RDMA/rtrs: server: main functionality
authorJack Wang <jinpu.wang@cloud.ionos.com>
Mon, 11 May 2020 13:51:16 +0000 (15:51 +0200)
committerJason Gunthorpe <jgg@mellanox.com>
Sun, 17 May 2020 21:57:14 +0000 (18:57 -0300)
This is main functionality of rtrs-server module, which accepts set of
RDMA connections (so called rtrs session), creates/destroys sysfs entries
associated with rtrs session and notifies upper layer
(user of RTRS API) about RDMA requests or link events.

Link: https://lore.kernel.org/r/20200511135131.27580-11-danil.kipnis@cloud.ionos.com
Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
drivers/infiniband/ulp/rtrs/rtrs-srv.c [new file with mode: 0644]

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
new file mode 100644 (file)
index 0000000..ba8ab33
--- /dev/null
@@ -0,0 +1,2175 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RDMA Transport Layer
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
+ */
+
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include <linux/module.h>
+#include <linux/mempool.h>
+
+#include "rtrs-srv.h"
+#include "rtrs-log.h"
+
+MODULE_DESCRIPTION("RDMA Transport Server");
+MODULE_LICENSE("GPL");
+
+/* Must be power of 2, see mask from mr->page_size in ib_sg_to_pages() */
+#define DEFAULT_MAX_CHUNK_SIZE (128 << 10)
+#define DEFAULT_SESS_QUEUE_DEPTH 512
+#define MAX_HDR_SIZE PAGE_SIZE
+
+/* We guarantee to serve 10 paths at least */
+#define CHUNK_POOL_SZ 10
+
+static struct rtrs_rdma_dev_pd dev_pd;
+static mempool_t *chunk_pool;
+struct class *rtrs_dev_class;
+
+static int __read_mostly max_chunk_size = DEFAULT_MAX_CHUNK_SIZE;
+static int __read_mostly sess_queue_depth = DEFAULT_SESS_QUEUE_DEPTH;
+
+static bool always_invalidate = true;
+module_param(always_invalidate, bool, 0444);
+MODULE_PARM_DESC(always_invalidate,
+                "Invalidate memory registration for contiguous memory regions before accessing.");
+
+module_param_named(max_chunk_size, max_chunk_size, int, 0444);
+MODULE_PARM_DESC(max_chunk_size,
+                "Max size for each IO request, when change the unit is in byte (default: "
+                __stringify(DEFAULT_MAX_CHUNK_SIZE) "KB)");
+
+module_param_named(sess_queue_depth, sess_queue_depth, int, 0444);
+MODULE_PARM_DESC(sess_queue_depth,
+                "Number of buffers for pending I/O requests to allocate per session. Maximum: "
+                __stringify(MAX_SESS_QUEUE_DEPTH) " (default: "
+                __stringify(DEFAULT_SESS_QUEUE_DEPTH) ")");
+
+static cpumask_t cq_affinity_mask = { CPU_BITS_ALL };
+
+static struct workqueue_struct *rtrs_wq;
+
+static inline struct rtrs_srv_con *to_srv_con(struct rtrs_con *c)
+{
+       return container_of(c, struct rtrs_srv_con, c);
+}
+
+static inline struct rtrs_srv_sess *to_srv_sess(struct rtrs_sess *s)
+{
+       return container_of(s, struct rtrs_srv_sess, s);
+}
+
+static bool __rtrs_srv_change_state(struct rtrs_srv_sess *sess,
+                                    enum rtrs_srv_state new_state)
+{
+       enum rtrs_srv_state old_state;
+       bool changed = false;
+
+       lockdep_assert_held(&sess->state_lock);
+       old_state = sess->state;
+       switch (new_state) {
+       case RTRS_SRV_CONNECTED:
+               switch (old_state) {
+               case RTRS_SRV_CONNECTING:
+                       changed = true;
+                       fallthrough;
+               default:
+                       break;
+               }
+               break;
+       case RTRS_SRV_CLOSING:
+               switch (old_state) {
+               case RTRS_SRV_CONNECTING:
+               case RTRS_SRV_CONNECTED:
+                       changed = true;
+                       fallthrough;
+               default:
+                       break;
+               }
+               break;
+       case RTRS_SRV_CLOSED:
+               switch (old_state) {
+               case RTRS_SRV_CLOSING:
+                       changed = true;
+                       fallthrough;
+               default:
+                       break;
+               }
+               break;
+       default:
+               break;
+       }
+       if (changed)
+               sess->state = new_state;
+
+       return changed;
+}
+
+static bool rtrs_srv_change_state_get_old(struct rtrs_srv_sess *sess,
+                                          enum rtrs_srv_state new_state,
+                                          enum rtrs_srv_state *old_state)
+{
+       bool changed;
+
+       spin_lock_irq(&sess->state_lock);
+       *old_state = sess->state;
+       changed = __rtrs_srv_change_state(sess, new_state);
+       spin_unlock_irq(&sess->state_lock);
+
+       return changed;
+}
+
+static bool rtrs_srv_change_state(struct rtrs_srv_sess *sess,
+                                  enum rtrs_srv_state new_state)
+{
+       enum rtrs_srv_state old_state;
+
+       return rtrs_srv_change_state_get_old(sess, new_state, &old_state);
+}
+
+static void free_id(struct rtrs_srv_op *id)
+{
+       if (!id)
+               return;
+       kfree(id);
+}
+
+static void rtrs_srv_free_ops_ids(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+       int i;
+
+       WARN_ON(atomic_read(&sess->ids_inflight));
+       if (sess->ops_ids) {
+               for (i = 0; i < srv->queue_depth; i++)
+                       free_id(sess->ops_ids[i]);
+               kfree(sess->ops_ids);
+               sess->ops_ids = NULL;
+       }
+}
+
+static void rtrs_srv_rdma_done(struct ib_cq *cq, struct ib_wc *wc);
+
+static struct ib_cqe io_comp_cqe = {
+       .done = rtrs_srv_rdma_done
+};
+
+static int rtrs_srv_alloc_ops_ids(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_srv_op *id;
+       int i;
+
+       sess->ops_ids = kcalloc(srv->queue_depth, sizeof(*sess->ops_ids),
+                               GFP_KERNEL);
+       if (!sess->ops_ids)
+               goto err;
+
+       for (i = 0; i < srv->queue_depth; ++i) {
+               id = kzalloc(sizeof(*id), GFP_KERNEL);
+               if (!id)
+                       goto err;
+
+               sess->ops_ids[i] = id;
+       }
+       init_waitqueue_head(&sess->ids_waitq);
+       atomic_set(&sess->ids_inflight, 0);
+
+       return 0;
+
+err:
+       rtrs_srv_free_ops_ids(sess);
+       return -ENOMEM;
+}
+
+static inline void rtrs_srv_get_ops_ids(struct rtrs_srv_sess *sess)
+{
+       atomic_inc(&sess->ids_inflight);
+}
+
+static inline void rtrs_srv_put_ops_ids(struct rtrs_srv_sess *sess)
+{
+       if (atomic_dec_and_test(&sess->ids_inflight))
+               wake_up(&sess->ids_waitq);
+}
+
+static void rtrs_srv_wait_ops_ids(struct rtrs_srv_sess *sess)
+{
+       wait_event(sess->ids_waitq, !atomic_read(&sess->ids_inflight));
+}
+
+
+static void rtrs_srv_reg_mr_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       struct rtrs_srv_con *con = cq->cq_context;
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+
+       if (unlikely(wc->status != IB_WC_SUCCESS)) {
+               rtrs_err(s, "REG MR failed: %s\n",
+                         ib_wc_status_msg(wc->status));
+               close_sess(sess);
+               return;
+       }
+}
+
+static struct ib_cqe local_reg_cqe = {
+       .done = rtrs_srv_reg_mr_done
+};
+
+static int rdma_write_sg(struct rtrs_srv_op *id)
+{
+       struct rtrs_sess *s = id->con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       dma_addr_t dma_addr = sess->dma_addr[id->msg_id];
+       struct rtrs_srv_mr *srv_mr;
+       struct rtrs_srv *srv = sess->srv;
+       struct ib_send_wr inv_wr, imm_wr;
+       struct ib_rdma_wr *wr = NULL;
+       enum ib_send_flags flags;
+       size_t sg_cnt;
+       int err, offset;
+       bool need_inval;
+       u32 rkey = 0;
+       struct ib_reg_wr rwr;
+       struct ib_sge *plist;
+       struct ib_sge list;
+
+       sg_cnt = le16_to_cpu(id->rd_msg->sg_cnt);
+       need_inval = le16_to_cpu(id->rd_msg->flags) & RTRS_MSG_NEED_INVAL_F;
+       if (unlikely(sg_cnt != 1))
+               return -EINVAL;
+
+       offset = 0;
+
+       wr              = &id->tx_wr;
+       plist           = &id->tx_sg;
+       plist->addr     = dma_addr + offset;
+       plist->length   = le32_to_cpu(id->rd_msg->desc[0].len);
+
+       /* WR will fail with length error
+        * if this is 0
+        */
+       if (unlikely(plist->length == 0)) {
+               rtrs_err(s, "Invalid RDMA-Write sg list length 0\n");
+               return -EINVAL;
+       }
+
+       plist->lkey = sess->s.dev->ib_pd->local_dma_lkey;
+       offset += plist->length;
+
+       wr->wr.sg_list  = plist;
+       wr->wr.num_sge  = 1;
+       wr->remote_addr = le64_to_cpu(id->rd_msg->desc[0].addr);
+       wr->rkey        = le32_to_cpu(id->rd_msg->desc[0].key);
+       if (rkey == 0)
+               rkey = wr->rkey;
+       else
+               /* Only one key is actually used */
+               WARN_ON_ONCE(rkey != wr->rkey);
+
+       wr->wr.opcode = IB_WR_RDMA_WRITE;
+       wr->wr.ex.imm_data = 0;
+       wr->wr.send_flags  = 0;
+
+       if (need_inval && always_invalidate) {
+               wr->wr.next = &rwr.wr;
+               rwr.wr.next = &inv_wr;
+               inv_wr.next = &imm_wr;
+       } else if (always_invalidate) {
+               wr->wr.next = &rwr.wr;
+               rwr.wr.next = &imm_wr;
+       } else if (need_inval) {
+               wr->wr.next = &inv_wr;
+               inv_wr.next = &imm_wr;
+       } else {
+               wr->wr.next = &imm_wr;
+       }
+       /*
+        * From time to time we have to post signaled sends,
+        * or send queue will fill up and only QP reset can help.
+        */
+       flags = (atomic_inc_return(&id->con->wr_cnt) % srv->queue_depth) ?
+               0 : IB_SEND_SIGNALED;
+
+       if (need_inval) {
+               inv_wr.sg_list = NULL;
+               inv_wr.num_sge = 0;
+               inv_wr.opcode = IB_WR_SEND_WITH_INV;
+               inv_wr.send_flags = 0;
+               inv_wr.ex.invalidate_rkey = rkey;
+       }
+
+       imm_wr.next = NULL;
+       if (always_invalidate) {
+               struct rtrs_msg_rkey_rsp *msg;
+
+               srv_mr = &sess->mrs[id->msg_id];
+               rwr.wr.opcode = IB_WR_REG_MR;
+               rwr.wr.num_sge = 0;
+               rwr.mr = srv_mr->mr;
+               rwr.wr.send_flags = 0;
+               rwr.key = srv_mr->mr->rkey;
+               rwr.access = (IB_ACCESS_LOCAL_WRITE |
+                             IB_ACCESS_REMOTE_WRITE);
+               msg = srv_mr->iu->buf;
+               msg->buf_id = cpu_to_le16(id->msg_id);
+               msg->type = cpu_to_le16(RTRS_MSG_RKEY_RSP);
+               msg->rkey = cpu_to_le32(srv_mr->mr->rkey);
+
+               list.addr   = srv_mr->iu->dma_addr;
+               list.length = sizeof(*msg);
+               list.lkey   = sess->s.dev->ib_pd->local_dma_lkey;
+               imm_wr.sg_list = &list;
+               imm_wr.num_sge = 1;
+               imm_wr.opcode = IB_WR_SEND_WITH_IMM;
+               ib_dma_sync_single_for_device(sess->s.dev->ib_dev,
+                                             srv_mr->iu->dma_addr,
+                                             srv_mr->iu->size, DMA_TO_DEVICE);
+       } else {
+               imm_wr.sg_list = NULL;
+               imm_wr.num_sge = 0;
+               imm_wr.opcode = IB_WR_RDMA_WRITE_WITH_IMM;
+       }
+       imm_wr.send_flags = flags;
+       imm_wr.ex.imm_data = cpu_to_be32(rtrs_to_io_rsp_imm(id->msg_id,
+                                                            0, need_inval));
+
+       imm_wr.wr_cqe   = &io_comp_cqe;
+       ib_dma_sync_single_for_device(sess->s.dev->ib_dev, dma_addr,
+                                     offset, DMA_BIDIRECTIONAL);
+
+       err = ib_post_send(id->con->c.qp, &id->tx_wr.wr, NULL);
+       if (unlikely(err))
+               rtrs_err(s,
+                         "Posting RDMA-Write-Request to QP failed, err: %d\n",
+                         err);
+
+       return err;
+}
+
+/**
+ * send_io_resp_imm() - respond to client with empty IMM on failed READ/WRITE
+ *                      requests or on successful WRITE request.
+ * @con:       the connection to send back result
+ * @id:                the id associated with the IO
+ * @errno:     the error number of the IO.
+ *
+ * Return 0 on success, errno otherwise.
+ */
+static int send_io_resp_imm(struct rtrs_srv_con *con, struct rtrs_srv_op *id,
+                           int errno)
+{
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct ib_send_wr inv_wr, imm_wr, *wr = NULL;
+       struct ib_reg_wr rwr;
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_srv_mr *srv_mr;
+       bool need_inval = false;
+       enum ib_send_flags flags;
+       u32 imm;
+       int err;
+
+       if (id->dir == READ) {
+               struct rtrs_msg_rdma_read *rd_msg = id->rd_msg;
+               size_t sg_cnt;
+
+               need_inval = le16_to_cpu(rd_msg->flags) &
+                               RTRS_MSG_NEED_INVAL_F;
+               sg_cnt = le16_to_cpu(rd_msg->sg_cnt);
+
+               if (need_inval) {
+                       if (likely(sg_cnt)) {
+                               inv_wr.sg_list = NULL;
+                               inv_wr.num_sge = 0;
+                               inv_wr.opcode = IB_WR_SEND_WITH_INV;
+                               inv_wr.send_flags = 0;
+                               /* Only one key is actually used */
+                               inv_wr.ex.invalidate_rkey =
+                                       le32_to_cpu(rd_msg->desc[0].key);
+                       } else {
+                               WARN_ON_ONCE(1);
+                               need_inval = false;
+                       }
+               }
+       }
+
+       if (need_inval && always_invalidate) {
+               wr = &inv_wr;
+               inv_wr.next = &rwr.wr;
+               rwr.wr.next = &imm_wr;
+       } else if (always_invalidate) {
+               wr = &rwr.wr;
+               rwr.wr.next = &imm_wr;
+       } else if (need_inval) {
+               wr = &inv_wr;
+               inv_wr.next = &imm_wr;
+       } else {
+               wr = &imm_wr;
+       }
+       /*
+        * From time to time we have to post signalled sends,
+        * or send queue will fill up and only QP reset can help.
+        */
+       flags = (atomic_inc_return(&con->wr_cnt) % srv->queue_depth) ?
+               0 : IB_SEND_SIGNALED;
+       imm = rtrs_to_io_rsp_imm(id->msg_id, errno, need_inval);
+       imm_wr.next = NULL;
+       if (always_invalidate) {
+               struct ib_sge list;
+               struct rtrs_msg_rkey_rsp *msg;
+
+               srv_mr = &sess->mrs[id->msg_id];
+               rwr.wr.next = &imm_wr;
+               rwr.wr.opcode = IB_WR_REG_MR;
+               rwr.wr.num_sge = 0;
+               rwr.wr.send_flags = 0;
+               rwr.mr = srv_mr->mr;
+               rwr.key = srv_mr->mr->rkey;
+               rwr.access = (IB_ACCESS_LOCAL_WRITE |
+                             IB_ACCESS_REMOTE_WRITE);
+               msg = srv_mr->iu->buf;
+               msg->buf_id = cpu_to_le16(id->msg_id);
+               msg->type = cpu_to_le16(RTRS_MSG_RKEY_RSP);
+               msg->rkey = cpu_to_le32(srv_mr->mr->rkey);
+
+               list.addr   = srv_mr->iu->dma_addr;
+               list.length = sizeof(*msg);
+               list.lkey   = sess->s.dev->ib_pd->local_dma_lkey;
+               imm_wr.sg_list = &list;
+               imm_wr.num_sge = 1;
+               imm_wr.opcode = IB_WR_SEND_WITH_IMM;
+               ib_dma_sync_single_for_device(sess->s.dev->ib_dev,
+                                             srv_mr->iu->dma_addr,
+                                             srv_mr->iu->size, DMA_TO_DEVICE);
+       } else {
+               imm_wr.sg_list = NULL;
+               imm_wr.num_sge = 0;
+               imm_wr.opcode = IB_WR_RDMA_WRITE_WITH_IMM;
+       }
+       imm_wr.send_flags = flags;
+       imm_wr.wr_cqe   = &io_comp_cqe;
+
+       imm_wr.ex.imm_data = cpu_to_be32(imm);
+
+       err = ib_post_send(id->con->c.qp, wr, NULL);
+       if (unlikely(err))
+               rtrs_err_rl(s, "Posting RDMA-Reply to QP failed, err: %d\n",
+                            err);
+
+       return err;
+}
+
+void close_sess(struct rtrs_srv_sess *sess)
+{
+       enum rtrs_srv_state old_state;
+
+       if (rtrs_srv_change_state_get_old(sess, RTRS_SRV_CLOSING,
+                                          &old_state))
+               queue_work(rtrs_wq, &sess->close_work);
+       WARN_ON(sess->state != RTRS_SRV_CLOSING);
+}
+
+static inline const char *rtrs_srv_state_str(enum rtrs_srv_state state)
+{
+       switch (state) {
+       case RTRS_SRV_CONNECTING:
+               return "RTRS_SRV_CONNECTING";
+       case RTRS_SRV_CONNECTED:
+               return "RTRS_SRV_CONNECTED";
+       case RTRS_SRV_CLOSING:
+               return "RTRS_SRV_CLOSING";
+       case RTRS_SRV_CLOSED:
+               return "RTRS_SRV_CLOSED";
+       default:
+               return "UNKNOWN";
+       }
+}
+
+/**
+ * rtrs_srv_resp_rdma() - Finish an RDMA request
+ *
+ * @id:                Internal RTRS operation identifier
+ * @status:    Response Code sent to the other side for this operation.
+ *             0 = success, <=0 error
+ * Context: any
+ *
+ * Finish a RDMA operation. A message is sent to the client and the
+ * corresponding memory areas will be released.
+ */
+bool rtrs_srv_resp_rdma(struct rtrs_srv_op *id, int status)
+{
+       struct rtrs_srv_sess *sess;
+       struct rtrs_srv_con *con;
+       struct rtrs_sess *s;
+       int err;
+
+       if (WARN_ON(!id))
+               return true;
+
+       con = id->con;
+       s = con->c.sess;
+       sess = to_srv_sess(s);
+
+       id->status = status;
+
+       if (unlikely(sess->state != RTRS_SRV_CONNECTED)) {
+               rtrs_err_rl(s,
+                            "Sending I/O response failed,  session is disconnected, sess state %s\n",
+                            rtrs_srv_state_str(sess->state));
+               goto out;
+       }
+       if (always_invalidate) {
+               struct rtrs_srv_mr *mr = &sess->mrs[id->msg_id];
+
+               ib_update_fast_reg_key(mr->mr, ib_inc_rkey(mr->mr->rkey));
+       }
+       if (unlikely(atomic_sub_return(1,
+                                      &con->sq_wr_avail) < 0)) {
+               pr_err("IB send queue full\n");
+               atomic_add(1, &con->sq_wr_avail);
+               spin_lock(&con->rsp_wr_wait_lock);
+               list_add_tail(&id->wait_list, &con->rsp_wr_wait_list);
+               spin_unlock(&con->rsp_wr_wait_lock);
+               return false;
+       }
+
+       if (status || id->dir == WRITE || !id->rd_msg->sg_cnt)
+               err = send_io_resp_imm(con, id, status);
+       else
+               err = rdma_write_sg(id);
+
+       if (unlikely(err)) {
+               rtrs_err_rl(s, "IO response failed: %d\n", err);
+               close_sess(sess);
+       }
+out:
+       rtrs_srv_put_ops_ids(sess);
+       return true;
+}
+EXPORT_SYMBOL(rtrs_srv_resp_rdma);
+
+/**
+ * rtrs_srv_set_sess_priv() - Set private pointer in rtrs_srv.
+ * @srv:       Session pointer
+ * @priv:      The private pointer that is associated with the session.
+ */
+void rtrs_srv_set_sess_priv(struct rtrs_srv *srv, void *priv)
+{
+       srv->priv = priv;
+}
+EXPORT_SYMBOL(rtrs_srv_set_sess_priv);
+
+static void unmap_cont_bufs(struct rtrs_srv_sess *sess)
+{
+       int i;
+
+       for (i = 0; i < sess->mrs_num; i++) {
+               struct rtrs_srv_mr *srv_mr;
+
+               srv_mr = &sess->mrs[i];
+               rtrs_iu_free(srv_mr->iu, DMA_TO_DEVICE,
+                             sess->s.dev->ib_dev, 1);
+               ib_dereg_mr(srv_mr->mr);
+               ib_dma_unmap_sg(sess->s.dev->ib_dev, srv_mr->sgt.sgl,
+                               srv_mr->sgt.nents, DMA_BIDIRECTIONAL);
+               sg_free_table(&srv_mr->sgt);
+       }
+       kfree(sess->mrs);
+}
+
+static int map_cont_bufs(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_sess *ss = &sess->s;
+       int i, mri, err, mrs_num;
+       unsigned int chunk_bits;
+       int chunks_per_mr = 1;
+
+       /*
+        * Here we map queue_depth chunks to MR.  Firstly we have to
+        * figure out how many chunks can we map per MR.
+        */
+       if (always_invalidate) {
+               /*
+                * in order to do invalidate for each chunks of memory, we needs
+                * more memory regions.
+                */
+               mrs_num = srv->queue_depth;
+       } else {
+               chunks_per_mr =
+                       sess->s.dev->ib_dev->attrs.max_fast_reg_page_list_len;
+               mrs_num = DIV_ROUND_UP(srv->queue_depth, chunks_per_mr);
+               chunks_per_mr = DIV_ROUND_UP(srv->queue_depth, mrs_num);
+       }
+
+       sess->mrs = kcalloc(mrs_num, sizeof(*sess->mrs), GFP_KERNEL);
+       if (!sess->mrs)
+               return -ENOMEM;
+
+       sess->mrs_num = mrs_num;
+
+       for (mri = 0; mri < mrs_num; mri++) {
+               struct rtrs_srv_mr *srv_mr = &sess->mrs[mri];
+               struct sg_table *sgt = &srv_mr->sgt;
+               struct scatterlist *s;
+               struct ib_mr *mr;
+               int nr, chunks;
+
+               chunks = chunks_per_mr * mri;
+               if (!always_invalidate)
+                       chunks_per_mr = min_t(int, chunks_per_mr,
+                                             srv->queue_depth - chunks);
+
+               err = sg_alloc_table(sgt, chunks_per_mr, GFP_KERNEL);
+               if (err)
+                       goto err;
+
+               for_each_sg(sgt->sgl, s, chunks_per_mr, i)
+                       sg_set_page(s, srv->chunks[chunks + i],
+                                   max_chunk_size, 0);
+
+               nr = ib_dma_map_sg(sess->s.dev->ib_dev, sgt->sgl,
+                                  sgt->nents, DMA_BIDIRECTIONAL);
+               if (nr < sgt->nents) {
+                       err = nr < 0 ? nr : -EINVAL;
+                       goto free_sg;
+               }
+               mr = ib_alloc_mr(sess->s.dev->ib_pd, IB_MR_TYPE_MEM_REG,
+                                sgt->nents);
+               if (IS_ERR(mr)) {
+                       err = PTR_ERR(mr);
+                       goto unmap_sg;
+               }
+               nr = ib_map_mr_sg(mr, sgt->sgl, sgt->nents,
+                                 NULL, max_chunk_size);
+               if (nr < sgt->nents) {
+                       err = nr < 0 ? nr : -EINVAL;
+                       goto dereg_mr;
+               }
+
+               if (always_invalidate) {
+                       srv_mr->iu = rtrs_iu_alloc(1,
+                                       sizeof(struct rtrs_msg_rkey_rsp),
+                                       GFP_KERNEL, sess->s.dev->ib_dev,
+                                       DMA_TO_DEVICE, rtrs_srv_rdma_done);
+                       if (!srv_mr->iu) {
+                               rtrs_err(ss, "rtrs_iu_alloc(), err: %d\n",
+                                         -ENOMEM);
+                               goto free_iu;
+                       }
+               }
+               /* Eventually dma addr for each chunk can be cached */
+               for_each_sg(sgt->sgl, s, sgt->orig_nents, i)
+                       sess->dma_addr[chunks + i] = sg_dma_address(s);
+
+               ib_update_fast_reg_key(mr, ib_inc_rkey(mr->rkey));
+               srv_mr->mr = mr;
+
+               continue;
+err:
+               while (mri--) {
+                       srv_mr = &sess->mrs[mri];
+                       sgt = &srv_mr->sgt;
+                       mr = srv_mr->mr;
+free_iu:
+                       rtrs_iu_free(srv_mr->iu, DMA_TO_DEVICE,
+                                     sess->s.dev->ib_dev, 1);
+dereg_mr:
+                       ib_dereg_mr(mr);
+unmap_sg:
+                       ib_dma_unmap_sg(sess->s.dev->ib_dev, sgt->sgl,
+                                       sgt->nents, DMA_BIDIRECTIONAL);
+free_sg:
+                       sg_free_table(sgt);
+               }
+               kfree(sess->mrs);
+
+               return err;
+       }
+
+       chunk_bits = ilog2(srv->queue_depth - 1) + 1;
+       sess->mem_bits = (MAX_IMM_PAYL_BITS - chunk_bits);
+
+       return 0;
+}
+
+static void rtrs_srv_hb_err_handler(struct rtrs_con *c)
+{
+       close_sess(to_srv_sess(c->sess));
+}
+
+static void rtrs_srv_init_hb(struct rtrs_srv_sess *sess)
+{
+       rtrs_init_hb(&sess->s, &io_comp_cqe,
+                     RTRS_HB_INTERVAL_MS,
+                     RTRS_HB_MISSED_MAX,
+                     rtrs_srv_hb_err_handler,
+                     rtrs_wq);
+}
+
+static void rtrs_srv_start_hb(struct rtrs_srv_sess *sess)
+{
+       rtrs_start_hb(&sess->s);
+}
+
+static void rtrs_srv_stop_hb(struct rtrs_srv_sess *sess)
+{
+       rtrs_stop_hb(&sess->s);
+}
+
+static void rtrs_srv_info_rsp_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       struct rtrs_srv_con *con = cq->cq_context;
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_iu *iu;
+
+       iu = container_of(wc->wr_cqe, struct rtrs_iu, cqe);
+       rtrs_iu_free(iu, DMA_TO_DEVICE, sess->s.dev->ib_dev, 1);
+
+       if (unlikely(wc->status != IB_WC_SUCCESS)) {
+               rtrs_err(s, "Sess info response send failed: %s\n",
+                         ib_wc_status_msg(wc->status));
+               close_sess(sess);
+               return;
+       }
+       WARN_ON(wc->opcode != IB_WC_SEND);
+}
+
+static void rtrs_srv_sess_up(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_srv_ctx *ctx = srv->ctx;
+       int up;
+
+       mutex_lock(&srv->paths_ev_mutex);
+       up = ++srv->paths_up;
+       if (up == 1)
+               ctx->ops.link_ev(srv, RTRS_SRV_LINK_EV_CONNECTED, NULL);
+       mutex_unlock(&srv->paths_ev_mutex);
+
+       /* Mark session as established */
+       sess->established = true;
+}
+
+static void rtrs_srv_sess_down(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_srv_ctx *ctx = srv->ctx;
+
+       if (!sess->established)
+               return;
+
+       sess->established = false;
+       mutex_lock(&srv->paths_ev_mutex);
+       WARN_ON(!srv->paths_up);
+       if (--srv->paths_up == 0)
+               ctx->ops.link_ev(srv, RTRS_SRV_LINK_EV_DISCONNECTED, srv->priv);
+       mutex_unlock(&srv->paths_ev_mutex);
+}
+
+static int post_recv_sess(struct rtrs_srv_sess *sess);
+
+static int process_info_req(struct rtrs_srv_con *con,
+                           struct rtrs_msg_info_req *msg)
+{
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct ib_send_wr *reg_wr = NULL;
+       struct rtrs_msg_info_rsp *rsp;
+       struct rtrs_iu *tx_iu;
+       struct ib_reg_wr *rwr;
+       int mri, err;
+       size_t tx_sz;
+
+       err = post_recv_sess(sess);
+       if (unlikely(err)) {
+               rtrs_err(s, "post_recv_sess(), err: %d\n", err);
+               return err;
+       }
+       rwr = kcalloc(sess->mrs_num, sizeof(*rwr), GFP_KERNEL);
+       if (unlikely(!rwr))
+               return -ENOMEM;
+       strlcpy(sess->s.sessname, msg->sessname, sizeof(sess->s.sessname));
+
+       tx_sz  = sizeof(*rsp);
+       tx_sz += sizeof(rsp->desc[0]) * sess->mrs_num;
+       tx_iu = rtrs_iu_alloc(1, tx_sz, GFP_KERNEL, sess->s.dev->ib_dev,
+                              DMA_TO_DEVICE, rtrs_srv_info_rsp_done);
+       if (unlikely(!tx_iu)) {
+               err = -ENOMEM;
+               goto rwr_free;
+       }
+
+       rsp = tx_iu->buf;
+       rsp->type = cpu_to_le16(RTRS_MSG_INFO_RSP);
+       rsp->sg_cnt = cpu_to_le16(sess->mrs_num);
+
+       for (mri = 0; mri < sess->mrs_num; mri++) {
+               struct ib_mr *mr = sess->mrs[mri].mr;
+
+               rsp->desc[mri].addr = cpu_to_le64(mr->iova);
+               rsp->desc[mri].key  = cpu_to_le32(mr->rkey);
+               rsp->desc[mri].len  = cpu_to_le32(mr->length);
+
+               /*
+                * Fill in reg MR request and chain them *backwards*
+                */
+               rwr[mri].wr.next = mri ? &rwr[mri - 1].wr : NULL;
+               rwr[mri].wr.opcode = IB_WR_REG_MR;
+               rwr[mri].wr.wr_cqe = &local_reg_cqe;
+               rwr[mri].wr.num_sge = 0;
+               rwr[mri].wr.send_flags = mri ? 0 : IB_SEND_SIGNALED;
+               rwr[mri].mr = mr;
+               rwr[mri].key = mr->rkey;
+               rwr[mri].access = (IB_ACCESS_LOCAL_WRITE |
+                                  IB_ACCESS_REMOTE_WRITE);
+               reg_wr = &rwr[mri].wr;
+       }
+
+       err = rtrs_srv_create_sess_files(sess);
+       if (unlikely(err))
+               goto iu_free;
+       kobject_get(&sess->kobj);
+       get_device(&sess->srv->dev);
+       rtrs_srv_change_state(sess, RTRS_SRV_CONNECTED);
+       rtrs_srv_start_hb(sess);
+
+       /*
+        * We do not account number of established connections at the current
+        * moment, we rely on the client, which should send info request when
+        * all connections are successfully established.  Thus, simply notify
+        * listener with a proper event if we are the first path.
+        */
+       rtrs_srv_sess_up(sess);
+
+       ib_dma_sync_single_for_device(sess->s.dev->ib_dev, tx_iu->dma_addr,
+                                     tx_iu->size, DMA_TO_DEVICE);
+
+       /* Send info response */
+       err = rtrs_iu_post_send(&con->c, tx_iu, tx_sz, reg_wr);
+       if (unlikely(err)) {
+               rtrs_err(s, "rtrs_iu_post_send(), err: %d\n", err);
+iu_free:
+               rtrs_iu_free(tx_iu, DMA_TO_DEVICE, sess->s.dev->ib_dev, 1);
+       }
+rwr_free:
+       kfree(rwr);
+
+       return err;
+}
+
+static void rtrs_srv_info_req_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       struct rtrs_srv_con *con = cq->cq_context;
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_msg_info_req *msg;
+       struct rtrs_iu *iu;
+       int err;
+
+       WARN_ON(con->c.cid);
+
+       iu = container_of(wc->wr_cqe, struct rtrs_iu, cqe);
+       if (unlikely(wc->status != IB_WC_SUCCESS)) {
+               rtrs_err(s, "Sess info request receive failed: %s\n",
+                         ib_wc_status_msg(wc->status));
+               goto close;
+       }
+       WARN_ON(wc->opcode != IB_WC_RECV);
+
+       if (unlikely(wc->byte_len < sizeof(*msg))) {
+               rtrs_err(s, "Sess info request is malformed: size %d\n",
+                         wc->byte_len);
+               goto close;
+       }
+       ib_dma_sync_single_for_cpu(sess->s.dev->ib_dev, iu->dma_addr,
+                                  iu->size, DMA_FROM_DEVICE);
+       msg = iu->buf;
+       if (unlikely(le16_to_cpu(msg->type) != RTRS_MSG_INFO_REQ)) {
+               rtrs_err(s, "Sess info request is malformed: type %d\n",
+                         le16_to_cpu(msg->type));
+               goto close;
+       }
+       err = process_info_req(con, msg);
+       if (unlikely(err))
+               goto close;
+
+out:
+       rtrs_iu_free(iu, DMA_FROM_DEVICE, sess->s.dev->ib_dev, 1);
+       return;
+close:
+       close_sess(sess);
+       goto out;
+}
+
+static int post_recv_info_req(struct rtrs_srv_con *con)
+{
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_iu *rx_iu;
+       int err;
+
+       rx_iu = rtrs_iu_alloc(1, sizeof(struct rtrs_msg_info_req),
+                              GFP_KERNEL, sess->s.dev->ib_dev,
+                              DMA_FROM_DEVICE, rtrs_srv_info_req_done);
+       if (unlikely(!rx_iu))
+               return -ENOMEM;
+       /* Prepare for getting info response */
+       err = rtrs_iu_post_recv(&con->c, rx_iu);
+       if (unlikely(err)) {
+               rtrs_err(s, "rtrs_iu_post_recv(), err: %d\n", err);
+               rtrs_iu_free(rx_iu, DMA_FROM_DEVICE, sess->s.dev->ib_dev, 1);
+               return err;
+       }
+
+       return 0;
+}
+
+static int post_recv_io(struct rtrs_srv_con *con, size_t q_size)
+{
+       int i, err;
+
+       for (i = 0; i < q_size; i++) {
+               err = rtrs_post_recv_empty(&con->c, &io_comp_cqe);
+               if (unlikely(err))
+                       return err;
+       }
+
+       return 0;
+}
+
+static int post_recv_sess(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_sess *s = &sess->s;
+       size_t q_size;
+       int err, cid;
+
+       for (cid = 0; cid < sess->s.con_num; cid++) {
+               if (cid == 0)
+                       q_size = SERVICE_CON_QUEUE_DEPTH;
+               else
+                       q_size = srv->queue_depth;
+
+               err = post_recv_io(to_srv_con(sess->s.con[cid]), q_size);
+               if (unlikely(err)) {
+                       rtrs_err(s, "post_recv_io(), err: %d\n", err);
+                       return err;
+               }
+       }
+
+       return 0;
+}
+
+static void process_read(struct rtrs_srv_con *con,
+                        struct rtrs_msg_rdma_read *msg,
+                        u32 buf_id, u32 off)
+{
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_srv_ctx *ctx = srv->ctx;
+       struct rtrs_srv_op *id;
+
+       size_t usr_len, data_len;
+       void *data;
+       int ret;
+
+       if (unlikely(sess->state != RTRS_SRV_CONNECTED)) {
+               rtrs_err_rl(s,
+                            "Processing read request failed,  session is disconnected, sess state %s\n",
+                            rtrs_srv_state_str(sess->state));
+               return;
+       }
+       if (unlikely(msg->sg_cnt != 1 && msg->sg_cnt != 0)) {
+               rtrs_err_rl(s,
+                           "Processing read request failed, invalid message\n");
+               return;
+       }
+       rtrs_srv_get_ops_ids(sess);
+       rtrs_srv_update_rdma_stats(sess->stats, off, READ);
+       id = sess->ops_ids[buf_id];
+       id->con         = con;
+       id->dir         = READ;
+       id->msg_id      = buf_id;
+       id->rd_msg      = msg;
+       usr_len = le16_to_cpu(msg->usr_len);
+       data_len = off - usr_len;
+       data = page_address(srv->chunks[buf_id]);
+       ret = ctx->ops.rdma_ev(srv, srv->priv, id, READ, data, data_len,
+                          data + data_len, usr_len);
+
+       if (unlikely(ret)) {
+               rtrs_err_rl(s,
+                            "Processing read request failed, user module cb reported for msg_id %d, err: %d\n",
+                            buf_id, ret);
+               goto send_err_msg;
+       }
+
+       return;
+
+send_err_msg:
+       ret = send_io_resp_imm(con, id, ret);
+       if (ret < 0) {
+               rtrs_err_rl(s,
+                            "Sending err msg for failed RDMA-Write-Req failed, msg_id %d, err: %d\n",
+                            buf_id, ret);
+               close_sess(sess);
+       }
+       rtrs_srv_put_ops_ids(sess);
+}
+
+static void process_write(struct rtrs_srv_con *con,
+                         struct rtrs_msg_rdma_write *req,
+                         u32 buf_id, u32 off)
+{
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_srv_ctx *ctx = srv->ctx;
+       struct rtrs_srv_op *id;
+
+       size_t data_len, usr_len;
+       void *data;
+       int ret;
+
+       if (unlikely(sess->state != RTRS_SRV_CONNECTED)) {
+               rtrs_err_rl(s,
+                            "Processing write request failed,  session is disconnected, sess state %s\n",
+                            rtrs_srv_state_str(sess->state));
+               return;
+       }
+       rtrs_srv_get_ops_ids(sess);
+       rtrs_srv_update_rdma_stats(sess->stats, off, WRITE);
+       id = sess->ops_ids[buf_id];
+       id->con    = con;
+       id->dir    = WRITE;
+       id->msg_id = buf_id;
+
+       usr_len = le16_to_cpu(req->usr_len);
+       data_len = off - usr_len;
+       data = page_address(srv->chunks[buf_id]);
+       ret = ctx->ops.rdma_ev(srv, srv->priv, id, WRITE, data, data_len,
+                          data + data_len, usr_len);
+       if (unlikely(ret)) {
+               rtrs_err_rl(s,
+                            "Processing write request failed, user module callback reports err: %d\n",
+                            ret);
+               goto send_err_msg;
+       }
+
+       return;
+
+send_err_msg:
+       ret = send_io_resp_imm(con, id, ret);
+       if (ret < 0) {
+               rtrs_err_rl(s,
+                            "Processing write request failed, sending I/O response failed, msg_id %d, err: %d\n",
+                            buf_id, ret);
+               close_sess(sess);
+       }
+       rtrs_srv_put_ops_ids(sess);
+}
+
+static void process_io_req(struct rtrs_srv_con *con, void *msg,
+                          u32 id, u32 off)
+{
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_msg_rdma_hdr *hdr;
+       unsigned int type;
+
+       ib_dma_sync_single_for_cpu(sess->s.dev->ib_dev, sess->dma_addr[id],
+                                  max_chunk_size, DMA_BIDIRECTIONAL);
+       hdr = msg;
+       type = le16_to_cpu(hdr->type);
+
+       switch (type) {
+       case RTRS_MSG_WRITE:
+               process_write(con, msg, id, off);
+               break;
+       case RTRS_MSG_READ:
+               process_read(con, msg, id, off);
+               break;
+       default:
+               rtrs_err(s,
+                         "Processing I/O request failed, unknown message type received: 0x%02x\n",
+                         type);
+               goto err;
+       }
+
+       return;
+
+err:
+       close_sess(sess);
+}
+
+static void rtrs_srv_inv_rkey_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       struct rtrs_srv_mr *mr =
+               container_of(wc->wr_cqe, typeof(*mr), inv_cqe);
+       struct rtrs_srv_con *con = cq->cq_context;
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_srv *srv = sess->srv;
+       u32 msg_id, off;
+       void *data;
+
+       if (unlikely(wc->status != IB_WC_SUCCESS)) {
+               rtrs_err(s, "Failed IB_WR_LOCAL_INV: %s\n",
+                         ib_wc_status_msg(wc->status));
+               close_sess(sess);
+       }
+       msg_id = mr->msg_id;
+       off = mr->msg_off;
+       data = page_address(srv->chunks[msg_id]) + off;
+       process_io_req(con, data, msg_id, off);
+}
+
+static int rtrs_srv_inv_rkey(struct rtrs_srv_con *con,
+                             struct rtrs_srv_mr *mr)
+{
+       struct ib_send_wr wr = {
+               .opcode             = IB_WR_LOCAL_INV,
+               .wr_cqe             = &mr->inv_cqe,
+               .send_flags         = IB_SEND_SIGNALED,
+               .ex.invalidate_rkey = mr->mr->rkey,
+       };
+       mr->inv_cqe.done = rtrs_srv_inv_rkey_done;
+
+       return ib_post_send(con->c.qp, &wr, NULL);
+}
+
+static void rtrs_rdma_process_wr_wait_list(struct rtrs_srv_con *con)
+{
+       spin_lock(&con->rsp_wr_wait_lock);
+       while (!list_empty(&con->rsp_wr_wait_list)) {
+               struct rtrs_srv_op *id;
+               int ret;
+
+               id = list_entry(con->rsp_wr_wait_list.next,
+                               struct rtrs_srv_op, wait_list);
+               list_del(&id->wait_list);
+
+               spin_unlock(&con->rsp_wr_wait_lock);
+               ret = rtrs_srv_resp_rdma(id, id->status);
+               spin_lock(&con->rsp_wr_wait_lock);
+
+               if (!ret) {
+                       list_add(&id->wait_list, &con->rsp_wr_wait_list);
+                       break;
+               }
+       }
+       spin_unlock(&con->rsp_wr_wait_lock);
+}
+
+static void rtrs_srv_rdma_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+       struct rtrs_srv_con *con = cq->cq_context;
+       struct rtrs_sess *s = con->c.sess;
+       struct rtrs_srv_sess *sess = to_srv_sess(s);
+       struct rtrs_srv *srv = sess->srv;
+       u32 imm_type, imm_payload;
+       int err;
+
+       if (unlikely(wc->status != IB_WC_SUCCESS)) {
+               if (wc->status != IB_WC_WR_FLUSH_ERR) {
+                       rtrs_err(s,
+                                 "%s (wr_cqe: %p, type: %d, vendor_err: 0x%x, len: %u)\n",
+                                 ib_wc_status_msg(wc->status), wc->wr_cqe,
+                                 wc->opcode, wc->vendor_err, wc->byte_len);
+                       close_sess(sess);
+               }
+               return;
+       }
+
+       switch (wc->opcode) {
+       case IB_WC_RECV_RDMA_WITH_IMM:
+               /*
+                * post_recv() RDMA write completions of IO reqs (read/write)
+                * and hb
+                */
+               if (WARN_ON(wc->wr_cqe != &io_comp_cqe))
+                       return;
+               err = rtrs_post_recv_empty(&con->c, &io_comp_cqe);
+               if (unlikely(err)) {
+                       rtrs_err(s, "rtrs_post_recv(), err: %d\n", err);
+                       close_sess(sess);
+                       break;
+               }
+               rtrs_from_imm(be32_to_cpu(wc->ex.imm_data),
+                              &imm_type, &imm_payload);
+               if (likely(imm_type == RTRS_IO_REQ_IMM)) {
+                       u32 msg_id, off;
+                       void *data;
+
+                       msg_id = imm_payload >> sess->mem_bits;
+                       off = imm_payload & ((1 << sess->mem_bits) - 1);
+                       if (unlikely(msg_id > srv->queue_depth ||
+                                    off > max_chunk_size)) {
+                               rtrs_err(s, "Wrong msg_id %u, off %u\n",
+                                         msg_id, off);
+                               close_sess(sess);
+                               return;
+                       }
+                       if (always_invalidate) {
+                               struct rtrs_srv_mr *mr = &sess->mrs[msg_id];
+
+                               mr->msg_off = off;
+                               mr->msg_id = msg_id;
+                               err = rtrs_srv_inv_rkey(con, mr);
+                               if (unlikely(err)) {
+                                       rtrs_err(s, "rtrs_post_recv(), err: %d\n",
+                                                 err);
+                                       close_sess(sess);
+                                       break;
+                               }
+                       } else {
+                               data = page_address(srv->chunks[msg_id]) + off;
+                               process_io_req(con, data, msg_id, off);
+                       }
+               } else if (imm_type == RTRS_HB_MSG_IMM) {
+                       WARN_ON(con->c.cid);
+                       rtrs_send_hb_ack(&sess->s);
+               } else if (imm_type == RTRS_HB_ACK_IMM) {
+                       WARN_ON(con->c.cid);
+                       sess->s.hb_missed_cnt = 0;
+               } else {
+                       rtrs_wrn(s, "Unknown IMM type %u\n", imm_type);
+               }
+               break;
+       case IB_WC_RDMA_WRITE:
+       case IB_WC_SEND:
+               /*
+                * post_send() RDMA write completions of IO reqs (read/write)
+                * and hb
+                */
+               atomic_add(srv->queue_depth, &con->sq_wr_avail);
+
+               if (unlikely(!list_empty_careful(&con->rsp_wr_wait_list)))
+                       rtrs_rdma_process_wr_wait_list(con);
+
+               break;
+       default:
+               rtrs_wrn(s, "Unexpected WC type: %d\n", wc->opcode);
+               return;
+       }
+}
+
+/**
+ * rtrs_srv_get_sess_name() - Get rtrs_srv peer hostname.
+ * @srv:       Session
+ * @sessname:  Sessname buffer
+ * @len:       Length of sessname buffer
+ */
+int rtrs_srv_get_sess_name(struct rtrs_srv *srv, char *sessname, size_t len)
+{
+       struct rtrs_srv_sess *sess;
+       int err = -ENOTCONN;
+
+       mutex_lock(&srv->paths_mutex);
+       list_for_each_entry(sess, &srv->paths_list, s.entry) {
+               if (sess->state != RTRS_SRV_CONNECTED)
+                       continue;
+               strlcpy(sessname, sess->s.sessname,
+                      min_t(size_t, sizeof(sess->s.sessname), len));
+               err = 0;
+               break;
+       }
+       mutex_unlock(&srv->paths_mutex);
+
+       return err;
+}
+EXPORT_SYMBOL(rtrs_srv_get_sess_name);
+
+/**
+ * rtrs_srv_get_sess_qdepth() - Get rtrs_srv qdepth.
+ * @srv:       Session
+ */
+int rtrs_srv_get_queue_depth(struct rtrs_srv *srv)
+{
+       return srv->queue_depth;
+}
+EXPORT_SYMBOL(rtrs_srv_get_queue_depth);
+
+static int find_next_bit_ring(struct rtrs_srv_sess *sess)
+{
+       struct ib_device *ib_dev = sess->s.dev->ib_dev;
+       int v;
+
+       v = cpumask_next(sess->cur_cq_vector, &cq_affinity_mask);
+       if (v >= nr_cpu_ids || v >= ib_dev->num_comp_vectors)
+               v = cpumask_first(&cq_affinity_mask);
+       return v;
+}
+
+static int rtrs_srv_get_next_cq_vector(struct rtrs_srv_sess *sess)
+{
+       sess->cur_cq_vector = find_next_bit_ring(sess);
+
+       return sess->cur_cq_vector;
+}
+
+static struct rtrs_srv *__alloc_srv(struct rtrs_srv_ctx *ctx,
+                                    const uuid_t *paths_uuid)
+{
+       struct rtrs_srv *srv;
+       int i;
+
+       srv = kzalloc(sizeof(*srv), GFP_KERNEL);
+       if  (!srv)
+               return NULL;
+
+       refcount_set(&srv->refcount, 1);
+       INIT_LIST_HEAD(&srv->paths_list);
+       mutex_init(&srv->paths_mutex);
+       mutex_init(&srv->paths_ev_mutex);
+       uuid_copy(&srv->paths_uuid, paths_uuid);
+       srv->queue_depth = sess_queue_depth;
+       srv->ctx = ctx;
+
+       srv->chunks = kcalloc(srv->queue_depth, sizeof(*srv->chunks),
+                             GFP_KERNEL);
+       if (!srv->chunks)
+               goto err_free_srv;
+
+       for (i = 0; i < srv->queue_depth; i++) {
+               srv->chunks[i] = mempool_alloc(chunk_pool, GFP_KERNEL);
+               if (!srv->chunks[i])
+                       goto err_free_chunks;
+       }
+       list_add(&srv->ctx_list, &ctx->srv_list);
+
+       return srv;
+
+err_free_chunks:
+       while (i--)
+               mempool_free(srv->chunks[i], chunk_pool);
+       kfree(srv->chunks);
+
+err_free_srv:
+       kfree(srv);
+
+       return NULL;
+}
+
+static void free_srv(struct rtrs_srv *srv)
+{
+       int i;
+
+       WARN_ON(refcount_read(&srv->refcount));
+       for (i = 0; i < srv->queue_depth; i++)
+               mempool_free(srv->chunks[i], chunk_pool);
+       kfree(srv->chunks);
+       mutex_destroy(&srv->paths_mutex);
+       mutex_destroy(&srv->paths_ev_mutex);
+       /* last put to release the srv structure */
+       put_device(&srv->dev);
+}
+
+static inline struct rtrs_srv *__find_srv_and_get(struct rtrs_srv_ctx *ctx,
+                                                  const uuid_t *paths_uuid)
+{
+       struct rtrs_srv *srv;
+
+       list_for_each_entry(srv, &ctx->srv_list, ctx_list) {
+               if (uuid_equal(&srv->paths_uuid, paths_uuid) &&
+                   refcount_inc_not_zero(&srv->refcount))
+                       return srv;
+       }
+
+       return NULL;
+}
+
+static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
+                                          const uuid_t *paths_uuid)
+{
+       struct rtrs_srv *srv;
+
+       mutex_lock(&ctx->srv_mutex);
+       srv = __find_srv_and_get(ctx, paths_uuid);
+       if (!srv)
+               srv = __alloc_srv(ctx, paths_uuid);
+       mutex_unlock(&ctx->srv_mutex);
+
+       return srv;
+}
+
+static void put_srv(struct rtrs_srv *srv)
+{
+       if (refcount_dec_and_test(&srv->refcount)) {
+               struct rtrs_srv_ctx *ctx = srv->ctx;
+
+               WARN_ON(srv->dev.kobj.state_in_sysfs);
+
+               mutex_lock(&ctx->srv_mutex);
+               list_del(&srv->ctx_list);
+               mutex_unlock(&ctx->srv_mutex);
+               free_srv(srv);
+       }
+}
+
+static void __add_path_to_srv(struct rtrs_srv *srv,
+                             struct rtrs_srv_sess *sess)
+{
+       list_add_tail(&sess->s.entry, &srv->paths_list);
+       srv->paths_num++;
+       WARN_ON(srv->paths_num >= MAX_PATHS_NUM);
+}
+
+static void del_path_from_srv(struct rtrs_srv_sess *sess)
+{
+       struct rtrs_srv *srv = sess->srv;
+
+       if (WARN_ON(!srv))
+               return;
+
+       mutex_lock(&srv->paths_mutex);
+       list_del(&sess->s.entry);
+       WARN_ON(!srv->paths_num);
+       srv->paths_num--;
+       mutex_unlock(&srv->paths_mutex);
+}
+
+/* return true if addresses are the same, error other wise */
+static int sockaddr_cmp(const struct sockaddr *a, const struct sockaddr *b)
+{
+       switch (a->sa_family) {
+       case AF_IB:
+               return memcmp(&((struct sockaddr_ib *)a)->sib_addr,
+                             &((struct sockaddr_ib *)b)->sib_addr,
+                             sizeof(struct ib_addr)) &&
+                       (b->sa_family == AF_IB);
+       case AF_INET:
+               return memcmp(&((struct sockaddr_in *)a)->sin_addr,
+                             &((struct sockaddr_in *)b)->sin_addr,
+                             sizeof(struct in_addr)) &&
+                       (b->sa_family == AF_INET);
+       case AF_INET6:
+               return memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
+                             &((struct sockaddr_in6 *)b)->sin6_addr,
+                             sizeof(struct in6_addr)) &&
+                       (b->sa_family == AF_INET6);
+       default:
+               return -ENOENT;
+       }
+}
+
+static bool __is_path_w_addr_exists(struct rtrs_srv *srv,
+                                   struct rdma_addr *addr)
+{
+       struct rtrs_srv_sess *sess;
+
+       list_for_each_entry(sess, &srv->paths_list, s.entry)
+               if (!sockaddr_cmp((struct sockaddr *)&sess->s.dst_addr,
+                                 (struct sockaddr *)&addr->dst_addr) &&
+                   !sockaddr_cmp((struct sockaddr *)&sess->s.src_addr,
+                                 (struct sockaddr *)&addr->src_addr))
+                       return true;
+
+       return false;
+}
+
+static void free_sess(struct rtrs_srv_sess *sess)
+{
+       if (sess->kobj.state_in_sysfs)
+               kobject_put(&sess->kobj);
+       else
+               kfree(sess);
+}
+
+static void rtrs_srv_close_work(struct work_struct *work)
+{
+       struct rtrs_srv_sess *sess;
+       struct rtrs_srv_con *con;
+       int i;
+
+       sess = container_of(work, typeof(*sess), close_work);
+
+       rtrs_srv_destroy_sess_files(sess);
+       rtrs_srv_stop_hb(sess);
+
+       for (i = 0; i < sess->s.con_num; i++) {
+               if (!sess->s.con[i])
+                       continue;
+               con = to_srv_con(sess->s.con[i]);
+               rdma_disconnect(con->c.cm_id);
+               ib_drain_qp(con->c.qp);
+       }
+       /* Wait for all inflights */
+       rtrs_srv_wait_ops_ids(sess);
+
+       /* Notify upper layer if we are the last path */
+       rtrs_srv_sess_down(sess);
+
+       unmap_cont_bufs(sess);
+       rtrs_srv_free_ops_ids(sess);
+
+       for (i = 0; i < sess->s.con_num; i++) {
+               if (!sess->s.con[i])
+                       continue;
+               con = to_srv_con(sess->s.con[i]);
+               rtrs_cq_qp_destroy(&con->c);
+               rdma_destroy_id(con->c.cm_id);
+               kfree(con);
+       }
+       rtrs_ib_dev_put(sess->s.dev);
+
+       del_path_from_srv(sess);
+       put_srv(sess->srv);
+       sess->srv = NULL;
+       rtrs_srv_change_state(sess, RTRS_SRV_CLOSED);
+
+       kfree(sess->dma_addr);
+       kfree(sess->s.con);
+       free_sess(sess);
+}
+
+static int rtrs_rdma_do_accept(struct rtrs_srv_sess *sess,
+                              struct rdma_cm_id *cm_id)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_msg_conn_rsp msg;
+       struct rdma_conn_param param;
+       int err;
+
+       param = (struct rdma_conn_param) {
+               .rnr_retry_count = 7,
+               .private_data = &msg,
+               .private_data_len = sizeof(msg),
+       };
+
+       msg = (struct rtrs_msg_conn_rsp) {
+               .magic = cpu_to_le16(RTRS_MAGIC),
+               .version = cpu_to_le16(RTRS_PROTO_VER),
+               .queue_depth = cpu_to_le16(srv->queue_depth),
+               .max_io_size = cpu_to_le32(max_chunk_size - MAX_HDR_SIZE),
+               .max_hdr_size = cpu_to_le32(MAX_HDR_SIZE),
+       };
+
+       if (always_invalidate)
+               msg.flags = cpu_to_le32(RTRS_MSG_NEW_RKEY_F);
+
+       err = rdma_accept(cm_id, &param);
+       if (err)
+               pr_err("rdma_accept(), err: %d\n", err);
+
+       return err;
+}
+
+static int rtrs_rdma_do_reject(struct rdma_cm_id *cm_id, int errno)
+{
+       struct rtrs_msg_conn_rsp msg;
+       int err;
+
+       msg = (struct rtrs_msg_conn_rsp) {
+               .magic = cpu_to_le16(RTRS_MAGIC),
+               .version = cpu_to_le16(RTRS_PROTO_VER),
+               .errno = cpu_to_le16(errno),
+       };
+
+       err = rdma_reject(cm_id, &msg, sizeof(msg));
+       if (err)
+               pr_err("rdma_reject(), err: %d\n", err);
+
+       /* Bounce errno back */
+       return errno;
+}
+
+static struct rtrs_srv_sess *
+__find_sess(struct rtrs_srv *srv, const uuid_t *sess_uuid)
+{
+       struct rtrs_srv_sess *sess;
+
+       list_for_each_entry(sess, &srv->paths_list, s.entry) {
+               if (uuid_equal(&sess->s.uuid, sess_uuid))
+                       return sess;
+       }
+
+       return NULL;
+}
+
+static int create_con(struct rtrs_srv_sess *sess,
+                     struct rdma_cm_id *cm_id,
+                     unsigned int cid)
+{
+       struct rtrs_srv *srv = sess->srv;
+       struct rtrs_sess *s = &sess->s;
+       struct rtrs_srv_con *con;
+
+       u16 cq_size, wr_queue_size;
+       int err, cq_vector;
+
+       con = kzalloc(sizeof(*con), GFP_KERNEL);
+       if (!con) {
+               err = -ENOMEM;
+               goto err;
+       }
+
+       spin_lock_init(&con->rsp_wr_wait_lock);
+       INIT_LIST_HEAD(&con->rsp_wr_wait_list);
+       con->c.cm_id = cm_id;
+       con->c.sess = &sess->s;
+       con->c.cid = cid;
+       atomic_set(&con->wr_cnt, 0);
+
+       if (con->c.cid == 0) {
+               /*
+                * All receive and all send (each requiring invalidate)
+                * + 2 for drain and heartbeat
+                */
+               wr_queue_size = SERVICE_CON_QUEUE_DEPTH * 3 + 2;
+               cq_size = wr_queue_size;
+       } else {
+               /*
+                * If we have all receive requests posted and
+                * all write requests posted and each read request
+                * requires an invalidate request + drain
+                * and qp gets into error state.
+                */
+               cq_size = srv->queue_depth * 3 + 1;
+               /*
+                * In theory we might have queue_depth * 32
+                * outstanding requests if an unsafe global key is used
+                * and we have queue_depth read requests each consisting
+                * of 32 different addresses. div 3 for mlx5.
+                */
+               wr_queue_size = sess->s.dev->ib_dev->attrs.max_qp_wr / 3;
+       }
+       atomic_set(&con->sq_wr_avail, wr_queue_size);
+       cq_vector = rtrs_srv_get_next_cq_vector(sess);
+
+       /* TODO: SOFTIRQ can be faster, but be careful with softirq context */
+       err = rtrs_cq_qp_create(&sess->s, &con->c, 1, cq_vector, cq_size,
+                                wr_queue_size, IB_POLL_WORKQUEUE);
+       if (err) {
+               rtrs_err(s, "rtrs_cq_qp_create(), err: %d\n", err);
+               goto free_con;
+       }
+       if (con->c.cid == 0) {
+               err = post_recv_info_req(con);
+               if (err)
+                       goto free_cqqp;
+       }
+       WARN_ON(sess->s.con[cid]);
+       sess->s.con[cid] = &con->c;
+
+       /*
+        * Change context from server to current connection.  The other
+        * way is to use cm_id->qp->qp_context, which does not work on OFED.
+        */
+       cm_id->context = &con->c;
+
+       return 0;
+
+free_cqqp:
+       rtrs_cq_qp_destroy(&con->c);
+free_con:
+       kfree(con);
+
+err:
+       return err;
+}
+
+static struct rtrs_srv_sess *__alloc_sess(struct rtrs_srv *srv,
+                                          struct rdma_cm_id *cm_id,
+                                          unsigned int con_num,
+                                          unsigned int recon_cnt,
+                                          const uuid_t *uuid)
+{
+       struct rtrs_srv_sess *sess;
+       int err = -ENOMEM;
+
+       if (srv->paths_num >= MAX_PATHS_NUM) {
+               err = -ECONNRESET;
+               goto err;
+       }
+       if (__is_path_w_addr_exists(srv, &cm_id->route.addr)) {
+               err = -EEXIST;
+               pr_err("Path with same addr exists\n");
+               goto err;
+       }
+       sess = kzalloc(sizeof(*sess), GFP_KERNEL);
+       if (!sess)
+               goto err;
+
+       sess->stats = kzalloc(sizeof(*sess->stats), GFP_KERNEL);
+       if (!sess->stats)
+               goto err_free_sess;
+
+       sess->stats->sess = sess;
+
+       sess->dma_addr = kcalloc(srv->queue_depth, sizeof(*sess->dma_addr),
+                                GFP_KERNEL);
+       if (!sess->dma_addr)
+               goto err_free_stats;
+
+       sess->s.con = kcalloc(con_num, sizeof(*sess->s.con), GFP_KERNEL);
+       if (!sess->s.con)
+               goto err_free_dma_addr;
+
+       sess->state = RTRS_SRV_CONNECTING;
+       sess->srv = srv;
+       sess->cur_cq_vector = -1;
+       sess->s.dst_addr = cm_id->route.addr.dst_addr;
+       sess->s.src_addr = cm_id->route.addr.src_addr;
+       sess->s.con_num = con_num;
+       sess->s.recon_cnt = recon_cnt;
+       uuid_copy(&sess->s.uuid, uuid);
+       spin_lock_init(&sess->state_lock);
+       INIT_WORK(&sess->close_work, rtrs_srv_close_work);
+       rtrs_srv_init_hb(sess);
+
+       sess->s.dev = rtrs_ib_dev_find_or_add(cm_id->device, &dev_pd);
+       if (!sess->s.dev) {
+               err = -ENOMEM;
+               goto err_free_con;
+       }
+       err = map_cont_bufs(sess);
+       if (err)
+               goto err_put_dev;
+
+       err = rtrs_srv_alloc_ops_ids(sess);
+       if (err)
+               goto err_unmap_bufs;
+
+       __add_path_to_srv(srv, sess);
+
+       return sess;
+
+err_unmap_bufs:
+       unmap_cont_bufs(sess);
+err_put_dev:
+       rtrs_ib_dev_put(sess->s.dev);
+err_free_con:
+       kfree(sess->s.con);
+err_free_dma_addr:
+       kfree(sess->dma_addr);
+err_free_stats:
+       kfree(sess->stats);
+err_free_sess:
+       kfree(sess);
+err:
+       return ERR_PTR(err);
+}
+
+static int rtrs_rdma_connect(struct rdma_cm_id *cm_id,
+                             const struct rtrs_msg_conn_req *msg,
+                             size_t len)
+{
+       struct rtrs_srv_ctx *ctx = cm_id->context;
+       struct rtrs_srv_sess *sess;
+       struct rtrs_srv *srv;
+
+       u16 version, con_num, cid;
+       u16 recon_cnt;
+       int err;
+
+       if (len < sizeof(*msg)) {
+               pr_err("Invalid RTRS connection request\n");
+               goto reject_w_econnreset;
+       }
+       if (le16_to_cpu(msg->magic) != RTRS_MAGIC) {
+               pr_err("Invalid RTRS magic\n");
+               goto reject_w_econnreset;
+       }
+       version = le16_to_cpu(msg->version);
+       if (version >> 8 != RTRS_PROTO_VER_MAJOR) {
+               pr_err("Unsupported major RTRS version: %d, expected %d\n",
+                      version >> 8, RTRS_PROTO_VER_MAJOR);
+               goto reject_w_econnreset;
+       }
+       con_num = le16_to_cpu(msg->cid_num);
+       if (con_num > 4096) {
+               /* Sanity check */
+               pr_err("Too many connections requested: %d\n", con_num);
+               goto reject_w_econnreset;
+       }
+       cid = le16_to_cpu(msg->cid);
+       if (cid >= con_num) {
+               /* Sanity check */
+               pr_err("Incorrect cid: %d >= %d\n", cid, con_num);
+               goto reject_w_econnreset;
+       }
+       recon_cnt = le16_to_cpu(msg->recon_cnt);
+       srv = get_or_create_srv(ctx, &msg->paths_uuid);
+       if (!srv) {
+               err = -ENOMEM;
+               goto reject_w_err;
+       }
+       mutex_lock(&srv->paths_mutex);
+       sess = __find_sess(srv, &msg->sess_uuid);
+       if (sess) {
+               struct rtrs_sess *s = &sess->s;
+
+               /* Session already holds a reference */
+               put_srv(srv);
+
+               if (sess->state != RTRS_SRV_CONNECTING) {
+                       rtrs_err(s, "Session in wrong state: %s\n",
+                                 rtrs_srv_state_str(sess->state));
+                       mutex_unlock(&srv->paths_mutex);
+                       goto reject_w_econnreset;
+               }
+               /*
+                * Sanity checks
+                */
+               if (con_num != sess->s.con_num || cid >= sess->s.con_num) {
+                       rtrs_err(s, "Incorrect request: %d, %d\n",
+                                 cid, con_num);
+                       mutex_unlock(&srv->paths_mutex);
+                       goto reject_w_econnreset;
+               }
+               if (sess->s.con[cid]) {
+                       rtrs_err(s, "Connection already exists: %d\n",
+                                 cid);
+                       mutex_unlock(&srv->paths_mutex);
+                       goto reject_w_econnreset;
+               }
+       } else {
+               sess = __alloc_sess(srv, cm_id, con_num, recon_cnt,
+                                   &msg->sess_uuid);
+               if (IS_ERR(sess)) {
+                       mutex_unlock(&srv->paths_mutex);
+                       put_srv(srv);
+                       err = PTR_ERR(sess);
+                       goto reject_w_err;
+               }
+       }
+       err = create_con(sess, cm_id, cid);
+       if (err) {
+               (void)rtrs_rdma_do_reject(cm_id, err);
+               /*
+                * Since session has other connections we follow normal way
+                * through workqueue, but still return an error to tell cma.c
+                * to call rdma_destroy_id() for current connection.
+                */
+               goto close_and_return_err;
+       }
+       err = rtrs_rdma_do_accept(sess, cm_id);
+       if (err) {
+               (void)rtrs_rdma_do_reject(cm_id, err);
+               /*
+                * Since current connection was successfully added to the
+                * session we follow normal way through workqueue to close the
+                * session, thus return 0 to tell cma.c we call
+                * rdma_destroy_id() ourselves.
+                */
+               err = 0;
+               goto close_and_return_err;
+       }
+       mutex_unlock(&srv->paths_mutex);
+
+       return 0;
+
+reject_w_err:
+       return rtrs_rdma_do_reject(cm_id, err);
+
+reject_w_econnreset:
+       return rtrs_rdma_do_reject(cm_id, -ECONNRESET);
+
+close_and_return_err:
+       close_sess(sess);
+       mutex_unlock(&srv->paths_mutex);
+
+       return err;
+}
+
+static int rtrs_srv_rdma_cm_handler(struct rdma_cm_id *cm_id,
+                                    struct rdma_cm_event *ev)
+{
+       struct rtrs_srv_sess *sess = NULL;
+       struct rtrs_sess *s = NULL;
+
+       if (ev->event != RDMA_CM_EVENT_CONNECT_REQUEST) {
+               struct rtrs_con *c = cm_id->context;
+
+               s = c->sess;
+               sess = to_srv_sess(s);
+       }
+
+       switch (ev->event) {
+       case RDMA_CM_EVENT_CONNECT_REQUEST:
+               /*
+                * In case of error cma.c will destroy cm_id,
+                * see cma_process_remove()
+                */
+               return rtrs_rdma_connect(cm_id, ev->param.conn.private_data,
+                                         ev->param.conn.private_data_len);
+       case RDMA_CM_EVENT_ESTABLISHED:
+               /* Nothing here */
+               break;
+       case RDMA_CM_EVENT_REJECTED:
+       case RDMA_CM_EVENT_CONNECT_ERROR:
+       case RDMA_CM_EVENT_UNREACHABLE:
+               rtrs_err(s, "CM error (CM event: %s, err: %d)\n",
+                         rdma_event_msg(ev->event), ev->status);
+               close_sess(sess);
+               break;
+       case RDMA_CM_EVENT_DISCONNECTED:
+       case RDMA_CM_EVENT_ADDR_CHANGE:
+       case RDMA_CM_EVENT_TIMEWAIT_EXIT:
+               close_sess(sess);
+               break;
+       case RDMA_CM_EVENT_DEVICE_REMOVAL:
+               close_sess(sess);
+               break;
+       default:
+               pr_err("Ignoring unexpected CM event %s, err %d\n",
+                      rdma_event_msg(ev->event), ev->status);
+               break;
+       }
+
+       return 0;
+}
+
+static struct rdma_cm_id *rtrs_srv_cm_init(struct rtrs_srv_ctx *ctx,
+                                           struct sockaddr *addr,
+                                           enum rdma_ucm_port_space ps)
+{
+       struct rdma_cm_id *cm_id;
+       int ret;
+
+       cm_id = rdma_create_id(&init_net, rtrs_srv_rdma_cm_handler,
+                              ctx, ps, IB_QPT_RC);
+       if (IS_ERR(cm_id)) {
+               ret = PTR_ERR(cm_id);
+               pr_err("Creating id for RDMA connection failed, err: %d\n",
+                      ret);
+               goto err_out;
+       }
+       ret = rdma_bind_addr(cm_id, addr);
+       if (ret) {
+               pr_err("Binding RDMA address failed, err: %d\n", ret);
+               goto err_cm;
+       }
+       ret = rdma_listen(cm_id, 64);
+       if (ret) {
+               pr_err("Listening on RDMA connection failed, err: %d\n",
+                      ret);
+               goto err_cm;
+       }
+
+       return cm_id;
+
+err_cm:
+       rdma_destroy_id(cm_id);
+err_out:
+
+       return ERR_PTR(ret);
+}
+
+static int rtrs_srv_rdma_init(struct rtrs_srv_ctx *ctx, u16 port)
+{
+       struct sockaddr_in6 sin = {
+               .sin6_family    = AF_INET6,
+               .sin6_addr      = IN6ADDR_ANY_INIT,
+               .sin6_port      = htons(port),
+       };
+       struct sockaddr_ib sib = {
+               .sib_family                     = AF_IB,
+               .sib_sid        = cpu_to_be64(RDMA_IB_IP_PS_IB | port),
+               .sib_sid_mask   = cpu_to_be64(0xffffffffffffffffULL),
+               .sib_pkey       = cpu_to_be16(0xffff),
+       };
+       struct rdma_cm_id *cm_ip, *cm_ib;
+       int ret;
+
+       /*
+        * We accept both IPoIB and IB connections, so we need to keep
+        * two cm id's, one for each socket type and port space.
+        * If the cm initialization of one of the id's fails, we abort
+        * everything.
+        */
+       cm_ip = rtrs_srv_cm_init(ctx, (struct sockaddr *)&sin, RDMA_PS_TCP);
+       if (IS_ERR(cm_ip))
+               return PTR_ERR(cm_ip);
+
+       cm_ib = rtrs_srv_cm_init(ctx, (struct sockaddr *)&sib, RDMA_PS_IB);
+       if (IS_ERR(cm_ib)) {
+               ret = PTR_ERR(cm_ib);
+               goto free_cm_ip;
+       }
+
+       ctx->cm_id_ip = cm_ip;
+       ctx->cm_id_ib = cm_ib;
+
+       return 0;
+
+free_cm_ip:
+       rdma_destroy_id(cm_ip);
+
+       return ret;
+}
+
+static struct rtrs_srv_ctx *alloc_srv_ctx(struct rtrs_srv_ops *ops)
+{
+       struct rtrs_srv_ctx *ctx;
+
+       ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+       if (!ctx)
+               return NULL;
+
+       ctx->ops = *ops;
+       mutex_init(&ctx->srv_mutex);
+       INIT_LIST_HEAD(&ctx->srv_list);
+
+       return ctx;
+}
+
+static void free_srv_ctx(struct rtrs_srv_ctx *ctx)
+{
+       WARN_ON(!list_empty(&ctx->srv_list));
+       mutex_destroy(&ctx->srv_mutex);
+       kfree(ctx);
+}
+
+/**
+ * rtrs_srv_open() - open RTRS server context
+ * @ops:               callback functions
+ * @port:               port to listen on
+ *
+ * Creates server context with specified callbacks.
+ *
+ * Return a valid pointer on success otherwise PTR_ERR.
+ */
+struct rtrs_srv_ctx *rtrs_srv_open(struct rtrs_srv_ops *ops, u16 port)
+{
+       struct rtrs_srv_ctx *ctx;
+       int err;
+
+       ctx = alloc_srv_ctx(ops);
+       if (!ctx)
+               return ERR_PTR(-ENOMEM);
+
+       err = rtrs_srv_rdma_init(ctx, port);
+       if (err) {
+               free_srv_ctx(ctx);
+               return ERR_PTR(err);
+       }
+
+       return ctx;
+}
+EXPORT_SYMBOL(rtrs_srv_open);
+
+static void close_sessions(struct rtrs_srv *srv)
+{
+       struct rtrs_srv_sess *sess;
+
+       mutex_lock(&srv->paths_mutex);
+       list_for_each_entry(sess, &srv->paths_list, s.entry)
+               close_sess(sess);
+       mutex_unlock(&srv->paths_mutex);
+}
+
+static void close_ctx(struct rtrs_srv_ctx *ctx)
+{
+       struct rtrs_srv *srv;
+
+       mutex_lock(&ctx->srv_mutex);
+       list_for_each_entry(srv, &ctx->srv_list, ctx_list)
+               close_sessions(srv);
+       mutex_unlock(&ctx->srv_mutex);
+       flush_workqueue(rtrs_wq);
+}
+
+/**
+ * rtrs_srv_close() - close RTRS server context
+ * @ctx: pointer to server context
+ *
+ * Closes RTRS server context with all client sessions.
+ */
+void rtrs_srv_close(struct rtrs_srv_ctx *ctx)
+{
+       rdma_destroy_id(ctx->cm_id_ip);
+       rdma_destroy_id(ctx->cm_id_ib);
+       close_ctx(ctx);
+       free_srv_ctx(ctx);
+}
+EXPORT_SYMBOL(rtrs_srv_close);
+
+static int check_module_params(void)
+{
+       if (sess_queue_depth < 1 || sess_queue_depth > MAX_SESS_QUEUE_DEPTH) {
+               pr_err("Invalid sess_queue_depth value %d, has to be >= %d, <= %d.\n",
+                      sess_queue_depth, 1, MAX_SESS_QUEUE_DEPTH);
+               return -EINVAL;
+       }
+       if (max_chunk_size < 4096 || !is_power_of_2(max_chunk_size)) {
+               pr_err("Invalid max_chunk_size value %d, has to be >= %d and should be power of two.\n",
+                      max_chunk_size, 4096);
+               return -EINVAL;
+       }
+
+       /*
+        * Check if IB immediate data size is enough to hold the mem_id and the
+        * offset inside the memory chunk
+        */
+       if ((ilog2(sess_queue_depth - 1) + 1) +
+           (ilog2(max_chunk_size - 1) + 1) > MAX_IMM_PAYL_BITS) {
+               pr_err("RDMA immediate size (%db) not enough to encode %d buffers of size %dB. Reduce 'sess_queue_depth' or 'max_chunk_size' parameters.\n",
+                      MAX_IMM_PAYL_BITS, sess_queue_depth, max_chunk_size);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static int __init rtrs_server_init(void)
+{
+       int err;
+
+       pr_info("Loading module %s, proto %s: (max_chunk_size: %d (pure IO %ld, headers %ld) , sess_queue_depth: %d, always_invalidate: %d)\n",
+               KBUILD_MODNAME, RTRS_PROTO_VER_STRING,
+               max_chunk_size, max_chunk_size - MAX_HDR_SIZE, MAX_HDR_SIZE,
+               sess_queue_depth, always_invalidate);
+
+       rtrs_rdma_dev_pd_init(0, &dev_pd);
+
+       err = check_module_params();
+       if (err) {
+               pr_err("Failed to load module, invalid module parameters, err: %d\n",
+                      err);
+               return err;
+       }
+       chunk_pool = mempool_create_page_pool(sess_queue_depth * CHUNK_POOL_SZ,
+                                             get_order(max_chunk_size));
+       if (!chunk_pool)
+               return -ENOMEM;
+       rtrs_dev_class = class_create(THIS_MODULE, "rtrs-server");
+       if (IS_ERR(rtrs_dev_class)) {
+               err = PTR_ERR(rtrs_dev_class);
+               goto out_chunk_pool;
+       }
+       rtrs_wq = alloc_workqueue("rtrs_server_wq", WQ_MEM_RECLAIM, 0);
+       if (!rtrs_wq)
+               goto out_dev_class;
+
+       return 0;
+
+out_dev_class:
+       class_destroy(rtrs_dev_class);
+out_chunk_pool:
+       mempool_destroy(chunk_pool);
+
+       return err;
+}
+
+static void __exit rtrs_server_exit(void)
+{
+       destroy_workqueue(rtrs_wq);
+       class_destroy(rtrs_dev_class);
+       mempool_destroy(chunk_pool);
+       rtrs_rdma_dev_pd_deinit(&dev_pd);
+}
+
+module_init(rtrs_server_init);
+module_exit(rtrs_server_exit);