing of the negotiation
	 * to smbdirect_accept_negotiate_recv_work().
	 *
	 * If we are already in SMBDIRECT_SOCKET_NEGOTIATE_NEEDED
	 * we queue the work directly otherwise
	 * smbdirect_accept_rdma_event_handler() will do it, when
	 * RDMA_CM_EVENT_ESTABLISHED arrived.
	 */
	spin_lock_irqsave(&sc->connect.lock, flags);
	if (!sc->first_error) {
		INIT_WORK(&sc->connect.work, smbdirect_accept_negotiate_recv_work);
		if (sc->status == SMBDIRECT_SOCKET_NEGOTIATE_NEEDED)
			queue_work(sc->workqueues.accept, &sc->connect.work);
	}
	spin_unlock_irqrestore(&sc->connect.lock, flags);

	return;

error:
	/*
	 * recv_io.posted.refill_work is still disabled,
	 * so smbdirect_connection_put_recv_io() won't
	 * start it.
	 */
	smbdirect_connection_put_recv_io(recv_io);
	smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
}

static void smbdirect_accept_negotiate_recv_work(struct work_struct *work)
{
	struct smbdirect_socket *sc =
		container_of(work, struct smbdirect_socket, connect.work);
	struct smbdirect_socket_parameters *sp = &sc->parameters;
	struct smbdirect_recv_io *recv_io;
	struct smbdirect_negotiate_req *nreq;
	unsigned long flags;
	u16 min_version;
	u16 max_version;
	u16 credits_requested;
	u32 preferred_send_size;
	u32 max_receive_size;
	u32 max_fragmented_size;
	u32 ntstatus;

	if (sc->first_error)
		return;

	/*
	 * make sure we won't start again...
	 */
	disable_work(work);

	/*
	 * Reset timer to the keepalive interval in
	 * order to trigger our next keepalive message.
	 */
	sc->idle.keepalive = SMBDIRECT_KEEPALIVE_NONE;
	mod_delayed_work(sc->workqueues.idle, &sc->idle.timer_work,
			 msecs_to_jiffies(sp->keepalive_interval_msec));

	/*
	 * If smbdirect_accept_negotiate_recv_done() detected an
	 * invalid request we want to disconnect.
	 */
	recv_io = smbdirect_connection_reassembly_first_recv_io(sc);
	if (!recv_io) {
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
		return;
	}
	spin_lock_irqsave(&sc->recv_io.reassembly.lock, flags);
	sc->recv_io.reassembly.queue_length--;
	list_del(&recv_io->list);
	spin_unlock_irqrestore(&sc->recv_io.reassembly.lock, flags);
	smbdirect_connection_put_recv_io(recv_io);

	if (SMBDIRECT_CHECK_STATUS_DISCONNECT(sc, SMBDIRECT_SOCKET_NEGOTIATE_NEEDED))
		return;
	sc->status = SMBDIRECT_SOCKET_NEGOTIATE_RUNNING;

	/*
	 * Note recv_io is already part of the free list,
	 * as we just called smbdirect_connection_put_recv_io(),
	 * but it won't be reused before we call
	 * smbdirect_connection_recv_io_refill() below.
	 */

	nreq = (struct smbdirect_negotiate_req *)recv_io->packet;
	min_version = le16_to_cpu(nreq->min_version);
	max_version = le16_to_cpu(nreq->max_version);
	credits_requested = le16_to_cpu(nreq->credits_requested);
	preferred_send_size = le32_to_cpu(nreq->preferred_send_size);
	max_receive_size = le32_to_cpu(nreq->max_receive_size);
	max_fragmented_size = le32_to_cpu(nreq->max_fragmented_size);

	smbdirect_log_negotiate(sc, SMBDIRECT_LOG_INFO,
		"ReqIn: %s%x, %s%x, %s%u, %s%u, %s%u, %s%u\n",
		"MinVersion=0x",
		le16_to_cpu(nreq->min_version),
		"MaxVersion=0x",
		le16_to_cpu(nreq->max_version),
		"CreditsRequested=",
		le16_to_cpu(nreq->credits_requested),
		"PreferredSendSize=",
		le32_to_cpu(nreq->preferred_send_size),
		"MaxRecvSize=",
		le32_to_cpu(nreq->max_receive_size),
		"MaxFragmentedSize=",
		le32_to_cpu(nreq->max_fragmented_size));

	if (!(min_version <= SMBDIRECT_V1 && max_version >= SMBDIRECT_V1)) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"invalid: min_version=0x%x max_version=0x%x\n",
			min_version, max_version);
		ntstatus = le32_to_cpu(STATUS_NOT_SUPPORTED);
		goto not_supported;
	}

	if (credits_requested == 0) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"invalid: credits_requested == 0\n");
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
		return;
	}

	if (max_receive_size < SMBDIRECT_MIN_RECEIVE_SIZE) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"invalid: max_receive_size=%u < %u\n",
			max_receive_size,
			SMBDIRECT_MIN_RECEIVE_SIZE);
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
		return;
	}

	if (max_fragmented_size < SMBDIRECT_MIN_FRAGMENTED_SIZE) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"invalid: max_fragmented_size=%u < %u\n",
			max_fragmented_size,
			SMBDIRECT_MIN_FRAGMENTED_SIZE);
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
		return;
	}

	/*
	 * At least the value of SMBDIRECT_MIN_RECEIVE_SIZE is used.
	 */
	sp->max_recv_size = min_t(u32, sp->max_recv_size, preferred_send_size);
	sp->max_recv_size = max_t(u32, sp->max_recv_size, SMBDIRECT_MIN_RECEIVE_SIZE);

	/*
	 * The maximum fragmented upper-layer payload receive size supported
	 *
	 * Assume max_payload_per_credit is
	 * smb_direct_receive_credit_max - 24 = 1340
	 *
	 * The maximum number would be
	 * smb_direct_receive_credit_max * max_payload_per_credit
	 *
	 *                       1340 * 255 = 341700 (0x536C4)
	 *
	 * The minimum value from the spec is 131072 (0x20000)
	 *
	 * For now we use the logic we used in ksmbd before:
	 *                 (1364 * 255) / 2 = 173910 (0x2A756)
	 *
	 * We need to adjust this here in case the peer
	 * lowered sp->max_recv_size.
	 *
	 * TODO: instead of adjusting max_fragmented_recv_size
	 * we should adjust the number of available buffers,
	 * but for now we keep the logic as it was used
	 * in ksmbd before.
	 */
	sp->max_fragmented_recv_size = (sp->recv_credit_max * sp->max_recv_size) / 2;

	/*
	 * We take the value from the peer, which is checked to be higher than 0,
	 * but we limit it to the max value we support in order to have
	 * the main logic simpler.
	 */
	sc->recv_io.credits.target = credits_requested;
	sc->recv_io.credits.target = min_t(u16, sc->recv_io.credits.target,
					   sp->recv_credit_max);

	/*
	 * Note nreq->max_receive_size was already checked against
	 * SMBDIRECT_MIN_RECEIVE_SIZE above.
	 */
	sp->max_send_size = min_t(u32, sp->max_send_size, max_receive_size);

	/*
	 * Note nreq->max_fragmented_size was already checked against
	 * SMBDIRECT_MIN_FRAGMENTED_SIZE above.
	 */
	sp->max_fragmented_send_size = max_fragmented_size;

	if (sc->accept.listener) {
		struct smbdirect_socket *lsc = sc->accept.listener;
		unsigned long flags;

		spin_lock_irqsave(&lsc->listen.lock, flags);
		list_del(&sc->accept.list);
		list_add_tail(&sc->accept.list, &lsc->listen.ready);
		wake_up(&lsc->listen.wait_queue);
		spin_unlock_irqrestore(&lsc->listen.lock, flags);

		/*
		 * smbdirect_socket_accept() will call
		 * smbdirect_accept_negotiate_finish(nsc, 0);
		 *
		 * So that we don't send the negotiation
		 * response that grants credits to the peer
		 * before the socket is accepted by the
		 * application.
		 */
		return;
	}

	ntstatus = le32_to_cpu(STATUS_SUCCESS);

not_supported:
	smbdirect_accept_negotiate_finish(sc, ntstatus);
}

void smbdirect_accept_negotiate_finish(struct smbdirect_socket *sc, u32 ntstatus)
{
	const struct smbdirect_socket_parameters *sp = &sc->parameters;
	struct smbdirect_recv_io *recv_io;
	struct smbdirect_send_io *send_io;
	struct smbdirect_negotiate_resp *nrep;
	int posted;
	u16 new_credits;
	int ret;

	if (ntstatus)
		goto not_supported;

	/*
	 * Prepare for receiving data_transfer messages
	 */
	sc->recv_io.reassembly.full_packet_received = true;
	sc->recv_io.expected = SMBDIRECT_EXPECT_DATA_TRANSFER;
	list_for_each_entry(recv_io, &sc->recv_io.free.list, list)
		recv_io->cqe.done = smbdirect_connection_recv_io_done;
	recv_io = NULL;

	/*
	 * We should at least post 1 smbdirect_recv_io!
	 */
	posted = smbdirect_connection_recv_io_refill(sc);
	if (posted < 1) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_recv_io_refill() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(posted));
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
		return;
	}

	/*
	 * The response will grant credits for all posted
	 * smbdirect_recv_io messages.
	 */
	new_credits = smbdirect_connection_grant_recv_credits(sc);

not_supported:
	send_io = smbdirect_connection_alloc_send_io(sc);
	if (IS_ERR(send_io)) {
		ret = PTR_ERR(send_io);
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_alloc_send_io() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		smbdirect_socket_schedule_cleanup(sc, ret);
		return;
	}
	send_io->cqe.done = smbdirect_accept_negotiate_send_done;

	nrep = (struct smbdirect_negotiate_resp *)send_io->packet;
	nrep->min_version = cpu_to_le16(SMBDIRECT_V1);
	nrep->max_version = cpu_to_le16(SMBDIRECT_V1);
	if (ntstatus == 0) {
		nrep->negotiated_version = cpu_to_le16(SMBDIRECT_V1);
		nrep->reserved = 0;
		nrep->credits_requested = cpu_to_le16(sp->send_credit_target);
		nrep->credits_granted = cpu_to_le16(new_credits);
		nrep->status = cpu_to_le32(ntstatus);
		nrep->max_readwrite_size = cpu_to_le32(sp->max_read_write_size);
		nrep->preferred_send_size = cpu_to_le32(sp->max_send_size);
		nrep->max_receive_size = cpu_to_le32(sp->max_recv_size);
		nrep->max_fragmented_size = cpu_to_le32(sp->max_fragmented_recv_size);
	} else {
		nrep->negotiated_version = 0;
		nrep->reserved = 0;
		nrep->credits_requested = 0;
		nrep->credits_granted = 0;
		nrep->status = cpu_to_le32(ntstatus);
		nrep->max_readwrite_size = 0;
		nrep->preferred_send_size = 0;
		nrep->max_receive_size = 0;
		nrep->max_fragmented_size = 0;
	}

	smbdirect_log_negotiate(sc, SMBDIRECT_LOG_INFO,
		"RepOut: %s%x, %s%x, %s%x, %s%u, %s%u, %s%x, %s%u, %s%u, %s%u, %s%u\n",
		"MinVersion=0x",
		le16_to_cpu(nrep->min_version),
		"MaxVersion=0x",
		le16_to_cpu(nrep->max_version),
		"NegotiatedVersion=0x",
		le16_to_cpu(nrep->negotiated_version),
		"CreditsRequested=",
		le16_to_cpu(nrep->credits_requested),
		"CreditsGranted=",
		le16_to_cpu(nrep->credits_granted),
		"Status=0x",
		le32_to_cpu(nrep->status),
		"MaxReadWriteSize=",
		le32_to_cpu(nrep->max_readwrite_size),
		"PreferredSendSize=",
		le32_to_cpu(nrep->preferred_send_size),
		"MaxRecvSize=",
		le32_to_cpu(nrep->max_receive_size),
		"MaxFragmentedSize=",
		le32_to_cpu(nrep->max_fragmented_size));

	send_io->sge[0].addr = ib_dma_map_single(sc->ib.dev,
						 nrep,
						 sizeof(*nrep),
						 DMA_TO_DEVICE);
	ret = ib_dma_mapping_error(sc->ib.dev, send_io->sge[0].addr);
	if (ret) {
		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"ib_dma_mapping_error() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		smbdirect_connection_free_send_io(send_io);
		smbdirect_socket_schedule_cleanup(sc, ret);
		return;
	}

	send_io->sge[0].length = sizeof(*nrep);
	send_io->sge[0].lkey = sc->ib.pd->local_dma_lkey;
	send_io->num_sge = 1;

	ib_dma_sync_single_for_device(sc->ib.dev,
				      send_io->sge[0].addr,
				      send_io->sge[0].length,
				      DMA_TO_DEVICE);

	send_io->wr.next = NULL;
	send_io->wr.wr_cqe = &send_io->cqe;
	send_io->wr.sg_list = send_io->sge;
	send_io->wr.num_sge = send_io->num_sge;
	send_io->wr.opcode = IB_WR_SEND;
	send_io->wr.send_flags = IB_SEND_SIGNALED;

	ret = smbdirect_connection_post_send_wr(sc, &send_io->wr);
	if (ret) {
		/* if we reach here, post send failed */
		smbdirect_log_rdma_send(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_post_send_wr() failed %1pe\n",
			SMBDIRECT_DEBUG_ERR_PTR(ret));
		/*
		 * Note smbdirect_connection_free_send_io()
		 * does ib_dma_unmap_page()
		 */
		smbdirect_connection_free_send_io(send_io);
		smbdirect_socket_schedule_cleanup(sc, ret);
		return;
	}

	/*
	 * smbdirect_accept_negotiate_send_done
	 * will do all remaining work...
	 */
}

static void smbdirect_accept_negotiate_send_done(struct ib_cq *cq, struct ib_wc *wc)
{
	struct smbdirect_send_io *send_io =
		container_of(wc->wr_cqe, struct smbdirect_send_io, cqe);
	struct smbdirect_socket *sc = send_io->socket;
	struct smbdirect_negotiate_resp *nrep;
	u32 ntstatus;

	smbdirect_log_rdma_send(sc, SMBDIRECT_LOG_INFO,
		"smbdirect_send_io completed. status='%s (%d)', opcode=%d\n",
		ib_wc_status_msg(wc->status), wc->status, wc->opcode);

	nrep = (struct smbdirect_negotiate_resp *)send_io->packet;
	ntstatus = le32_to_cpu(nrep->status);

	/* Note this frees wc->wr_cqe, but not wc */
	smbdirect_connection_free_send_io(send_io);
	atomic_dec(&sc->send_io.pending.count);

	if (unlikely(wc->status != IB_WC_SUCCESS || WARN_ON_ONCE(wc->opcode != IB_WC_SEND))) {
		if (wc->status != IB_WC_WR_FLUSH_ERR)
			smbdirect_log_rdma_send(sc, SMBDIRECT_LOG_ERR,
				"wc->status=%s (%d) wc->opcode=%d\n",
				ib_wc_status_msg(wc->status), wc->status, wc->opcode);
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
		return;
	}

	/*
	 * If we send a smbdirect_negotiate_resp without NT_STATUS_OK (0)
	 * we need to disconnect now.
	 *
	 * Otherwise smbdirect_connection_negotiation_done()
	 * will setup all required things and wake up
	 * the waiter.
	 */
	if (ntstatus)
		smbdirect_socket_schedule_cleanup(sc, -EOPNOTSUPP);
	else
		smbdirect_connection_negotiation_done(sc);
}

static int smbdirect_accept_rdma_event_handler(struct rdma_cm_id *id,
					       struct rdma_cm_event *event)
{
	struct smbdirect_socket *sc = id->context;
	unsigned long flags;

	/*
	 * cma_cm_event_handler() has
	 * lockdep_assert_held(&id_priv->handler_mutex);
	 *
	 * Mutexes are not allowed in interrupts,
	 * and we rely on not being in an interrupt here,
	 * as we might sleep.
	 *
	 * We didn't timeout so we cancel our idle timer,
	 * it will be scheduled again if needed.
	 */
	WARN_ON_ONCE(in_interrupt());

	if (event->status || event->event != sc->rdma.expected_event) {
		int ret = -ECONNABORTED;

		if (event->event == RDMA_CM_EVENT_REJECTED)
			ret = -ECONNREFUSED;
		if (event->event == RDMA_CM_EVENT_DEVICE_REMOVAL)
			ret = -ENETDOWN;
		if (IS_ERR(SMBDIRECT_DEBUG_ERR_PTR(event->status)))
			ret = event->status;

		smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_ERR,
			"%s (first_error=%1pe, expected=%s) => event=%s status=%d => ret=%1pe\n",
			smbdirect_socket_status_string(sc->status),
			SMBDIRECT_DEBUG_ERR_PTR(sc->first_error),
			rdma_event_msg(sc->rdma.expected_event),
			rdma_event_msg(event->event),
			event->status,
			SMBDIRECT_DEBUG_ERR_PTR(ret));

		smbdirect_socket_schedule_cleanup(sc, ret);
		return 0;
	}

	smbdirect_log_rdma_event(sc, SMBDIRECT_LOG_INFO,
		"%s (first_error=%1pe) event=%s\n",
		smbdirect_socket_status_string(sc->status),
		SMBDIRECT_DEBUG_ERR_PTR(sc->first_error),
		rdma_event_msg(event->event));

	if (sc->first_error)
		return 0;

	switch (event->event) {
	case RDMA_CM_EVENT_ESTABLISHED:
		smbdirect_connection_rdma_established(sc);

		/*
		 * Some drivers (at least mlx5_ib and irdma) might post a
		 * recv completion before RDMA_CM_EVENT_ESTABLISHED,
		 * we need to adjust our expectation in that case.
		 *
		 * If smbdirect_accept_negotiate_recv_done was called first
		 * it initialized sc->connect.work only for us to
		 * start, so that we turned into
		 * SMBDIRECT_SOCKET_NEGOTIATE_NEEDED, before
		 * smbdirect_accept_negotiate_recv_work() runs.
		 *
		 * If smbdirect_accept_negotiate_recv_done didn't happen
		 * yet. sc->connect.work is still be disabled and
		 * queue_work() is a no-op.
		 */
		if (SMBDIRECT_CHECK_STATUS_DISCONNECT(sc, SMBDIRECT_SOCKET_RDMA_CONNECT_RUNNING))
			return 0;
		sc->status = SMBDIRECT_SOCKET_NEGOTIATE_NEEDED;
		spin_lock_irqsave(&sc->connect.lock, flags);
		if (!sc->first_error)
			queue_work(sc->workqueues.accept, &sc->connect.work);
		spin_unlock_irqrestore(&sc->connect.lock, flags);

		/*
		 * wait for smbdirect_accept_negotiate_recv_done()
		 * to get the negotiate request.
		 */
		return 0;

	default:
		break;
	}

	/*
	 * This is an internal error
	 */
	WARN_ON_ONCE(sc->rdma.expected_event != RDMA_CM_EVENT_ESTABLISHED);
	smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
	return 0;
}

static long smbdirect_socket_wait_for_accept(struct smbdirect_socket *lsc, long timeo)
{
	long ret;

	ret = wait_event_interruptible_timeout(lsc->listen.wait_queue,
					       !list_empty_careful(&lsc->listen.ready) ||
					       lsc->status != SMBDIRECT_SOCKET_LISTENING ||
					       lsc->first_error,
					       timeo);
	if (lsc->status != SMBDIRECT_SOCKET_LISTENING)
		return -EINVAL;
	if (lsc->first_error)
		return lsc->first_error;
	if (!ret)
		ret = -ETIMEDOUT;
	if (ret < 0)
		return ret;

	return 0;
}

struct smbdirect_socket *smbdirect_socket_accept(struct smbdirect_socket *lsc,
						 long timeo,
						 struct proto_accept_arg *arg)
{
	struct smbdirect_socket *nsc;
	unsigned long flags;

	if (lsc->status != SMBDIRECT_SOCKET_LISTENING) {
		arg->err = -EINVAL;
		return NULL;
	}

	if (lsc->first_error) {
		arg->err = lsc->first_error;
		return NULL;
	}

	if (list_empty_careful(&lsc->listen.ready)) {
		int ret;

		if (timeo == 0) {
			arg->err = -EAGAIN;
			return NULL;
		}

		ret = smbdirect_socket_wait_for_accept(lsc, timeo);
		if (ret) {
			arg->err = ret;
			return NULL;
		}
	}

	spin_lock_irqsave(&lsc->listen.lock, flags);
	nsc = list_first_entry_or_null(&lsc->listen.ready,
				       struct smbdirect_socket,
				       accept.list);
	if (nsc) {
		nsc->accept.listener = NULL;
		list_del_init_careful(&nsc->accept.list);
		arg->is_empty = list_empty_careful(&lsc->listen.ready);
	}
	spin_unlock_irqrestore(&lsc->listen.lock, flags);
	if (!nsc) {
		arg->err = -EAGAIN;
		return NULL;
	}

	/*
	 * We did not send the negotiation response
	 * yet, so we did not grant any credits to the client,
	 * so it didn't grant any credits to us.
	 *
	 * The caller expects a connected socket
	 * now as there are no credits anyway.
	 *
	 * Then we send the negotiation response in
	 * order to grant credits to the peer.
	 */
	nsc->status = SMBDIRECT_SOCKET_CONNECTED;
	smbdirect_accept_negotiate_finish(nsc, 0);

	return nsc;
}
__SMBDIRECT_EXPORT_SYMBOL__(smbdirect_socket_accept);