*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  *   the GNU General Public License for more details.
  */
+#include <linux/module.h>
 #include "smbdirect.h"
+#include "cifs_debug.h"
+
+static struct smbd_response *get_empty_queue_buffer(
+               struct smbd_connection *info);
+static struct smbd_response *get_receive_buffer(
+               struct smbd_connection *info);
+static void put_receive_buffer(
+               struct smbd_connection *info,
+               struct smbd_response *response);
+static int allocate_receive_buffers(struct smbd_connection *info, int num_buf);
+static void destroy_receive_buffers(struct smbd_connection *info);
+
+static void put_empty_packet(
+               struct smbd_connection *info, struct smbd_response *response);
+static void enqueue_reassembly(
+               struct smbd_connection *info,
+               struct smbd_response *response, int data_length);
+static struct smbd_response *_get_first_reassembly(
+               struct smbd_connection *info);
+
+static int smbd_post_recv(
+               struct smbd_connection *info,
+               struct smbd_response *response);
+
+static int smbd_post_send_empty(struct smbd_connection *info);
 
 /* SMBD version number */
 #define SMBD_V1        0x0100
 
 /* If payload is less than this byte, use RDMA send/recv not read/write */
 int rdma_readwrite_threshold = 4096;
+
+/* Transport logging functions
+ * Logging are defined as classes. They can be OR'ed to define the actual
+ * logging level via module parameter smbd_logging_class
+ * e.g. cifs.smbd_logging_class=0xa0 will log all log_rdma_recv() and
+ * log_rdma_event()
+ */
+#define LOG_OUTGOING                   0x1
+#define LOG_INCOMING                   0x2
+#define LOG_READ                       0x4
+#define LOG_WRITE                      0x8
+#define LOG_RDMA_SEND                  0x10
+#define LOG_RDMA_RECV                  0x20
+#define LOG_KEEP_ALIVE                 0x40
+#define LOG_RDMA_EVENT                 0x80
+#define LOG_RDMA_MR                    0x100
+static unsigned int smbd_logging_class;
+module_param(smbd_logging_class, uint, 0644);
+MODULE_PARM_DESC(smbd_logging_class,
+       "Logging class for SMBD transport 0x0 to 0x100");
+
+#define ERR            0x0
+#define INFO           0x1
+static unsigned int smbd_logging_level = ERR;
+module_param(smbd_logging_level, uint, 0644);
+MODULE_PARM_DESC(smbd_logging_level,
+       "Logging level for SMBD transport, 0 (default): error, 1: info");
+
+#define log_rdma(level, class, fmt, args...)                           \
+do {                                                                   \
+       if (level <= smbd_logging_level || class & smbd_logging_class)  \
+               cifs_dbg(VFS, "%s:%d " fmt, __func__, __LINE__, ##args);\
+} while (0)
+
+#define log_outgoing(level, fmt, args...) \
+               log_rdma(level, LOG_OUTGOING, fmt, ##args)
+#define log_incoming(level, fmt, args...) \
+               log_rdma(level, LOG_INCOMING, fmt, ##args)
+#define log_read(level, fmt, args...)  log_rdma(level, LOG_READ, fmt, ##args)
+#define log_write(level, fmt, args...) log_rdma(level, LOG_WRITE, fmt, ##args)
+#define log_rdma_send(level, fmt, args...) \
+               log_rdma(level, LOG_RDMA_SEND, fmt, ##args)
+#define log_rdma_recv(level, fmt, args...) \
+               log_rdma(level, LOG_RDMA_RECV, fmt, ##args)
+#define log_keep_alive(level, fmt, args...) \
+               log_rdma(level, LOG_KEEP_ALIVE, fmt, ##args)
+#define log_rdma_event(level, fmt, args...) \
+               log_rdma(level, LOG_RDMA_EVENT, fmt, ##args)
+#define log_rdma_mr(level, fmt, args...) \
+               log_rdma(level, LOG_RDMA_MR, fmt, ##args)
+
+/*
+ * Destroy the transport and related RDMA and memory resources
+ * Need to go through all the pending counters and make sure on one is using
+ * the transport while it is destroyed
+ */
+static void smbd_destroy_rdma_work(struct work_struct *work)
+{
+       struct smbd_response *response;
+       struct smbd_connection *info =
+               container_of(work, struct smbd_connection, destroy_work);
+       unsigned long flags;
+
+       log_rdma_event(INFO, "destroying qp\n");
+       ib_drain_qp(info->id->qp);
+       rdma_destroy_qp(info->id);
+
+       /* Unblock all I/O waiting on the send queue */
+       wake_up_interruptible_all(&info->wait_send_queue);
+
+       log_rdma_event(INFO, "cancelling idle timer\n");
+       cancel_delayed_work_sync(&info->idle_timer_work);
+       log_rdma_event(INFO, "cancelling send immediate work\n");
+       cancel_delayed_work_sync(&info->send_immediate_work);
+
+       log_rdma_event(INFO, "wait for all recv to finish\n");
+       wake_up_interruptible(&info->wait_reassembly_queue);
+
+       log_rdma_event(INFO, "wait for all send posted to IB to finish\n");
+       wait_event(info->wait_send_pending,
+               atomic_read(&info->send_pending) == 0);
+       wait_event(info->wait_send_payload_pending,
+               atomic_read(&info->send_payload_pending) == 0);
+
+       /* It's not posssible for upper layer to get to reassembly */
+       log_rdma_event(INFO, "drain the reassembly queue\n");
+       do {
+               spin_lock_irqsave(&info->reassembly_queue_lock, flags);
+               response = _get_first_reassembly(info);
+               if (response) {
+                       list_del(&response->list);
+                       spin_unlock_irqrestore(
+                               &info->reassembly_queue_lock, flags);
+                       put_receive_buffer(info, response);
+               }
+       } while (response);
+       spin_unlock_irqrestore(&info->reassembly_queue_lock, flags);
+       info->reassembly_data_length = 0;
+
+       log_rdma_event(INFO, "free receive buffers\n");
+       wait_event(info->wait_receive_queues,
+               info->count_receive_queue + info->count_empty_packet_queue
+                       == info->receive_credit_max);
+       destroy_receive_buffers(info);
+
+       ib_free_cq(info->send_cq);
+       ib_free_cq(info->recv_cq);
+       ib_dealloc_pd(info->pd);
+       rdma_destroy_id(info->id);
+
+       /* free mempools */
+       mempool_destroy(info->request_mempool);
+       kmem_cache_destroy(info->request_cache);
+
+       mempool_destroy(info->response_mempool);
+       kmem_cache_destroy(info->response_cache);
+
+       info->transport_status = SMBD_DESTROYED;
+       wake_up_all(&info->wait_destroy);
+}
+
+static int smbd_process_disconnected(struct smbd_connection *info)
+{
+       schedule_work(&info->destroy_work);
+       return 0;
+}
+
+static void smbd_disconnect_rdma_work(struct work_struct *work)
+{
+       struct smbd_connection *info =
+               container_of(work, struct smbd_connection, disconnect_work);
+
+       if (info->transport_status == SMBD_CONNECTED) {
+               info->transport_status = SMBD_DISCONNECTING;
+               rdma_disconnect(info->id);
+       }
+}
+
+static void smbd_disconnect_rdma_connection(struct smbd_connection *info)
+{
+       queue_work(info->workqueue, &info->disconnect_work);
+}
+
+/* Upcall from RDMA CM */
+static int smbd_conn_upcall(
+               struct rdma_cm_id *id, struct rdma_cm_event *event)
+{
+       struct smbd_connection *info = id->context;
+
+       log_rdma_event(INFO, "event=%d status=%d\n",
+               event->event, event->status);
+
+       switch (event->event) {
+       case RDMA_CM_EVENT_ADDR_RESOLVED:
+       case RDMA_CM_EVENT_ROUTE_RESOLVED:
+               info->ri_rc = 0;
+               complete(&info->ri_done);
+               break;
+
+       case RDMA_CM_EVENT_ADDR_ERROR:
+               info->ri_rc = -EHOSTUNREACH;
+               complete(&info->ri_done);
+               break;
+
+       case RDMA_CM_EVENT_ROUTE_ERROR:
+               info->ri_rc = -ENETUNREACH;
+               complete(&info->ri_done);
+               break;
+
+       case RDMA_CM_EVENT_ESTABLISHED:
+               log_rdma_event(INFO, "connected event=%d\n", event->event);
+               info->transport_status = SMBD_CONNECTED;
+               wake_up_interruptible(&info->conn_wait);
+               break;
+
+       case RDMA_CM_EVENT_CONNECT_ERROR:
+       case RDMA_CM_EVENT_UNREACHABLE:
+       case RDMA_CM_EVENT_REJECTED:
+               log_rdma_event(INFO, "connecting failed event=%d\n", event->event);
+               info->transport_status = SMBD_DISCONNECTED;
+               wake_up_interruptible(&info->conn_wait);
+               break;
+
+       case RDMA_CM_EVENT_DEVICE_REMOVAL:
+       case RDMA_CM_EVENT_DISCONNECTED:
+               /* This happenes when we fail the negotiation */
+               if (info->transport_status == SMBD_NEGOTIATE_FAILED) {
+                       info->transport_status = SMBD_DISCONNECTED;
+                       wake_up(&info->conn_wait);
+                       break;
+               }
+
+               info->transport_status = SMBD_DISCONNECTED;
+               smbd_process_disconnected(info);
+               break;
+
+       default:
+               break;
+       }
+
+       return 0;
+}
+
+/* Upcall from RDMA QP */
+static void
+smbd_qp_async_error_upcall(struct ib_event *event, void *context)
+{
+       struct smbd_connection *info = context;
+
+       log_rdma_event(ERR, "%s on device %s info %p\n",
+               ib_event_msg(event->event), event->device->name, info);
+
+       switch (event->event) {
+       case IB_EVENT_CQ_ERR:
+       case IB_EVENT_QP_FATAL:
+               smbd_disconnect_rdma_connection(info);
+
+       default:
+               break;
+       }
+}
+
+static inline void *smbd_request_payload(struct smbd_request *request)
+{
+       return (void *)request->packet;
+}
+
+static inline void *smbd_response_payload(struct smbd_response *response)
+{
+       return (void *)response->packet;
+}
+
+/* Called when a RDMA send is done */
+static void send_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       int i;
+       struct smbd_request *request =
+               container_of(wc->wr_cqe, struct smbd_request, cqe);
+
+       log_rdma_send(INFO, "smbd_request %p completed wc->status=%d\n",
+               request, wc->status);
+
+       if (wc->status != IB_WC_SUCCESS || wc->opcode != IB_WC_SEND) {
+               log_rdma_send(ERR, "wc->status=%d wc->opcode=%d\n",
+                       wc->status, wc->opcode);
+               smbd_disconnect_rdma_connection(request->info);
+       }
+
+       for (i = 0; i < request->num_sge; i++)
+               ib_dma_unmap_single(request->info->id->device,
+                       request->sge[i].addr,
+                       request->sge[i].length,
+                       DMA_TO_DEVICE);
+
+       if (request->has_payload) {
+               if (atomic_dec_and_test(&request->info->send_payload_pending))
+                       wake_up(&request->info->wait_send_payload_pending);
+       } else {
+               if (atomic_dec_and_test(&request->info->send_pending))
+                       wake_up(&request->info->wait_send_pending);
+       }
+
+       mempool_free(request, request->info->request_mempool);
+}
+
+static void dump_smbd_negotiate_resp(struct smbd_negotiate_resp *resp)
+{
+       log_rdma_event(INFO, "resp message min_version %u max_version %u "
+               "negotiated_version %u credits_requested %u "
+               "credits_granted %u status %u max_readwrite_size %u "
+               "preferred_send_size %u max_receive_size %u "
+               "max_fragmented_size %u\n",
+               resp->min_version, resp->max_version, resp->negotiated_version,
+               resp->credits_requested, resp->credits_granted, resp->status,
+               resp->max_readwrite_size, resp->preferred_send_size,
+               resp->max_receive_size, resp->max_fragmented_size);
+}
+
+/*
+ * Process a negotiation response message, according to [MS-SMBD]3.1.5.7
+ * response, packet_length: the negotiation response message
+ * return value: true if negotiation is a success, false if failed
+ */
+static bool process_negotiation_response(
+               struct smbd_response *response, int packet_length)
+{
+       struct smbd_connection *info = response->info;
+       struct smbd_negotiate_resp *packet = smbd_response_payload(response);
+
+       if (packet_length < sizeof(struct smbd_negotiate_resp)) {
+               log_rdma_event(ERR,
+                       "error: packet_length=%d\n", packet_length);
+               return false;
+       }
+
+       if (le16_to_cpu(packet->negotiated_version) != SMBD_V1) {
+               log_rdma_event(ERR, "error: negotiated_version=%x\n",
+                       le16_to_cpu(packet->negotiated_version));
+               return false;
+       }
+       info->protocol = le16_to_cpu(packet->negotiated_version);
+
+       if (packet->credits_requested == 0) {
+               log_rdma_event(ERR, "error: credits_requested==0\n");
+               return false;
+       }
+       info->receive_credit_target = le16_to_cpu(packet->credits_requested);
+
+       if (packet->credits_granted == 0) {
+               log_rdma_event(ERR, "error: credits_granted==0\n");
+               return false;
+       }
+       atomic_set(&info->send_credits, le16_to_cpu(packet->credits_granted));
+
+       atomic_set(&info->receive_credits, 0);
+
+       if (le32_to_cpu(packet->preferred_send_size) > info->max_receive_size) {
+               log_rdma_event(ERR, "error: preferred_send_size=%d\n",
+                       le32_to_cpu(packet->preferred_send_size));
+               return false;
+       }
+       info->max_receive_size = le32_to_cpu(packet->preferred_send_size);
+
+       if (le32_to_cpu(packet->max_receive_size) < SMBD_MIN_RECEIVE_SIZE) {
+               log_rdma_event(ERR, "error: max_receive_size=%d\n",
+                       le32_to_cpu(packet->max_receive_size));
+               return false;
+       }
+       info->max_send_size = min_t(int, info->max_send_size,
+                                       le32_to_cpu(packet->max_receive_size));
+
+       if (le32_to_cpu(packet->max_fragmented_size) <
+                       SMBD_MIN_FRAGMENTED_SIZE) {
+               log_rdma_event(ERR, "error: max_fragmented_size=%d\n",
+                       le32_to_cpu(packet->max_fragmented_size));
+               return false;
+       }
+       info->max_fragmented_send_size =
+               le32_to_cpu(packet->max_fragmented_size);
+
+       return true;
+}
+
+/*
+ * Check and schedule to send an immediate packet
+ * This is used to extend credtis to remote peer to keep the transport busy
+ */
+static void check_and_send_immediate(struct smbd_connection *info)
+{
+       if (info->transport_status != SMBD_CONNECTED)
+               return;
+
+       info->send_immediate = true;
+
+       /*
+        * Promptly send a packet if our peer is running low on receive
+        * credits
+        */
+       if (atomic_read(&info->receive_credits) <
+               info->receive_credit_target - 1)
+               queue_delayed_work(
+                       info->workqueue, &info->send_immediate_work, 0);
+}
+
+static void smbd_post_send_credits(struct work_struct *work)
+{
+       int ret = 0;
+       int use_receive_queue = 1;
+       int rc;
+       struct smbd_response *response;
+       struct smbd_connection *info =
+               container_of(work, struct smbd_connection,
+                       post_send_credits_work);
+
+       if (info->transport_status != SMBD_CONNECTED) {
+               wake_up(&info->wait_receive_queues);
+               return;
+       }
+
+       if (info->receive_credit_target >
+               atomic_read(&info->receive_credits)) {
+               while (true) {
+                       if (use_receive_queue)
+                               response = get_receive_buffer(info);
+                       else
+                               response = get_empty_queue_buffer(info);
+                       if (!response) {
+                               /* now switch to emtpy packet queue */
+                               if (use_receive_queue) {
+                                       use_receive_queue = 0;
+                                       continue;
+                               } else
+                                       break;
+                       }
+
+                       response->type = SMBD_TRANSFER_DATA;
+                       response->first_segment = false;
+                       rc = smbd_post_recv(info, response);
+                       if (rc) {
+                               log_rdma_recv(ERR,
+                                       "post_recv failed rc=%d\n", rc);
+                               put_receive_buffer(info, response);
+                               break;
+                       }
+
+                       ret++;
+               }
+       }
+
+       spin_lock(&info->lock_new_credits_offered);
+       info->new_credits_offered += ret;
+       spin_unlock(&info->lock_new_credits_offered);
+
+       atomic_add(ret, &info->receive_credits);
+
+       /* Check if we can post new receive and grant credits to peer */
+       check_and_send_immediate(info);
+}
+
+static void smbd_recv_done_work(struct work_struct *work)
+{
+       struct smbd_connection *info =
+               container_of(work, struct smbd_connection, recv_done_work);
+
+       /*
+        * We may have new send credits granted from remote peer
+        * If any sender is blcoked on lack of credets, unblock it
+        */
+       if (atomic_read(&info->send_credits))
+               wake_up_interruptible(&info->wait_send_queue);
+
+       /*
+        * Check if we need to send something to remote peer to
+        * grant more credits or respond to KEEP_ALIVE packet
+        */
+       check_and_send_immediate(info);
+}
+
+/* Called from softirq, when recv is done */
+static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       struct smbd_data_transfer *data_transfer;
+       struct smbd_response *response =
+               container_of(wc->wr_cqe, struct smbd_response, cqe);
+       struct smbd_connection *info = response->info;
+       int data_length = 0;
+
+       log_rdma_recv(INFO, "response=%p type=%d wc status=%d wc opcode %d "
+                     "byte_len=%d pkey_index=%x\n",
+               response, response->type, wc->status, wc->opcode,
+               wc->byte_len, wc->pkey_index);
+
+       if (wc->status != IB_WC_SUCCESS || wc->opcode != IB_WC_RECV) {
+               log_rdma_recv(INFO, "wc->status=%d opcode=%d\n",
+                       wc->status, wc->opcode);
+               smbd_disconnect_rdma_connection(info);
+               goto error;
+       }
+
+       ib_dma_sync_single_for_cpu(
+               wc->qp->device,
+               response->sge.addr,
+               response->sge.length,
+               DMA_FROM_DEVICE);
+
+       switch (response->type) {
+       /* SMBD negotiation response */
+       case SMBD_NEGOTIATE_RESP:
+               dump_smbd_negotiate_resp(smbd_response_payload(response));
+               info->full_packet_received = true;
+               info->negotiate_done =
+                       process_negotiation_response(response, wc->byte_len);
+               complete(&info->negotiate_completion);
+               break;
+
+       /* SMBD data transfer packet */
+       case SMBD_TRANSFER_DATA:
+               data_transfer = smbd_response_payload(response);
+               data_length = le32_to_cpu(data_transfer->data_length);
+
+               /*
+                * If this is a packet with data playload place the data in
+                * reassembly queue and wake up the reading thread
+                */
+               if (data_length) {
+                       if (info->full_packet_received)
+                               response->first_segment = true;
+
+                       if (le32_to_cpu(data_transfer->remaining_data_length))
+                               info->full_packet_received = false;
+                       else
+                               info->full_packet_received = true;
+
+                       enqueue_reassembly(
+                               info,
+                               response,
+                               data_length);
+               } else
+                       put_empty_packet(info, response);
+
+               if (data_length)
+                       wake_up_interruptible(&info->wait_reassembly_queue);
+
+               atomic_dec(&info->receive_credits);
+               info->receive_credit_target =
+                       le16_to_cpu(data_transfer->credits_requested);
+               atomic_add(le16_to_cpu(data_transfer->credits_granted),
+                       &info->send_credits);
+
+               log_incoming(INFO, "data flags %d data_offset %d "
+                       "data_length %d remaining_data_length %d\n",
+                       le16_to_cpu(data_transfer->flags),
+                       le32_to_cpu(data_transfer->data_offset),
+                       le32_to_cpu(data_transfer->data_length),
+                       le32_to_cpu(data_transfer->remaining_data_length));
+
+               /* Send a KEEP_ALIVE response right away if requested */
+               info->keep_alive_requested = KEEP_ALIVE_NONE;
+               if (le16_to_cpu(data_transfer->flags) &
+                               SMB_DIRECT_RESPONSE_REQUESTED) {
+                       info->keep_alive_requested = KEEP_ALIVE_PENDING;
+               }
+
+               queue_work(info->workqueue, &info->recv_done_work);
+               return;
+
+       default:
+               log_rdma_recv(ERR,
+                       "unexpected response type=%d\n", response->type);
+       }
+
+error:
+       put_receive_buffer(info, response);
+}
+
+static struct rdma_cm_id *smbd_create_id(
+               struct smbd_connection *info,
+               struct sockaddr *dstaddr, int port)
+{
+       struct rdma_cm_id *id;
+       int rc;
+       __be16 *sport;
+
+       id = rdma_create_id(&init_net, smbd_conn_upcall, info,
+               RDMA_PS_TCP, IB_QPT_RC);
+       if (IS_ERR(id)) {
+               rc = PTR_ERR(id);
+               log_rdma_event(ERR, "rdma_create_id() failed %i\n", rc);
+               return id;
+       }
+
+       if (dstaddr->sa_family == AF_INET6)
+               sport = &((struct sockaddr_in6 *)dstaddr)->sin6_port;
+       else
+               sport = &((struct sockaddr_in *)dstaddr)->sin_port;
+
+       *sport = htons(port);
+
+       init_completion(&info->ri_done);
+       info->ri_rc = -ETIMEDOUT;
+
+       rc = rdma_resolve_addr(id, NULL, (struct sockaddr *)dstaddr,
+               RDMA_RESOLVE_TIMEOUT);
+       if (rc) {
+               log_rdma_event(ERR, "rdma_resolve_addr() failed %i\n", rc);
+               goto out;
+       }
+       wait_for_completion_interruptible_timeout(
+               &info->ri_done, msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT));
+       rc = info->ri_rc;
+       if (rc) {
+               log_rdma_event(ERR, "rdma_resolve_addr() completed %i\n", rc);
+               goto out;
+       }
+
+       info->ri_rc = -ETIMEDOUT;
+       rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
+       if (rc) {
+               log_rdma_event(ERR, "rdma_resolve_route() failed %i\n", rc);
+               goto out;
+       }
+       wait_for_completion_interruptible_timeout(
+               &info->ri_done, msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT));
+       rc = info->ri_rc;
+       if (rc) {
+               log_rdma_event(ERR, "rdma_resolve_route() completed %i\n", rc);
+               goto out;
+       }
+
+       return id;
+
+out:
+       rdma_destroy_id(id);
+       return ERR_PTR(rc);
+}
+
+/*
+ * Test if FRWR (Fast Registration Work Requests) is supported on the device
+ * This implementation requries FRWR on RDMA read/write
+ * return value: true if it is supported
+ */
+static bool frwr_is_supported(struct ib_device_attr *attrs)
+{
+       if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS))
+               return false;
+       if (attrs->max_fast_reg_page_list_len == 0)
+               return false;
+       return true;
+}
+
+static int smbd_ia_open(
+               struct smbd_connection *info,
+               struct sockaddr *dstaddr, int port)
+{
+       int rc;
+
+       info->id = smbd_create_id(info, dstaddr, port);
+       if (IS_ERR(info->id)) {
+               rc = PTR_ERR(info->id);
+               goto out1;
+       }
+
+       if (!frwr_is_supported(&info->id->device->attrs)) {
+               log_rdma_event(ERR,
+                       "Fast Registration Work Requests "
+                       "(FRWR) is not supported\n");
+               log_rdma_event(ERR,
+                       "Device capability flags = %llx "
+                       "max_fast_reg_page_list_len = %u\n",
+                       info->id->device->attrs.device_cap_flags,
+                       info->id->device->attrs.max_fast_reg_page_list_len);
+               rc = -EPROTONOSUPPORT;
+               goto out2;
+       }
+
+       info->pd = ib_alloc_pd(info->id->device, 0);
+       if (IS_ERR(info->pd)) {
+               rc = PTR_ERR(info->pd);
+               log_rdma_event(ERR, "ib_alloc_pd() returned %d\n", rc);
+               goto out2;
+       }
+
+       return 0;
+
+out2:
+       rdma_destroy_id(info->id);
+       info->id = NULL;
+
+out1:
+       return rc;
+}
+
+/*
+ * Send a negotiation request message to the peer
+ * The negotiation procedure is in [MS-SMBD] 3.1.5.2 and 3.1.5.3
+ * After negotiation, the transport is connected and ready for
+ * carrying upper layer SMB payload
+ */
+static int smbd_post_send_negotiate_req(struct smbd_connection *info)
+{
+       struct ib_send_wr send_wr, *send_wr_fail;
+       int rc = -ENOMEM;
+       struct smbd_request *request;
+       struct smbd_negotiate_req *packet;
+
+       request = mempool_alloc(info->request_mempool, GFP_KERNEL);
+       if (!request)
+               return rc;
+
+       request->info = info;
+
+       packet = smbd_request_payload(request);
+       packet->min_version = cpu_to_le16(SMBD_V1);
+       packet->max_version = cpu_to_le16(SMBD_V1);
+       packet->reserved = 0;
+       packet->credits_requested = cpu_to_le16(info->send_credit_target);
+       packet->preferred_send_size = cpu_to_le32(info->max_send_size);
+       packet->max_receive_size = cpu_to_le32(info->max_receive_size);
+       packet->max_fragmented_size =
+               cpu_to_le32(info->max_fragmented_recv_size);
+
+       request->num_sge = 1;
+       request->sge[0].addr = ib_dma_map_single(
+                               info->id->device, (void *)packet,
+                               sizeof(*packet), DMA_TO_DEVICE);
+       if (ib_dma_mapping_error(info->id->device, request->sge[0].addr)) {
+               rc = -EIO;
+               goto dma_mapping_failed;
+       }
+
+       request->sge[0].length = sizeof(*packet);
+       request->sge[0].lkey = info->pd->local_dma_lkey;
+
+       ib_dma_sync_single_for_device(
+               info->id->device, request->sge[0].addr,
+               request->sge[0].length, DMA_TO_DEVICE);
+
+       request->cqe.done = send_done;
+
+       send_wr.next = NULL;
+       send_wr.wr_cqe = &request->cqe;
+       send_wr.sg_list = request->sge;
+       send_wr.num_sge = request->num_sge;
+       send_wr.opcode = IB_WR_SEND;
+       send_wr.send_flags = IB_SEND_SIGNALED;
+
+       log_rdma_send(INFO, "sge addr=%llx length=%x lkey=%x\n",
+               request->sge[0].addr,
+               request->sge[0].length, request->sge[0].lkey);
+
+       request->has_payload = false;
+       atomic_inc(&info->send_pending);
+       rc = ib_post_send(info->id->qp, &send_wr, &send_wr_fail);
+       if (!rc)
+               return 0;
+
+       /* if we reach here, post send failed */
+       log_rdma_send(ERR, "ib_post_send failed rc=%d\n", rc);
+       atomic_dec(&info->send_pending);
+       ib_dma_unmap_single(info->id->device, request->sge[0].addr,
+               request->sge[0].length, DMA_TO_DEVICE);
+
+dma_mapping_failed:
+       mempool_free(request, info->request_mempool);
+       return rc;
+}
+
+/*
+ * Extend the credits to remote peer
+ * This implements [MS-SMBD] 3.1.5.9
+ * The idea is that we should extend credits to remote peer as quickly as
+ * it's allowed, to maintain data flow. We allocate as much receive
+ * buffer as possible, and extend the receive credits to remote peer
+ * return value: the new credtis being granted.
+ */
+static int manage_credits_prior_sending(struct smbd_connection *info)
+{
+       int new_credits;
+
+       spin_lock(&info->lock_new_credits_offered);
+       new_credits = info->new_credits_offered;
+       info->new_credits_offered = 0;
+       spin_unlock(&info->lock_new_credits_offered);
+
+       return new_credits;
+}
+
+/*
+ * Check if we need to send a KEEP_ALIVE message
+ * The idle connection timer triggers a KEEP_ALIVE message when expires
+ * SMB_DIRECT_RESPONSE_REQUESTED is set in the message flag to have peer send
+ * back a response.
+ * return value:
+ * 1 if SMB_DIRECT_RESPONSE_REQUESTED needs to be set
+ * 0: otherwise
+ */
+static int manage_keep_alive_before_sending(struct smbd_connection *info)
+{
+       if (info->keep_alive_requested == KEEP_ALIVE_PENDING) {
+               info->keep_alive_requested = KEEP_ALIVE_SENT;
+               return 1;
+       }
+       return 0;
+}
+
+/*
+ * Build and prepare the SMBD packet header
+ * This function waits for avaialbe send credits and build a SMBD packet
+ * header. The caller then optional append payload to the packet after
+ * the header
+ * intput values
+ * size: the size of the payload
+ * remaining_data_length: remaining data to send if this is part of a
+ * fragmented packet
+ * output values
+ * request_out: the request allocated from this function
+ * return values: 0 on success, otherwise actual error code returned
+ */
+static int smbd_create_header(struct smbd_connection *info,
+               int size, int remaining_data_length,
+               struct smbd_request **request_out)
+{
+       struct smbd_request *request;
+       struct smbd_data_transfer *packet;
+       int header_length;
+       int rc;
+
+       /* Wait for send credits. A SMBD packet needs one credit */
+       rc = wait_event_interruptible(info->wait_send_queue,
+               atomic_read(&info->send_credits) > 0 ||
+               info->transport_status != SMBD_CONNECTED);
+       if (rc)
+               return rc;
+
+       if (info->transport_status != SMBD_CONNECTED) {
+               log_outgoing(ERR, "disconnected not sending\n");
+               return -ENOENT;
+       }
+       atomic_dec(&info->send_credits);
+
+       request = mempool_alloc(info->request_mempool, GFP_KERNEL);
+       if (!request) {
+               rc = -ENOMEM;
+               goto err;
+       }
+
+       request->info = info;
+
+       /* Fill in the packet header */
+       packet = smbd_request_payload(request);
+       packet->credits_requested = cpu_to_le16(info->send_credit_target);
+       packet->credits_granted =
+               cpu_to_le16(manage_credits_prior_sending(info));
+       info->send_immediate = false;
+
+       packet->flags = 0;
+       if (manage_keep_alive_before_sending(info))
+               packet->flags |= cpu_to_le16(SMB_DIRECT_RESPONSE_REQUESTED);
+
+       packet->reserved = 0;
+       if (!size)
+               packet->data_offset = 0;
+       else
+               packet->data_offset = cpu_to_le32(24);
+       packet->data_length = cpu_to_le32(size);
+       packet->remaining_data_length = cpu_to_le32(remaining_data_length);
+       packet->padding = 0;
+
+       log_outgoing(INFO, "credits_requested=%d credits_granted=%d "
+               "data_offset=%d data_length=%d remaining_data_length=%d\n",
+               le16_to_cpu(packet->credits_requested),
+               le16_to_cpu(packet->credits_granted),
+               le32_to_cpu(packet->data_offset),
+               le32_to_cpu(packet->data_length),
+               le32_to_cpu(packet->remaining_data_length));
+
+       /* Map the packet to DMA */
+       header_length = sizeof(struct smbd_data_transfer);
+       /* If this is a packet without payload, don't send padding */
+       if (!size)
+               header_length = offsetof(struct smbd_data_transfer, padding);
+
+       request->num_sge = 1;
+       request->sge[0].addr = ib_dma_map_single(info->id->device,
+                                                (void *)packet,
+                                                header_length,
+                                                DMA_BIDIRECTIONAL);
+       if (ib_dma_mapping_error(info->id->device, request->sge[0].addr)) {
+               mempool_free(request, info->request_mempool);
+               rc = -EIO;
+               goto err;
+       }
+
+       request->sge[0].length = header_length;
+       request->sge[0].lkey = info->pd->local_dma_lkey;
+
+       *request_out = request;
+       return 0;
+
+err:
+       atomic_inc(&info->send_credits);
+       return rc;
+}
+
+static void smbd_destroy_header(struct smbd_connection *info,
+               struct smbd_request *request)
+{
+
+       ib_dma_unmap_single(info->id->device,
+                           request->sge[0].addr,
+                           request->sge[0].length,
+                           DMA_TO_DEVICE);
+       mempool_free(request, info->request_mempool);
+       atomic_inc(&info->send_credits);
+}
+
+/* Post the send request */
+static int smbd_post_send(struct smbd_connection *info,
+               struct smbd_request *request, bool has_payload)
+{
+       struct ib_send_wr send_wr, *send_wr_fail;
+       int rc, i;
+
+       for (i = 0; i < request->num_sge; i++) {
+               log_rdma_send(INFO,
+                       "rdma_request sge[%d] addr=%llu legnth=%u\n",
+                       i, request->sge[0].addr, request->sge[0].length);
+               ib_dma_sync_single_for_device(
+                       info->id->device,
+                       request->sge[i].addr,
+                       request->sge[i].length,
+                       DMA_TO_DEVICE);
+       }
+
+       request->cqe.done = send_done;
+
+       send_wr.next = NULL;
+       send_wr.wr_cqe = &request->cqe;
+       send_wr.sg_list = request->sge;
+       send_wr.num_sge = request->num_sge;
+       send_wr.opcode = IB_WR_SEND;
+       send_wr.send_flags = IB_SEND_SIGNALED;
+
+       if (has_payload) {
+               request->has_payload = true;
+               atomic_inc(&info->send_payload_pending);
+       } else {
+               request->has_payload = false;
+               atomic_inc(&info->send_pending);
+       }
+
+       rc = ib_post_send(info->id->qp, &send_wr, &send_wr_fail);
+       if (rc) {
+               log_rdma_send(ERR, "ib_post_send failed rc=%d\n", rc);
+               if (has_payload) {
+                       if (atomic_dec_and_test(&info->send_payload_pending))
+                               wake_up(&info->wait_send_payload_pending);
+               } else {
+                       if (atomic_dec_and_test(&info->send_pending))
+                               wake_up(&info->wait_send_pending);
+               }
+       } else
+               /* Reset timer for idle connection after packet is sent */
+               mod_delayed_work(info->workqueue, &info->idle_timer_work,
+                       info->keep_alive_interval*HZ);
+
+       return rc;
+}
+
+static int smbd_post_send_sgl(struct smbd_connection *info,
+       struct scatterlist *sgl, int data_length, int remaining_data_length)
+{
+       int num_sgs;
+       int i, rc;
+       struct smbd_request *request;
+       struct scatterlist *sg;
+
+       rc = smbd_create_header(
+               info, data_length, remaining_data_length, &request);
+       if (rc)
+               return rc;
+
+       num_sgs = sgl ? sg_nents(sgl) : 0;
+       for_each_sg(sgl, sg, num_sgs, i) {
+               request->sge[i+1].addr =
+                       ib_dma_map_page(info->id->device, sg_page(sg),
+                              sg->offset, sg->length, DMA_BIDIRECTIONAL);
+               if (ib_dma_mapping_error(
+                               info->id->device, request->sge[i+1].addr)) {
+                       rc = -EIO;
+                       request->sge[i+1].addr = 0;
+                       goto dma_mapping_failure;
+               }
+               request->sge[i+1].length = sg->length;
+               request->sge[i+1].lkey = info->pd->local_dma_lkey;
+               request->num_sge++;
+       }
+
+       rc = smbd_post_send(info, request, data_length);
+       if (!rc)
+               return 0;
+
+dma_mapping_failure:
+       for (i = 1; i < request->num_sge; i++)
+               if (request->sge[i].addr)
+                       ib_dma_unmap_single(info->id->device,
+                                           request->sge[i].addr,
+                                           request->sge[i].length,
+                                           DMA_TO_DEVICE);
+       smbd_destroy_header(info, request);
+       return rc;
+}
+
+/*
+ * Send an empty message
+ * Empty message is used to extend credits to peer to for keep live
+ * while there is no upper layer payload to send at the time
+ */
+static int smbd_post_send_empty(struct smbd_connection *info)
+{
+       info->count_send_empty++;
+       return smbd_post_send_sgl(info, NULL, 0, 0);
+}
+
+/*
+ * Post a receive request to the transport
+ * The remote peer can only send data when a receive request is posted
+ * The interaction is controlled by send/receive credit system
+ */
+static int smbd_post_recv(
+               struct smbd_connection *info, struct smbd_response *response)
+{
+       struct ib_recv_wr recv_wr, *recv_wr_fail = NULL;
+       int rc = -EIO;
+
+       response->sge.addr = ib_dma_map_single(
+                               info->id->device, response->packet,
+                               info->max_receive_size, DMA_FROM_DEVICE);
+       if (ib_dma_mapping_error(info->id->device, response->sge.addr))
+               return rc;
+
+       response->sge.length = info->max_receive_size;
+       response->sge.lkey = info->pd->local_dma_lkey;
+
+       response->cqe.done = recv_done;
+
+       recv_wr.wr_cqe = &response->cqe;
+       recv_wr.next = NULL;
+       recv_wr.sg_list = &response->sge;
+       recv_wr.num_sge = 1;
+
+       rc = ib_post_recv(info->id->qp, &recv_wr, &recv_wr_fail);
+       if (rc) {
+               ib_dma_unmap_single(info->id->device, response->sge.addr,
+                                   response->sge.length, DMA_FROM_DEVICE);
+
+               log_rdma_recv(ERR, "ib_post_recv failed rc=%d\n", rc);
+       }
+
+       return rc;
+}
+
+/* Perform SMBD negotiate according to [MS-SMBD] 3.1.5.2 */
+static int smbd_negotiate(struct smbd_connection *info)
+{
+       int rc;
+       struct smbd_response *response = get_receive_buffer(info);
+
+       response->type = SMBD_NEGOTIATE_RESP;
+       rc = smbd_post_recv(info, response);
+       log_rdma_event(INFO,
+               "smbd_post_recv rc=%d iov.addr=%llx iov.length=%x "
+               "iov.lkey=%x\n",
+               rc, response->sge.addr,
+               response->sge.length, response->sge.lkey);
+       if (rc)
+               return rc;
+
+       init_completion(&info->negotiate_completion);
+       info->negotiate_done = false;
+       rc = smbd_post_send_negotiate_req(info);
+       if (rc)
+               return rc;
+
+       rc = wait_for_completion_interruptible_timeout(
+               &info->negotiate_completion, SMBD_NEGOTIATE_TIMEOUT * HZ);
+       log_rdma_event(INFO, "wait_for_completion_timeout rc=%d\n", rc);
+
+       if (info->negotiate_done)
+               return 0;
+
+       if (rc == 0)
+               rc = -ETIMEDOUT;
+       else if (rc == -ERESTARTSYS)
+               rc = -EINTR;
+       else
+               rc = -ENOTCONN;
+
+       return rc;
+}
+
+static void put_empty_packet(
+               struct smbd_connection *info, struct smbd_response *response)
+{
+       spin_lock(&info->empty_packet_queue_lock);
+       list_add_tail(&response->list, &info->empty_packet_queue);
+       info->count_empty_packet_queue++;
+       spin_unlock(&info->empty_packet_queue_lock);
+
+       queue_work(info->workqueue, &info->post_send_credits_work);
+}
+
+/*
+ * Implement Connection.FragmentReassemblyBuffer defined in [MS-SMBD] 3.1.1.1
+ * This is a queue for reassembling upper layer payload and present to upper
+ * layer. All the inncoming payload go to the reassembly queue, regardless of
+ * if reassembly is required. The uuper layer code reads from the queue for all
+ * incoming payloads.
+ * Put a received packet to the reassembly queue
+ * response: the packet received
+ * data_length: the size of payload in this packet
+ */
+static void enqueue_reassembly(
+       struct smbd_connection *info,
+       struct smbd_response *response,
+       int data_length)
+{
+       spin_lock(&info->reassembly_queue_lock);
+       list_add_tail(&response->list, &info->reassembly_queue);
+       info->reassembly_queue_length++;
+       /*
+        * Make sure reassembly_data_length is updated after list and
+        * reassembly_queue_length are updated. On the dequeue side
+        * reassembly_data_length is checked without a lock to determine
+        * if reassembly_queue_length and list is up to date
+        */
+       virt_wmb();
+       info->reassembly_data_length += data_length;
+       spin_unlock(&info->reassembly_queue_lock);
+       info->count_reassembly_queue++;
+       info->count_enqueue_reassembly_queue++;
+}
+
+/*
+ * Get the first entry at the front of reassembly queue
+ * Caller is responsible for locking
+ * return value: the first entry if any, NULL if queue is empty
+ */
+static struct smbd_response *_get_first_reassembly(struct smbd_connection *info)
+{
+       struct smbd_response *ret = NULL;
+
+       if (!list_empty(&info->reassembly_queue)) {
+               ret = list_first_entry(
+                       &info->reassembly_queue,
+                       struct smbd_response, list);
+       }
+       return ret;
+}
+
+static struct smbd_response *get_empty_queue_buffer(
+               struct smbd_connection *info)
+{
+       struct smbd_response *ret = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&info->empty_packet_queue_lock, flags);
+       if (!list_empty(&info->empty_packet_queue)) {
+               ret = list_first_entry(
+                       &info->empty_packet_queue,
+                       struct smbd_response, list);
+               list_del(&ret->list);
+               info->count_empty_packet_queue--;
+       }
+       spin_unlock_irqrestore(&info->empty_packet_queue_lock, flags);
+
+       return ret;
+}
+
+/*
+ * Get a receive buffer
+ * For each remote send, we need to post a receive. The receive buffers are
+ * pre-allocated in advance.
+ * return value: the receive buffer, NULL if none is available
+ */
+static struct smbd_response *get_receive_buffer(struct smbd_connection *info)
+{
+       struct smbd_response *ret = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&info->receive_queue_lock, flags);
+       if (!list_empty(&info->receive_queue)) {
+               ret = list_first_entry(
+                       &info->receive_queue,
+                       struct smbd_response, list);
+               list_del(&ret->list);
+               info->count_receive_queue--;
+               info->count_get_receive_buffer++;
+       }
+       spin_unlock_irqrestore(&info->receive_queue_lock, flags);
+
+       return ret;
+}
+
+/*
+ * Return a receive buffer
+ * Upon returning of a receive buffer, we can post new receive and extend
+ * more receive credits to remote peer. This is done immediately after a
+ * receive buffer is returned.
+ */
+static void put_receive_buffer(
+       struct smbd_connection *info, struct smbd_response *response)
+{
+       unsigned long flags;
+
+       ib_dma_unmap_single(info->id->device, response->sge.addr,
+               response->sge.length, DMA_FROM_DEVICE);
+
+       spin_lock_irqsave(&info->receive_queue_lock, flags);
+       list_add_tail(&response->list, &info->receive_queue);
+       info->count_receive_queue++;
+       info->count_put_receive_buffer++;
+       spin_unlock_irqrestore(&info->receive_queue_lock, flags);
+
+       queue_work(info->workqueue, &info->post_send_credits_work);
+}
+
+/* Preallocate all receive buffer on transport establishment */
+static int allocate_receive_buffers(struct smbd_connection *info, int num_buf)
+{
+       int i;
+       struct smbd_response *response;
+
+       INIT_LIST_HEAD(&info->reassembly_queue);
+       spin_lock_init(&info->reassembly_queue_lock);
+       info->reassembly_data_length = 0;
+       info->reassembly_queue_length = 0;
+
+       INIT_LIST_HEAD(&info->receive_queue);
+       spin_lock_init(&info->receive_queue_lock);
+       info->count_receive_queue = 0;
+
+       INIT_LIST_HEAD(&info->empty_packet_queue);
+       spin_lock_init(&info->empty_packet_queue_lock);
+       info->count_empty_packet_queue = 0;
+
+       init_waitqueue_head(&info->wait_receive_queues);
+
+       for (i = 0; i < num_buf; i++) {
+               response = mempool_alloc(info->response_mempool, GFP_KERNEL);
+               if (!response)
+                       goto allocate_failed;
+
+               response->info = info;
+               list_add_tail(&response->list, &info->receive_queue);
+               info->count_receive_queue++;
+       }
+
+       return 0;
+
+allocate_failed:
+       while (!list_empty(&info->receive_queue)) {
+               response = list_first_entry(
+                               &info->receive_queue,
+                               struct smbd_response, list);
+               list_del(&response->list);
+               info->count_receive_queue--;
+
+               mempool_free(response, info->response_mempool);
+       }
+       return -ENOMEM;
+}
+
+static void destroy_receive_buffers(struct smbd_connection *info)
+{
+       struct smbd_response *response;
+
+       while ((response = get_receive_buffer(info)))
+               mempool_free(response, info->response_mempool);
+
+       while ((response = get_empty_queue_buffer(info)))
+               mempool_free(response, info->response_mempool);
+}
+
+/*
+ * Check and send an immediate or keep alive packet
+ * The condition to send those packets are defined in [MS-SMBD] 3.1.1.1
+ * Connection.KeepaliveRequested and Connection.SendImmediate
+ * The idea is to extend credits to server as soon as it becomes available
+ */
+static void send_immediate_work(struct work_struct *work)
+{
+       struct smbd_connection *info = container_of(
+                                       work, struct smbd_connection,
+                                       send_immediate_work.work);
+
+       if (info->keep_alive_requested == KEEP_ALIVE_PENDING ||
+           info->send_immediate) {
+               log_keep_alive(INFO, "send an empty message\n");
+               smbd_post_send_empty(info);
+       }
+}
+
+/* Implement idle connection timer [MS-SMBD] 3.1.6.2 */
+static void idle_connection_timer(struct work_struct *work)
+{
+       struct smbd_connection *info = container_of(
+                                       work, struct smbd_connection,
+                                       idle_timer_work.work);
+
+       if (info->keep_alive_requested != KEEP_ALIVE_NONE) {
+               log_keep_alive(ERR,
+                       "error status info->keep_alive_requested=%d\n",
+                       info->keep_alive_requested);
+               smbd_disconnect_rdma_connection(info);
+               return;
+       }
+
+       log_keep_alive(INFO, "about to send an empty idle message\n");
+       smbd_post_send_empty(info);
+
+       /* Setup the next idle timeout work */
+       queue_delayed_work(info->workqueue, &info->idle_timer_work,
+                       info->keep_alive_interval*HZ);
+}
+
+static void destroy_caches_and_workqueue(struct smbd_connection *info)
+{
+       destroy_receive_buffers(info);
+       destroy_workqueue(info->workqueue);
+       mempool_destroy(info->response_mempool);
+       kmem_cache_destroy(info->response_cache);
+       mempool_destroy(info->request_mempool);
+       kmem_cache_destroy(info->request_cache);
+}
+
+#define MAX_NAME_LEN   80
+static int allocate_caches_and_workqueue(struct smbd_connection *info)
+{
+       char name[MAX_NAME_LEN];
+       int rc;
+
+       snprintf(name, MAX_NAME_LEN, "smbd_request_%p", info);
+       info->request_cache =
+               kmem_cache_create(
+                       name,
+                       sizeof(struct smbd_request) +
+                               sizeof(struct smbd_data_transfer),
+                       0, SLAB_HWCACHE_ALIGN, NULL);
+       if (!info->request_cache)
+               return -ENOMEM;
+
+       info->request_mempool =
+               mempool_create(info->send_credit_target, mempool_alloc_slab,
+                       mempool_free_slab, info->request_cache);
+       if (!info->request_mempool)
+               goto out1;
+
+       snprintf(name, MAX_NAME_LEN, "smbd_response_%p", info);
+       info->response_cache =
+               kmem_cache_create(
+                       name,
+                       sizeof(struct smbd_response) +
+                               info->max_receive_size,
+                       0, SLAB_HWCACHE_ALIGN, NULL);
+       if (!info->response_cache)
+               goto out2;
+
+       info->response_mempool =
+               mempool_create(info->receive_credit_max, mempool_alloc_slab,
+                      mempool_free_slab, info->response_cache);
+       if (!info->response_mempool)
+               goto out3;
+
+       snprintf(name, MAX_NAME_LEN, "smbd_%p", info);
+       info->workqueue = create_workqueue(name);
+       if (!info->workqueue)
+               goto out4;
+
+       rc = allocate_receive_buffers(info, info->receive_credit_max);
+       if (rc) {
+               log_rdma_event(ERR, "failed to allocate receive buffers\n");
+               goto out5;
+       }
+
+       return 0;
+
+out5:
+       destroy_workqueue(info->workqueue);
+out4:
+       mempool_destroy(info->response_mempool);
+out3:
+       kmem_cache_destroy(info->response_cache);
+out2:
+       mempool_destroy(info->request_mempool);
+out1:
+       kmem_cache_destroy(info->request_cache);
+       return -ENOMEM;
+}
+
+/* Create a SMBD connection, called by upper layer */
+struct smbd_connection *_smbd_get_connection(
+       struct TCP_Server_Info *server, struct sockaddr *dstaddr, int port)
+{
+       int rc;
+       struct smbd_connection *info;
+       struct rdma_conn_param conn_param;
+       struct ib_qp_init_attr qp_attr;
+       struct sockaddr_in *addr_in = (struct sockaddr_in *) dstaddr;
+
+       info = kzalloc(sizeof(struct smbd_connection), GFP_KERNEL);
+       if (!info)
+               return NULL;
+
+       info->transport_status = SMBD_CONNECTING;
+       rc = smbd_ia_open(info, dstaddr, port);
+       if (rc) {
+               log_rdma_event(INFO, "smbd_ia_open rc=%d\n", rc);
+               goto create_id_failed;
+       }
+
+       if (smbd_send_credit_target > info->id->device->attrs.max_cqe ||
+           smbd_send_credit_target > info->id->device->attrs.max_qp_wr) {
+               log_rdma_event(ERR,
+                       "consider lowering send_credit_target = %d. "
+                       "Possible CQE overrun, device "
+                       "reporting max_cpe %d max_qp_wr %d\n",
+                       smbd_send_credit_target,
+                       info->id->device->attrs.max_cqe,
+                       info->id->device->attrs.max_qp_wr);
+               goto config_failed;
+       }
+
+       if (smbd_receive_credit_max > info->id->device->attrs.max_cqe ||
+           smbd_receive_credit_max > info->id->device->attrs.max_qp_wr) {
+               log_rdma_event(ERR,
+                       "consider lowering receive_credit_max = %d. "
+                       "Possible CQE overrun, device "
+                       "reporting max_cpe %d max_qp_wr %d\n",
+                       smbd_receive_credit_max,
+                       info->id->device->attrs.max_cqe,
+                       info->id->device->attrs.max_qp_wr);
+               goto config_failed;
+       }
+
+       info->receive_credit_max = smbd_receive_credit_max;
+       info->send_credit_target = smbd_send_credit_target;
+       info->max_send_size = smbd_max_send_size;
+       info->max_fragmented_recv_size = smbd_max_fragmented_recv_size;
+       info->max_receive_size = smbd_max_receive_size;
+       info->keep_alive_interval = smbd_keep_alive_interval;
+
+       if (info->id->device->attrs.max_sge < SMBDIRECT_MAX_SGE) {
+               log_rdma_event(ERR, "warning: device max_sge = %d too small\n",
+                       info->id->device->attrs.max_sge);
+               log_rdma_event(ERR, "Queue Pair creation may fail\n");
+       }
+
+       info->send_cq = NULL;
+       info->recv_cq = NULL;
+       info->send_cq = ib_alloc_cq(info->id->device, info,
+                       info->send_credit_target, 0, IB_POLL_SOFTIRQ);
+       if (IS_ERR(info->send_cq)) {
+               info->send_cq = NULL;
+               goto alloc_cq_failed;
+       }
+
+       info->recv_cq = ib_alloc_cq(info->id->device, info,
+                       info->receive_credit_max, 0, IB_POLL_SOFTIRQ);
+       if (IS_ERR(info->recv_cq)) {
+               info->recv_cq = NULL;
+               goto alloc_cq_failed;
+       }
+
+       memset(&qp_attr, 0, sizeof(qp_attr));
+       qp_attr.event_handler = smbd_qp_async_error_upcall;
+       qp_attr.qp_context = info;
+       qp_attr.cap.max_send_wr = info->send_credit_target;
+       qp_attr.cap.max_recv_wr = info->receive_credit_max;
+       qp_attr.cap.max_send_sge = SMBDIRECT_MAX_SGE;
+       qp_attr.cap.max_recv_sge = SMBDIRECT_MAX_SGE;
+       qp_attr.cap.max_inline_data = 0;
+       qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
+       qp_attr.qp_type = IB_QPT_RC;
+       qp_attr.send_cq = info->send_cq;
+       qp_attr.recv_cq = info->recv_cq;
+       qp_attr.port_num = ~0;
+
+       rc = rdma_create_qp(info->id, info->pd, &qp_attr);
+       if (rc) {
+               log_rdma_event(ERR, "rdma_create_qp failed %i\n", rc);
+               goto create_qp_failed;
+       }
+
+       memset(&conn_param, 0, sizeof(conn_param));
+       conn_param.initiator_depth = 0;
+
+       conn_param.retry_count = SMBD_CM_RETRY;
+       conn_param.rnr_retry_count = SMBD_CM_RNR_RETRY;
+       conn_param.flow_control = 0;
+       init_waitqueue_head(&info->wait_destroy);
+
+       log_rdma_event(INFO, "connecting to IP %pI4 port %d\n",
+               &addr_in->sin_addr, port);
+
+       init_waitqueue_head(&info->conn_wait);
+       rc = rdma_connect(info->id, &conn_param);
+       if (rc) {
+               log_rdma_event(ERR, "rdma_connect() failed with %i\n", rc);
+               goto rdma_connect_failed;
+       }
+
+       wait_event_interruptible(
+               info->conn_wait, info->transport_status != SMBD_CONNECTING);
+
+       if (info->transport_status != SMBD_CONNECTED) {
+               log_rdma_event(ERR, "rdma_connect failed port=%d\n", port);
+               goto rdma_connect_failed;
+       }
+
+       log_rdma_event(INFO, "rdma_connect connected\n");
+
+       rc = allocate_caches_and_workqueue(info);
+       if (rc) {
+               log_rdma_event(ERR, "cache allocation failed\n");
+               goto allocate_cache_failed;
+       }
+
+       init_waitqueue_head(&info->wait_send_queue);
+       init_waitqueue_head(&info->wait_reassembly_queue);
+
+       INIT_DELAYED_WORK(&info->idle_timer_work, idle_connection_timer);
+       INIT_DELAYED_WORK(&info->send_immediate_work, send_immediate_work);
+       queue_delayed_work(info->workqueue, &info->idle_timer_work,
+               info->keep_alive_interval*HZ);
+
+       init_waitqueue_head(&info->wait_send_pending);
+       atomic_set(&info->send_pending, 0);
+
+       init_waitqueue_head(&info->wait_send_payload_pending);
+       atomic_set(&info->send_payload_pending, 0);
+
+       INIT_WORK(&info->disconnect_work, smbd_disconnect_rdma_work);
+       INIT_WORK(&info->destroy_work, smbd_destroy_rdma_work);
+       INIT_WORK(&info->recv_done_work, smbd_recv_done_work);
+       INIT_WORK(&info->post_send_credits_work, smbd_post_send_credits);
+       info->new_credits_offered = 0;
+       spin_lock_init(&info->lock_new_credits_offered);
+
+       rc = smbd_negotiate(info);
+       if (rc) {
+               log_rdma_event(ERR, "smbd_negotiate rc=%d\n", rc);
+               goto negotiation_failed;
+       }
+
+       return info;
+
+negotiation_failed:
+       cancel_delayed_work_sync(&info->idle_timer_work);
+       destroy_caches_and_workqueue(info);
+       info->transport_status = SMBD_NEGOTIATE_FAILED;
+       init_waitqueue_head(&info->conn_wait);
+       rdma_disconnect(info->id);
+       wait_event(info->conn_wait,
+               info->transport_status == SMBD_DISCONNECTED);
+
+allocate_cache_failed:
+rdma_connect_failed:
+       rdma_destroy_qp(info->id);
+
+create_qp_failed:
+alloc_cq_failed:
+       if (info->send_cq)
+               ib_free_cq(info->send_cq);
+       if (info->recv_cq)
+               ib_free_cq(info->recv_cq);
+
+config_failed:
+       ib_dealloc_pd(info->pd);
+       rdma_destroy_id(info->id);
+
+create_id_failed:
+       kfree(info);
+       return NULL;
+}