text: /*
   * NVMe over Fabrics RDMA target.
   * Copyright (c) 2015-2016 HGST, a Western Digital Company.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   */
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  #include <linux/atomic.h>
  #include <linux/ctype.h>
  #include <linux/delay.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/nvme.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/wait.h>
  #include <linux/inet.h>
  #include <asm/unaligned.h>
  
  #include <rdma/ib_verbs.h>
  #include <rdma/rdma_cm.h>
  #include <rdma/rw.h>
  
  #include <linux/nvme-rdma.h>
  #include "nvmet.h"
  
  /*
   * We allow up to a page of inline data to go with the SQE
   */
  #define NVMET_RDMA_INLINE_DATA_SIZE	PAGE_SIZE
  
  struct nvmet_rdma_cmd {
  	struct ib_sge		sge[2];
  	struct ib_cqe		cqe;
  	struct ib_recv_wr	wr;
  	struct scatterlist	inline_sg;
  	struct page		*inline_page;
  	struct nvme_command     *nvme_cmd;
  	struct nvmet_rdma_queue	*queue;
  };
  
  enum {
  	NVMET_RDMA_REQ_INLINE_DATA	= (1 << 0),
  	NVMET_RDMA_REQ_INVALIDATE_RKEY	= (1 << 1),
  };
  
  struct nvmet_rdma_rsp {
  	struct ib_sge		send_sge;
  	struct ib_cqe		send_cqe;
  	struct ib_send_wr	send_wr;
  
  	struct nvmet_rdma_cmd	*cmd;
  	struct nvmet_rdma_queue	*queue;
  
  	struct ib_cqe		read_cqe;
  	struct rdma_rw_ctx	rw;
  
  	struct nvmet_req	req;
  
  	bool			allocated;
  	u8			n_rdma;
  	u32			flags;
  	u32			invalidate_rkey;
  
  	struct list_head	wait_list;
  	struct list_head	free_list;
  };
  
  enum nvmet_rdma_queue_state {
  	NVMET_RDMA_Q_CONNECTING,
  	NVMET_RDMA_Q_LIVE,
  	NVMET_RDMA_Q_DISCONNECTING,
  	NVMET_RDMA_IN_DEVICE_REMOVAL,
  };
  
  struct nvmet_rdma_queue {
  	struct rdma_cm_id	*cm_id;
  	struct nvmet_port	*port;
  	struct ib_cq		*cq;
  	atomic_t		sq_wr_avail;
  	struct nvmet_rdma_device *dev;
  	spinlock_t		state_lock;
  	enum nvmet_rdma_queue_state state;
  	struct nvmet_cq		nvme_cq;
  	struct nvmet_sq		nvme_sq;
  
  	struct nvmet_rdma_rsp	*rsps;
  	struct list_head	free_rsps;
  	spinlock_t		rsps_lock;
  	struct nvmet_rdma_cmd	*cmds;
  
  	struct work_struct	release_work;
  	struct list_head	rsp_wait_list;
  	struct list_head	rsp_wr_wait_list;
  	spinlock_t		rsp_wr_wait_lock;
  
  	int			idx;
  	int			host_qid;
  	int			recv_queue_size;
  	int			send_queue_size;
  
  	struct list_head	queue_list;
  };
  
  struct nvmet_rdma_device {
  	struct ib_device	*device;
  	struct ib_pd		*pd;
  	struct ib_srq		*srq;
  	struct nvmet_rdma_cmd	*srq_cmds;
  	size_t			srq_size;
  	struct kref		ref;
  	struct list_head	entry;
  };
  
  static bool nvmet_rdma_use_srq;
  module_param_named(use_srq, nvmet_rdma_use_srq, bool, 0444);
  MODULE_PARM_DESC(use_srq, "Use shared receive queue.");
  
  static DEFINE_IDA(nvmet_rdma_queue_ida);
  static LIST_HEAD(nvmet_rdma_queue_list);
  static DEFINE_MUTEX(nvmet_rdma_queue_mutex);
  
  static LIST_HEAD(device_list);
  static DEFINE_MUTEX(device_list_mutex);
  
  static bool nvmet_rdma_execute_command(struct nvmet_rdma_rsp *rsp);
  static void nvmet_rdma_send_done(struct ib_cq *cq, struct ib_wc *wc);
  static void nvmet_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc);
  static void nvmet_rdma_read_data_done(struct ib_cq *cq, struct ib_wc *wc);
  static void nvmet_rdma_qp_event(struct ib_event *event, void *priv);
  static void nvmet_rdma_queue_disconnect(struct nvmet_rdma_queue *queue);
  static void nvmet_rdma_free_rsp(struct nvmet_rdma_device *ndev,
  				struct nvmet_rdma_rsp *r);
  static int nvmet_rdma_alloc_rsp(struct nvmet_rdma_device *ndev,
  				struct nvmet_rdma_rsp *r);
  
  static struct nvmet_fabrics_ops nvmet_rdma_ops;
  
  /* XXX: really should move to a generic header sooner or later.. */
  static inline u32 get_unaligned_le24(const u8 *p)
  {
  	return (u32)p[0] | (u32)p[1] << 8 | (u32)p[2] << 16;
  }
  
  static inline bool nvmet_rdma_need_data_in(struct nvmet_rdma_rsp *rsp)
  {
  	return nvme_is_write(rsp->req.cmd) &&
  		rsp->req.data_len &&
  		!(rsp->flags & NVMET_RDMA_REQ_INLINE_DATA);
  }
  
  static inline bool nvmet_rdma_need_data_out(struct nvmet_rdma_rsp *rsp)
  {
  	return !nvme_is_write(rsp->req.cmd) &&
  		rsp->req.data_len &&
  		!rsp->req.rsp->status &&
  		!(rsp->flags & NVMET_RDMA_REQ_INLINE_DATA);
  }
  
  static inline struct nvmet_rdma_rsp *
  nvmet_rdma_get_rsp(struct nvmet_rdma_queue *queue)
  {
  	struct nvmet_rdma_rsp *rsp;
  	unsigned long flags;
  
  	spin_lock_irqsave(&queue->rsps_lock, flags);
  	rsp = list_first_entry_or_null(&queue->free_rsps,
  				struct nvmet_rdma_rsp, free_list);
  	if (likely(rsp))
  		list_del(&rsp->free_list);
  	spin_unlock_irqrestore(&queue->rsps_lock, flags);
  
  	if (unlikely(!rsp)) {
  		int ret;
  
  		rsp = kzalloc(sizeof(*rsp), GFP_KERNEL);
  		if (unlikely(!rsp))
  			return NULL;
  		ret = nvmet_rdma_alloc_rsp(queue->dev, rsp);
  		if (unlikely(ret)) {
  			kfree(rsp);
  			return NULL;
  		}
  
  		rsp->allocated = true;
  	}
  
  	return rsp;
  }
  
  static inline void
  nvmet_rdma_put_rsp(struct nvmet_rdma_rsp *rsp)
  {
  	unsigned long flags;
  
  	if (unlikely(rsp->allocated)) {
  		nvmet_rdma_free_rsp(rsp->queue->dev, rsp);
  		kfree(rsp);
  		return;
  	}
  
  	spin_lock_irqsave(&rsp->queue->rsps_lock, flags);
  	list_add_tail(&rsp->free_list, &rsp->queue->free_rsps);
  	spin_unlock_irqrestore(&rsp->queue->rsps_lock, flags);
  }
  
  static void nvmet_rdma_free_sgl(struct scatterlist *sgl, unsigned int nents)
  {
  	struct scatterlist *sg;
  	int count;
  
  	if (!sgl || !nents)
  		return;
  
  	for_each_sg(sgl, sg, nents, count)
  		__free_page(sg_page(sg));
  	kfree(sgl);
  }
  
  static int nvmet_rdma_alloc_sgl(struct scatterlist **sgl, unsigned int *nents,
  		u32 length)
  {
  	struct scatterlist *sg;
  	struct page *page;
  	unsigned int nent;
  	int i = 0;
  
  	nent = DIV_ROUND_UP(length, PAGE_SIZE);
  	sg = kmalloc_array(nent, sizeof(struct scatterlist), GFP_KERNEL);
  	if (!sg)
  		goto out;
  
  	sg_init_table(sg, nent);
  
  	while (length) {
  		u32 page_len = min_t(u32, length, PAGE_SIZE);
  
  		page = alloc_page(GFP_KERNEL);
  		if (!page)
  			goto out_free_pages;
  
  		sg_set_page(&sg[i], page, page_len, 0);
  		length -= page_len;
  		i++;
  	}
  	*sgl = sg;
  	*nents = nent;
  	return 0;
  
  out_free_pages:
  	while (i > 0) {
  		i--;
  		__free_page(sg_page(&sg[i]));
  	}
  	kfree(sg);
  out:
  	return NVME_SC_INTERNAL;
  }
  
  static int nvmet_rdma_alloc_cmd(struct nvmet_rdma_device *ndev,
  			struct nvmet_rdma_cmd *c, bool admin)
  {
  	/* NVMe command / RDMA RECV */
  	c->nvme_cmd = kmalloc(sizeof(*c->nvme_cmd), GFP_KERNEL);
  	if (!c->nvme_cmd)
  		goto out;
  
  	c->sge[0].addr = ib_dma_map_single(ndev->device, c->nvme_cmd,
  			sizeof(*c->nvme_cmd), DMA_FROM_DEVICE);
  	if (ib_dma_mapping_error(ndev->device, c->sge[0].addr))
  		goto out_free_cmd;
  
  	c->sge[0].length = sizeof(*c->nvme_cmd);
  	c->sge[0].lkey = ndev->pd->local_dma_lkey;
  
  	if (!admin) {
  		c->inline_page = alloc_pages(GFP_KERNEL,
  				get_order(NVMET_RDMA_INLINE_DATA_SIZE));
  		if (!c->inline_page)
  			goto out_unmap_cmd;
  		c->sge[1].addr = ib_dma_map_page(ndev->device,
  				c->inline_page, 0, NVMET_RDMA_INLINE_DATA_SIZE,
  				DMA_FROM_DEVICE);
  		if (ib_dma_mapping_error(ndev->device, c->sge[1].addr))
  			goto out_free_inline_page;
  		c->sge[1].length = NVMET_RDMA_INLINE_DATA_SIZE;
  		c->sge[1].lkey = ndev->pd->local_dma_lkey;
  	}
  
  	c->cqe.done = nvmet_rdma_recv_done;
  
  	c->wr.wr_cqe = &c->cqe;
  	c->wr.sg_list = c->sge;
  	c->wr.num_sge = admin ? 1 : 2;
  
  	return 0;
  
  out_free_inline_page:
  	if (!admin) {
  		__free_pages(c->inline_page,
  				get_order(NVMET_RDMA_INLINE_DATA_SIZE));
  	}
  out_unmap_cmd:
  	ib_dma_unmap_single(ndev->device, c->sge[0].addr,
  			sizeof(*c->nvme_cmd), DMA_FROM_DEVICE);
  out_free_cmd:
  	kfree(c->nvme_cmd);
  
  out:
  	return -ENOMEM;
  }
  
  static void nvmet_rdma_free_cmd(struct nvmet_rdma_device *ndev,
  		struct nvmet_rdma_cmd *c, bool admin)
  {
  	if (!admin) {
  		ib_dma_unmap_page(ndev->device, c->sge[1].addr,
  				NVMET_RDMA_INLINE_DATA_SIZE, DMA_FROM_DEVICE);
  		__free_pages(c->inline_page,
  				get_order(NVMET_RDMA_INLINE_DATA_SIZE));
  	}
  	ib_dma_unmap_single(ndev->device, c->sge[0].addr,
  				sizeof(*c->nvme_cmd), DMA_FROM_DEVICE);
  	kfree(c->nvme_cmd);
  }
  
  static struct nvmet_rdma_cmd *
  nvmet_rdma_alloc_cmds(struct nvmet_rdma_device *ndev,
  		int nr_cmds, bool admin)
  {
  	struct nvmet_rdma_cmd *cmds;
  	int ret = -EINVAL, i;
  
  	cmds = kcalloc(nr_cmds, sizeof(struct nvmet_rdma_cmd), GFP_KERNEL);
  	if (!cmds)
  		goto out;
  
  	for (i = 0; i < nr_cmds; i++) {
  		ret = nvmet_rdma_alloc_cmd(ndev, cmds + i, admin);
  		if (ret)
  			goto out_free;
  	}
  
  	return cmds;
  
  out_free:
  	while (--i >= 0)
  		nvmet_rdma_free_cmd(ndev, cmds + i, admin);
  	kfree(cmds);
  out:
  	return ERR_PTR(ret);
  }
  
  static void nvmet_rdma_free_cmds(struct nvmet_rdma_device *ndev,
  		struct nvmet_rdma_cmd *cmds, int nr_cmds, bool admin)
  {
  	int i;
  
  	for (i = 0; i < nr_cmds; i++)
  		nvmet_rdma_free_cmd(ndev, cmds + i, admin);
  	kfree(cmds);
  }
  
  static int nvmet_rdma_alloc_rsp(struct nvmet_rdma_device *ndev,
  		struct nvmet_rdma_rsp *r)
  {
  	/* NVMe CQE / RDMA SEND */
  	r->req.rsp = kmalloc(sizeof(*r->req.rsp), GFP_KERNEL);
  	if (!r->req.rsp)
  		goto out;
  
  	r->send_sge.addr = ib_dma_map_single(ndev->device, r->req.rsp,
  			sizeof(*r->req.rsp), DMA_TO_DEVICE);
  	if (ib_dma_mapping_error(ndev->device, r->send_sge.addr))
  		goto out_free_rsp;
  
  	r->send_sge.length = sizeof(*r->req.rsp);
  	r->send_sge.lkey = ndev->pd->local_dma_lkey;
  
  	r->send_cqe.done = nvmet_rdma_send_done;
  
  	r->send_wr.wr_cqe = &r->send_cqe;
  	r->send_wr.sg_list = &r->send_sge;
  	r->send_wr.num_sge = 1;
  	r->send_wr.send_flags = IB_SEND_SIGNALED;
  
  	/* Data In / RDMA READ */
  	r->read_cqe.done = nvmet_rdma_read_data_done;
  	return 0;
  
  out_free_rsp:
  	kfree(r->req.rsp);
  out:
  	return -ENOMEM;
  }
  
  static void nvmet_rdma_free_rsp(struct nvmet_rdma_device *ndev,
  		struct nvmet_rdma_rsp *r)
  {
  	ib_dma_unmap_single(ndev->device, r->send_sge.addr,
  				sizeof(*r->req.rsp), DMA_TO_DEVICE);
  	kfree(r->req.rsp);
  }
  
  static int
  nvmet_rdma_alloc_rsps(struct nvmet_rdma_queue *queue)
  {
  	struct nvmet_rdma_device *ndev = queue->dev;
  	int nr_rsps = queue->recv_queue_size * 2;
  	int ret = -EINVAL, i;
  
  	queue->rsps = kcalloc(nr_rsps, sizeof(struct nvmet_rdma_rsp),
  			GFP_KERNEL);
  	if (!queue->rsps)
  		goto out;
  
  	for (i = 0; i < nr_rsps; i++) {
  		struct nvmet_rdma_rsp *rsp = &queue->rsps[i];
  
  		ret = nvmet_rdma_alloc_rsp(ndev, rsp);
  		if (ret)
  			goto out_free;
  
  		list_add_tail(&rsp->free_list, &queue->free_rsps);
  	}
  
  	return 0;
  
  out_free:
  	while (--i >= 0) {
  		struct nvmet_rdma_rsp *rsp = &queue->rsps[i];
  
  		list_del(&rsp->free_list);
  		nvmet_rdma_free_rsp(ndev, rsp);
  	}
  	kfree(queue->rsps);
  out:
  	return ret;
  }
  
  static void nvmet_rdma_free_rsps(struct nvmet_rdma_queue *queue)
  {
  	struct nvmet_rdma_device *ndev = queue->dev;
  	int i, nr_rsps = queue->recv_queue_size * 2;
  
  	for (i = 0; i < nr_rsps; i++) {
  		struct nvmet_rdma_rsp *rsp = &queue->rsps[i];
  
  		list_del(&rsp->free_list);
  		nvmet_rdma_free_rsp(ndev, rsp);
  	}
  	kfree(queue->rsps);
  }
  
  static int nvmet_rdma_post_recv(struct nvmet_rdma_device *ndev,
  		struct nvmet_rdma_cmd *cmd)
  {
  	struct ib_recv_wr *bad_wr;
  
  	ib_dma_sync_single_for_device(ndev->device,
  		cmd->sge[0].addr, cmd->sge[0].length,
  		DMA_FROM_DEVICE);
  
  	if (ndev->srq)
  		return ib_post_srq_recv(ndev->srq, &cmd->wr, &bad_wr);
  	return ib_post_recv(cmd->queue->cm_id->qp, &cmd->wr, &bad_wr);
  }
  
  static void nvmet_rdma_process_wr_wait_list(struct nvmet_rdma_queue *queue)
  {
  	spin_lock(&queue->rsp_wr_wait_lock);
  	while (!list_empty(&queue->rsp_wr_wait_list)) {
  		struct nvmet_rdma_rsp *rsp;
  		bool ret;
  
  		rsp = list_entry(queue->rsp_wr_wait_list.next,
  				struct nvmet_rdma_rsp, wait_list);
  		list_del(&rsp->wait_list);
  
  		spin_unlock(&queue->rsp_wr_wait_lock);
  		ret = nvmet_rdma_execute_command(rsp);
  		spin_lock(&queue->rsp_wr_wait_lock);
  
  		if (!ret) {
  			list_add(&rsp->wait_list, &queue->rsp_wr_wait_list);
  			break;
  		}
  	}
  	spin_unlock(&queue->rsp_wr_wait_lock);
  }
  
  
  static void nvmet_rdma_release_rsp(struct nvmet_rdma_rsp *rsp)
  {
  	struct nvmet_rdma_queue *queue = rsp->queue;
  
  	atomic_add(1 + rsp->n_rdma, &queue->sq_wr_avail);
  
  	if (rsp->n_rdma) {
  		rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
  				queue->cm_id->port_num, rsp->req.sg,
  				rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
  	}
  
  	if (rsp->req.sg != &rsp->cmd->inline_sg)
  		nvmet_rdma_free_sgl(rsp->req.sg, rsp->req.sg_cnt);
  
  	if (unlikely(!list_empty_careful(&queue->rsp_wr_wait_list)))
  		nvmet_rdma_process_wr_wait_list(queue);
  
  	nvmet_rdma_put_rsp(rsp);
  }
  
  static void nvmet_rdma_error_comp(struct nvmet_rdma_queue *queue)
  {
  	if (queue->nvme_sq.ctrl) {
  		nvmet_ctrl_fatal_error(queue->nvme_sq.ctrl);
  	} else {
  		/*
  		 * we didn't setup the controller yet in case
  		 * of admin connect error, just disconnect and
  		 * cleanup the queue
  		 */
  		nvmet_rdma_queue_disconnect(queue);
  	}
  }
  
  static void nvmet_rdma_send_done(struct ib_cq *cq, struct ib_wc *wc)
  {
  	struct nvmet_rdma_rsp *rsp =
  		container_of(wc->wr_cqe, struct nvmet_rdma_rsp, send_cqe);
  	struct nvmet_rdma_queue *queue = cq->cq_context;
  
  	nvmet_rdma_release_rsp(rsp);
  
  	if (unlikely(wc->status != IB_WC_SUCCESS &&
  		     wc->status != IB_WC_WR_FLUSH_ERR)) {
  		pr_err("SEND for CQE 0x%p failed with status %s (%d).\n",
  			wc->wr_cqe, ib_wc_status_msg(wc->status), wc->status);
  		nvmet_rdma_error_comp(queue);
  	}
  }
  
  static void nvmet_rdma_queue_response(struct nvmet_req *req)
  {
  	struct nvmet_rdma_rsp *rsp =
  		container_of(req, struct nvmet_rdma_rsp, req);
  	struct rdma_cm_id *cm_id = rsp->queue->cm_id;
  	struct ib_send_wr *first_wr, *bad_wr;
  
  	if (rsp->flags & NVMET_RDMA_REQ_INVALIDATE_RKEY) {
  		rsp->send_wr.opcode = IB_WR_SEND_WITH_INV;
  		rsp->send_wr.ex.invalidate_rkey = rsp->invalidate_rkey;
  	} else {
  		rsp->send_wr.opcode = IB_WR_SEND;
  	}
  
  	if (nvmet_rdma_need_data_out(rsp))
  		first_wr = rdma_rw_ctx_wrs(&rsp->rw, cm_id->qp,
  				cm_id->port_num, NULL, &rsp->send_wr);
  	else
  		first_wr = &rsp->send_wr;
  
  	nvmet_rdma_post_recv(rsp->queue->dev, rsp->cmd);
  
  	ib_dma_sync_single_for_device(rsp->queue->dev->device,
  		rsp->send_sge.addr, rsp->send_sge.length,
  		DMA_TO_DEVICE);
  
  	if (ib_post_send(cm_id->qp, first_wr, &bad_wr)) {
  		pr_err("sending cmd response failed\n");
  		nvmet_rdma_release_rsp(rsp);
  	}
  }
  
  static void nvmet_rdma_read_data_done(struct ib_cq *cq, struct ib_wc *wc)
  {
  	struct nvmet_rdma_rsp *rsp =
  		container_of(wc->wr_cqe, struct nvmet_rdma_rsp, read_cqe);
  	struct nvmet_rdma_queue *queue = cq->cq_context;
  
  	WARN_ON(rsp->n_rdma <= 0);
  	atomic_add(rsp->n_rdma, &queue->sq_wr_avail);
  	rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
  			queue->cm_id->port_num, rsp->req.sg,
  			rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
  	rsp->n_rdma = 0;
  
  	if (unlikely(wc->status != IB_WC_SUCCESS)) {
  		nvmet_rdma_release_rsp(rsp);
  		if (wc->status != IB_WC_WR_FLUSH_ERR) {
  			pr_info("RDMA READ for CQE 0x%p failed with status %s (%d).\n",
  				wc->wr_cqe, ib_wc_status_msg(wc->status), wc->status);
  			nvmet_rdma_error_comp(queue);
  		}
  		return;
  	}
  
  	rsp->req.execute(&rsp->req);
  }
  
  static void nvmet_rdma_use_inline_sg(struct nvmet_rdma_rsp *rsp, u32 len,
  		u64 off)
  {
  	sg_init_table(&rsp->cmd->inline_sg, 1);
  	sg_set_page(&rsp->cmd->inline_sg, rsp->cmd->inline_page, len, off);
  	rsp->req.sg = &rsp->cmd->inline_sg;
  	rsp->req.sg_cnt = 1;
  }
  
  static u16 nvmet_rdma_map_sgl_inline(struct nvmet_rdma_rsp *rsp)
  {
  	struct nvme_sgl_desc *sgl = &rsp->req.cmd->common.dptr.sgl;
  	u64 off = le64_to_cpu(sgl->addr);
  	u32 len = le32_to_cpu(sgl->length);
  
  	if (!nvme_is_write(rsp->req.cmd))
  		return NVME_SC_INVALID_FIELD | NVME_SC_DNR;
  
  	if (off + len > NVMET_RDMA_INLINE_DATA_SIZE) {
  		pr_err("invalid inline data offset!\n");
  		return NVME_SC_SGL_INVALID_OFFSET | NVME_SC_DNR;
  	}
  
  	/* no data command? */
  	if (!len)
  		return 0;
  
  	nvmet_rdma_use_inline_sg(rsp, len, off);
  	rsp->flags |= NVMET_RDMA_REQ_INLINE_DATA;
  	return 0;
  }
  
  static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
  		struct nvme_keyed_sgl_desc *sgl, bool invalidate)
  {
  	struct rdma_cm_id *cm_id = rsp->queue->cm_id;
  	u64 addr = le64_to_cpu(sgl->addr);
  	u32 len = get_unaligned_le24(sgl->length);
  	u32 key = get_unaligned_le32(sgl->key);
  	int ret;
  	u16 status;
  
  	/* no data command? */
  	if (!len)
  		return 0;
  
  	status = nvmet_rdma_alloc_sgl(&rsp->req.sg, &rsp->req.sg_cnt,
  			len);
  	if (status)
  		return status;
  
  	ret = rdma_rw_ctx_init(&rsp->rw, cm_id->qp, cm_id->port_num,
  			rsp->req.sg, rsp->req.sg_cnt, 0, addr, key,
  			nvmet_data_dir(&rsp->req));
  	if (ret < 0)
  		return NVME_SC_INTERNAL;
  	rsp->n_rdma += ret;
  
  	if (invalidate) {
  		rsp->invalidate_rkey = key;
  		rsp->flags |= NVMET_RDMA_REQ_INVALIDATE_RKEY;
  	}
  
  	return 0;
  }
  
  static u16 nvmet_rdma_map_sgl(struct nvmet_rdma_rsp *rsp)
  {
  	struct nvme_keyed_sgl_desc *sgl = &rsp->req.cmd->common.dptr.ksgl;
  
  	switch (sgl->type >> 4) {
  	case NVME_SGL_FMT_DATA_DESC:
  		switch (sgl->type & 0xf) {
  		case NVME_SGL_FMT_OFFSET:
  			return nvmet_rdma_map_sgl_inline(rsp);
  		default:
  			pr_err("invalid SGL subtype: %#x\n", sgl->type);
  			return NVME_SC_INVALID_FIELD | NVME_SC_DNR;
  		}
  	case NVME_KEY_SGL_FMT_DATA_DESC:
  		switch (sgl->type & 0xf) {
  		case NVME_SGL_FMT_ADDRESS | NVME_SGL_FMT_INVALIDATE:
  			return nvmet_rdma_map_sgl_keyed(rsp, sgl, true);
  		case NVME_SGL_FMT_ADDRESS:
  			return nvmet_rdma_map_sgl_keyed(rsp, sgl, false);
  		default:
  			pr_err("invalid SGL subtype: %#x\n", sgl->type);
  			return NVME_SC_INVALID_FIELD | NVME_SC_DNR;
  		}
  	default:
  		pr_err("invalid SGL type: %#x\n", sgl->type);
  		return NVME_SC_SGL_INVALID_TYPE | NVME_SC_DNR;
  	}
  }
  
  static bool nvmet_rdma_execute_command(struct nvmet_rdma_rsp *rsp)
  {
  	struct nvmet_rdma_queue *queue = rsp->queue;
  
  	if (unlikely(atomic_sub_return(1 + rsp->n_rdma,
  			&queue->sq_wr_avail) < 0)) {
  		pr_debug("IB send queue full (needed %d): queue %u cntlid %u\n",
  				1 + rsp->n_rdma, queue->idx,
  				queue->nvme_sq.ctrl->cntlid);
  		atomic_add(1 + rsp->n_rdma, &queue->sq_wr_avail);
  		return false;
  	}
  
  	if (nvmet_rdma_need_data_in(rsp)) {
  		if (rdma_rw_ctx_post(&rsp->rw, queue->cm_id->qp,
  				queue->cm_id->port_num, &rsp->read_cqe, NULL))
  			nvmet_req_complete(&rsp->req, NVME_SC_DATA_XFER_ERROR);
  	} else {
  		rsp->req.execute(&rsp->req);
  	}
  
  	return true;
  }
  
  static void nvmet_rdma_handle_command(struct nvmet_rdma_queue *queue,
  		struct nvmet_rdma_rsp *cmd)
  {
  	u16 status;
  
  	ib_dma_sync_single_for_cpu(queue->dev->device,
  		cmd->cmd->sge[0].addr, cmd->cmd->sge[0].length,
  		DMA_FROM_DEVICE);
  	ib_dma_sync_single_for_cpu(queue->dev->device,
  		cmd->send_sge.addr, cmd->send_sge.length,
  		DMA_TO_DEVICE);
  
  	if (!nvmet_req_init(&cmd->req, &queue->nvme_cq,
  			&queue->nvme_sq, &nvmet_rdma_ops))
  		return;
  
  	status = nvmet_rdma_map_sgl(cmd);
  	if (status)
  		goto out_err;
  
  	if (unlikely(!nvmet_rdma_execute_command(cmd))) {
  		spin_lock(&queue->rsp_wr_wait_lock);
  		list_add_tail(&cmd->wait_list, &queue->rsp_wr_wait_list);
  		spin_unlock(&queue->rsp_wr_wait_lock);
  	}
  
  	return;
  
  out_err:
  	nvmet_req_complete(&cmd->req, status);
  }
  
  static void nvmet_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
  {
  	struct nvmet_rdma_cmd *cmd =
  		container_of(wc->wr_cqe, struct nvmet_rdma_cmd, cqe);
  	struct nvmet_rdma_queue *queue = cq->cq_context;
  	struct nvmet_rdma_rsp *rsp;
  
  	if (unlikely(wc->status != IB_WC_SUCCESS)) {
  		if (wc->status != IB_WC_WR_FLUSH_ERR) {
  			pr_err("RECV for CQE 0x%p failed with status %s (%d)\n",
  				wc->wr_cqe, ib_wc_status_msg(wc->status),
  				wc->status);
  			nvmet_rdma_error_comp(queue);
  		}
  		return;
  	}
  
  	if (unlikely(wc->byte_len < sizeof(struct nvme_command))) {
  		pr_err("Ctrl Fatal Error: capsule size less than 64 bytes\n");
  		nvmet_rdma_error_comp(queue);
  		return;
  	}
  
  	cmd->queue = queue;
  	rsp = nvmet_rdma_get_rsp(queue);
  	if (unlikely(!rsp)) {
  		/*
  		 * we get here only under memory pressure,
  		 * silently drop and have the host retry
  		 * as we can't even fail it.
  		 */
  		nvmet_rdma_post_recv(queue->dev, cmd);
  		return;
  	}
  	rsp->queue = queue;
  	rsp->cmd = cmd;
  	rsp->flags = 0;
  	rsp->req.cmd = cmd->nvme_cmd;
  	rsp->req.port = queue->port;
  	rsp->n_rdma = 0;
  
  	if (unlikely(queue->state != NVMET_RDMA_Q_LIVE)) {
  		unsigned long flags;
  
  		spin_lock_irqsave(&queue->state_lock, flags);
  		if (queue->state == NVMET_RDMA_Q_CONNECTING)
  			list_add_tail(&rsp->wait_list, &queue->rsp_wait_list);
  		else
  			nvmet_rdma_put_rsp(rsp);
  		spin_unlock_irqrestore(&queue->state_lock, flags);
  		return;
  	}
  
  	nvmet_rdma_handle_command(queue, rsp);
  }
  
  static void nvmet_rdma_destroy_srq(struct nvmet_rdma_device *ndev)
  {
  	if (!ndev->srq)
  		return;
  
  	nvmet_rdma_free_cmds(ndev, ndev->srq_cmds, ndev->srq_size, false);
  	ib_destroy_srq(ndev->srq);
  }
  
  static int nvmet_rdma_init_srq(struct nvmet_rdma_device *ndev)
  {
  	struct ib_srq_init_attr srq_attr = { NULL, };
  	struct ib_srq *srq;
  	size_t srq_size;
  	int ret, i;
  
  	srq_size = 4095;	/* XXX: tune */
  
  	srq_attr.attr.max_wr = srq_size;
  	srq_attr.attr.max_sge = 2;
  	srq_attr.attr.srq_limit = 0;
  	srq_attr.srq_type = IB_SRQT_BASIC;
  	srq = ib_create_srq(ndev->pd, &srq_attr);
  	if (IS_ERR(srq)) {
  		/*
  		 * If SRQs aren't supported we just go ahead and use normal
  		 * non-shared receive queues.
  		 */
  		pr_info("SRQ requested but not supported.\n");
  		return 0;
  	}
  
  	ndev->srq_cmds = nvmet_rdma_alloc_cmds(ndev, srq_size, false);
  	if (IS_ERR(ndev->srq_cmds)) {
  		ret = PTR_ERR(ndev->srq_cmds);
  		goto out_destroy_srq;
  	}
  
  	ndev->srq = srq;
  	ndev->srq_size = srq_size;
  
  	for (i = 0; i < srq_size; i++)
  		nvmet_rdma_post_recv(ndev, &ndev->srq_cmds[i]);
  
  	return 0;
  
  out_destroy_srq:
  	ib_destroy_srq(srq);
  	return ret;
  }
  
  static void nvmet_rdma_free_dev(struct kref *ref)
  {
  	struct nvmet_rdma_device *ndev =
  		container_of(ref, struct nvmet_rdma_device, ref);
  
  	mutex_lock(&device_list_mutex);
  	list_del(&ndev->entry);
  	mutex_unlock(&device_list_mutex);
  
  	nvmet_rdma_destroy_srq(ndev);
  	ib_dealloc_pd(ndev->pd);
  
  	kfree(ndev);
  }
  
  static struct nvmet_rdma_device *
  nvmet_rdma_find_get_device(struct rdma_cm_id *cm_id)
  {
  	struct nvmet_rdma_device *ndev;
  	int ret;
  
  	mutex_lock(&device_list_mutex);
  	list_for_each_entry(ndev, &device_list, entry) {
  		if (ndev->device->node_guid == cm_id->device->node_guid &&
  		    kref_get_unless_zero(&ndev->ref))
  			goto out_unlock;
  	}
  
  	ndev = kzalloc(sizeof(*ndev), GFP_KERNEL);
  	if (!ndev)
  		goto out_err;
  
  	ndev->device = cm_id->device;
  	kref_init(&ndev->ref);
  
  	ndev->pd = ib_alloc_pd(ndev->device, 0);
  	if (IS_ERR(ndev->pd))
  		goto out_free_dev;
  
  	if (nvmet_rdma_use_srq) {
  		ret = nvmet_rdma_init_srq(ndev);
  		if (ret)
  			goto out_free_pd;
  	}
  
  	list_add(&ndev->entry, &device_list);
  out_unlock:
  	mutex_unlock(&device_list_mutex);
  	pr_debug("added %s.\n", ndev->device->name);
  	return ndev;
  
  out_free_pd:
  	ib_dealloc_pd(ndev->pd);
  out_free_dev:
  	kfree(ndev);
  out_err:
  	mutex_unlock(&device_list_mutex);
  	return NULL;
  }
  
  static int nvmet_rdma_create_queue_ib(struct nvmet_rdma_queue *queue)
  {
  	struct ib_qp_init_attr qp_attr;
  	struct nvmet_rdma_device *ndev = queue->dev;
  	int comp_vector, nr_cqe, ret, i;
  
  	/*
  	 * Spread the io queues across completion vectors,
  	 * but still keep all admin queues on vector 0.
  	 */
  	comp_vector = !queue->host_qid ? 0 :
  		queue->idx % ndev->device->num_comp_vectors;
  
  	/*
  	 * Reserve CQ slots for RECV + RDMA_READ/RDMA_WRITE + RDMA_SEND.
  	 */
  	nr_cqe = queue->recv_queue_size + 2 * queue->send_queue_size;
  
  	queue->cq = ib_alloc_cq(ndev->device, queue,
  			nr_cqe + 1, comp_vector,
  			IB_POLL_WORKQUEUE);
  	if (IS_ERR(queue->cq)) {
  		ret = PTR_ERR(queue->cq);
  		pr_err("failed to create CQ cqe= %d ret= %d\n",
  		       nr_cqe + 1, ret);
  		goto out;
  	}
  
  	memset(&qp_attr, 0, sizeof(qp_attr));
  	qp_attr.qp_context = queue;
  	qp_attr.event_handler = nvmet_rdma_qp_event;
  	qp_attr.send_cq = queue->cq;
  	qp_attr.recv_cq = queue->cq;
  	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
  	qp_attr.qp_type = IB_QPT_RC;
  	/* +1 for drain */
  	qp_attr.cap.max_send_wr = queue->send_queue_size + 1;
  	qp_attr.cap.max_rdma_ctxs = queue->send_queue_size;
  	qp_attr.cap.max_send_sge = max(ndev->device->attrs.max_sge_rd,
  					ndev->device->attrs.max_sge);
  
  	if (ndev->srq) {
  		qp_attr.srq = ndev->srq;
  	} else {
  		/* +1 for drain */
  		qp_attr.cap.max_recv_wr = 1 + queue->recv_queue_size;
  		qp_attr.cap.max_recv_sge = 2;
  	}
  
  	ret = rdma_create_qp(queue->cm_id, ndev->pd, &qp_attr);
  	if (ret) {
  		pr_err("failed to create_qp ret= %d\n", ret);
  		goto err_destroy_cq;
  	}
  
  	atomic_set(&queue->sq_wr_avail, qp_attr.cap.max_send_wr);
  
  	pr_debug("%s: max_cqe= %d max_sge= %d sq_size = %d cm_id= %p\n",
  		 __func__, queue->cq->cqe, qp_attr.cap.max_send_sge,
  		 qp_attr.cap.max_send_wr, queue->cm_id);
  
  	if (!ndev->srq) {
  		for (i = 0; i < queue->recv_queue_size; i++) {
  			queue->cmds[i].queue = queue;
  			nvmet_rdma_post_recv(ndev, &queue->cmds[i]);
  		}
  	}
  
  out:
  	return ret;
  
  err_destroy_cq:
  	ib_free_cq(queue->cq);
  	goto out;
  }
  
  static void nvmet_rdma_destroy_queue_ib(struct nvmet_rdma_queue *queue)
  {
  	ib_drain_qp(queue->cm_id->qp);
  	rdma_destroy_qp(queue->cm_id);
  	ib_free_cq(queue->cq);
  }
  
  static void nvmet_rdma_free_queue(struct nvmet_rdma_queue *queue)
  {
  	pr_info("freeing queue %d\n", queue->idx);
  
  	nvmet_sq_destroy(&queue->nvme_sq);
  
  	nvmet_rdma_destroy_queue_ib(queue);
  	if (!queue->dev->srq) {
  		nvmet_rdma_free_cmds(queue->dev, queue->cmds,
  				queue->recv_queue_size,
  				!queue->host_qid);
  	}
  	nvmet_rdma_free_rsps(queue);
  	ida_simple_remove(&nvmet_rdma_queue_ida, queue->idx);
  	kfree(queue);
  }
  
  static void nvmet_rdma_release_queue_work(struct work_struct *w)
  {
  	struct nvmet_rdma_queue *queue =
  		container_of(w, struct nvmet_rdma_queue, release_work);
  	struct rdma_cm_id *cm_id = queue->cm_id;
  	struct nvmet_rdma_device *dev = queue->dev;
  	enum nvmet_rdma_queue_state state = queue->state;
  
  	nvmet_rdma_free_queue(queue);
  
  	if (state != NVMET_RDMA_IN_DEVICE_REMOVAL)
  		rdma_destroy_id(cm_id);
  
  	kref_put(&dev->ref, nvmet_rdma_free_dev);
  }
  
  static int
  nvmet_rdma_parse_cm_connect_req(struct rdma_conn_param *conn,
  				struct nvmet_rdma_queue *queue)
  {
  	struct nvme_rdma_cm_req *req;
  
  	req = (struct nvme_rdma_cm_req *)conn->private_data;
  	if (!req || conn->private_data_len == 0)
  		return NVME_RDMA_CM_INVALID_LEN;
  
  	if (le16_to_cpu(req->recfmt) != NVME_RDMA_CM_FMT_1_0)
  		return NVME_RDMA_CM_INVALID_RECFMT;
  
  	queue->host_qid = le16_to_cpu(req->qid);
  
  	/*
  	 * req->hsqsize corresponds to our recv queue size plus 1
  	 * req->hrqsize corresponds to our send queue size
  	 */
  	queue->recv_queue_size = le16_to_cpu(req->hsqsize) + 1;
  	queue->send_queue_size = le16_to_cpu(req->hrqsize);
  
  	if (!queue->host_qid && queue->recv_queue_size > NVMF_AQ_DEPTH)
  		return NVME_RDMA_CM_INVALID_HSQSIZE;
  
  	/* XXX: Should we enforce some kind of max for IO queues? */
  
  	return 0;
  }
  
  static int nvmet_rdma_cm_reject(struct rdma_cm_id *cm_id,
  				enum nvme_rdma_cm_status status)
  {
  	struct nvme_rdma_cm_rej rej;
  
  	rej.recfmt = cpu_to_le16(NVME_RDMA_CM_FMT_1_0);
  	rej.sts = cpu_to_le16(status);
  
  	return rdma_reject(cm_id, (void *)&rej, sizeof(rej));
  }
  
  static struct nvmet_rdma_queue *
  nvmet_rdma_alloc_queue(struct nvmet_rdma_device *ndev,
  		struct rdma_cm_id *cm_id,
  		struct rdma_cm_event *event)
  {
  	struct nvmet_rdma_queue *queue;
  	int ret;
  
  	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
  	if (!queue) {
  		ret = NVME_RDMA_CM_NO_RSC;
  		goto out_reject;
  	}
  
  	ret = nvmet_sq_init(&queue->nvme_sq);
  	if (ret)
  		goto out_free_queue;
  
  	ret = nvmet_rdma_parse_cm_connect_req(&event->param.conn, queue);
  	if (ret)
  		goto out_destroy_sq;
  
  	/*
  	 * Schedules the actual release because calling rdma_destroy_id from
  	 * inside a CM callback would trigger a deadlock. (great API design..)
  	 */
  	INIT_WORK(&queue->release_work, nvmet_rdma_release_queue_work);
  	queue->dev = ndev;
  	queue->cm_id = cm_id;
  
  	spin_lock_init(&queue->state_lock);
  	queue->state = NVMET_RDMA_Q_CONNECTING;
  	INIT_LIST_HEAD(&queue->rsp_wait_list);
  	INIT_LIST_HEAD(&queue->rsp_wr_wait_list);
  	spin_lock_init(&queue->rsp_wr_wait_lock);
  	INIT_LIST_HEAD(&queue->free_rsps);
  	spin_lock_init(&queue->rsps_lock);
  	INIT_LIST_HEAD(&queue->queue_list);
  
  	queue->idx = ida_simple_get(&nvmet_rdma_queue_ida, 0, 0, GFP_KERNEL);
  	if (queue->idx < 0) {
  		ret = NVME_RDMA_CM_NO_RSC;
  		goto out_free_queue;
  	}
  
  	ret = nvmet_rdma_alloc_rsps(queue);
  	if (ret) {
  		ret = NVME_RDMA_CM_NO_RSC;
  		goto out_ida_remove;
  	}
  
  	if (!ndev->srq) {
  		queue->cmds = nvmet_rdma_alloc_cmds(ndev,
  				queue->recv_queue_size,
  				!queue->host_qid);
  		if (IS_ERR(queue->cmds)) {
  			ret = NVME_RDMA_CM_NO_RSC;
  			goto out_free_responses;
  		}
  	}
  
  	ret = nvmet_rdma_create_queue_ib(queue);
  	if (ret) {
  		pr_err("%s: creating RDMA queue failed (%d).\n",
  			__func__, ret);
  		ret = NVME_RDMA_CM_NO_RSC;
  		goto out_free_cmds;
  	}
  
  	return queue;
  
  out_free_cmds:
  	if (!ndev->srq) {
  		nvmet_rdma_free_cmds(queue->dev, queue->cmds,
  				queue->recv_queue_size,
  				!queue->host_qid);
  	}
  out_free_responses:
  	nvmet_rdma_free_rsps(queue);
  out_ida_remove:
  	ida_simple_remove(&nvmet_rdma_queue_ida, queue->idx);
  out_destroy_sq:
  	nvmet_sq_destroy(&queue->nvme_sq);
  out_free_queue:
  	kfree(queue);
  out_reject:
  	nvmet_rdma_cm_reject(cm_id, ret);
  	return NULL;
  }
  
  static void nvmet_rdma_qp_event(struct ib_event *event, void *priv)
  {
  	struct nvmet_rdma_queue *queue = priv;
  
  	switch (event->event) {
  	case IB_EVENT_COMM_EST:
  		rdma_notify(queue->cm_id, event->event);
  		break;
  	default:
  		pr_err("received unrecognized IB QP event %d\n", event->event);
  		break;
  	}
  }
  
  static int nvmet_rdma_cm_accept(struct rdma_cm_id *cm_id,
  		struct nvmet_rdma_queue *queue,
  		struct rdma_conn_param *p)
  {
  	struct rdma_conn_param  param = { };
  	struct nvme_rdma_cm_rep priv = { };
  	int ret = -ENOMEM;
  
  	param.rnr_retry_count = 7;
  	param.flow_control = 1;
  	param.initiator_depth = min_t(u8, p->initiator_depth,
  		queue->dev->device->attrs.max_qp_init_rd_atom);
  	param.private_data = &priv;
  	param.private_data_len = sizeof(priv);
  	priv.recfmt = cpu_to_le16(NVME_RDMA_CM_FMT_1_0);
  	priv.crqsize = cpu_to_le16(queue->recv_queue_size);
  
  	ret = rdma_accept(cm_id, &param);
  	if (ret)
  		pr_err("rdma_accept failed (error code = %d)\n", ret);
  
  	return ret;
  }
  
  static int nvmet_rdma_queue_connect(struct rdma_cm_id *cm_id,
  		struct rdma_cm_event *event)
  {
  	struct nvmet_rdma_device *ndev;
  	struct nvmet_rdma_queue *queue;
  	int ret = -EINVAL;
  
  	ndev = nvmet_rdma_find_get_device(cm_id);
  	if (!ndev) {
  		pr_err("no client data!\n");
  		nvmet_rdma_cm_reject(cm_id, NVME_RDMA_CM_NO_RSC);
  		return -ECONNREFUSED;
  	}
  
  	queue = nvmet_rdma_alloc_queue(ndev, cm_id, event);
  	if (!queue) {
  		ret = -ENOMEM;
  		goto put_device;
  	}
  	queue->port = cm_id->context;
  
  	ret = nvmet_rdma_cm_accept(cm_id, queue, &event->param.conn);
  	if (ret)
  		goto release_queue;
  
  	mutex_lock(&nvmet_rdma_queue_mutex);
  	list_add_tail(&queue->queue_list, &nvmet_rdma_queue_list);
  	mutex_unlock(&nvmet_rdma_queue_mutex);
  
  	return 0;
  
  release_queue:
  	nvmet_rdma_free_queue(queue);
  put_device:
  	kref_put(&ndev->ref, nvmet_rdma_free_dev);
  
  	return ret;
  }
  
  static void nvmet_rdma_queue_established(struct nvmet_rdma_queue *queue)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&queue->state_lock, flags);
  	if (queue->state != NVMET_RDMA_Q_CONNECTING) {
  		pr_warn("trying to establish a connected queue\n");
  		goto out_unlock;
  	}
  	queue->state = NVMET_RDMA_Q_LIVE;
  
  	while (!list_empty(&queue->rsp_wait_list)) {
  		struct nvmet_rdma_rsp *cmd;
  
  		cmd = list_first_entry(&queue->rsp_wait_list,
  					struct nvmet_rdma_rsp, wait_list);
  		list_del(&cmd->wait_list);
  
  		spin_unlock_irqrestore(&queue->state_lock, flags);
  		nvmet_rdma_handle_command(queue, cmd);
  		spin_lock_irqsave(&queue->state_lock, flags);
  	}
  
  out_unlock:
  	spin_unlock_irqrestore(&queue->state_lock, flags);
  }
  
  static void __nvmet_rdma_queue_disconnect(struct nvmet_rdma_queue *queue)
  {
  	bool disconnect = false;
  	unsigned long flags;
  
  	pr_debug("cm_id= %p queue->state= %d\n", queue->cm_id, queue->state);
  
  	spin_lock_irqsave(&queue->state_lock, flags);
  	switch (queue->state) {
  	case NVMET_RDMA_Q_CONNECTING:
  	case NVMET_RDMA_Q_LIVE:
  		queue->state = NVMET_RDMA_Q_DISCONNECTING;
  	case NVMET_RDMA_IN_DEVICE_REMOVAL:
  		disconnect = true;
  		break;
  	case NVMET_RDMA_Q_DISCONNECTING:
  		break;
  	}
  	spin_unlock_irqrestore(&queue->state_lock, flags);
  
  	if (disconnect) {
  		rdma_disconnect(queue->cm_id);
  		schedule_work(&queue->release_work);
  	}
  }
  
  static void nvmet_rdma_queue_disconnect(struct nvmet_rdma_queue *queue)
  {
  	bool disconnect = false;
  
  	mutex_lock(&nvmet_rdma_queue_mutex);
  	if (!list_empty(&queue->queue_list)) {
  		list_del_init(&queue->queue_list);
  		disconnect = true;
  	}
  	mutex_unlock(&nvmet_rdma_queue_mutex);
  
  	if (disconnect)
  		__nvmet_rdma_queue_disconnect(queue);
  }
  
  static void nvmet_rdma_queue_connect_fail(struct rdma_cm_id *cm_id,
  		struct nvmet_rdma_queue *queue)
  {
  	WARN_ON_ONCE(queue->state != NVMET_RDMA_Q_CONNECTING);
  
  	mutex_lock(&nvmet_rdma_queue_mutex);
  	if (!list_empty(&queue->queue_list))
  		list_del_init(&queue->queue_list);
  	mutex_unlock(&nvmet_rdma_queue_mutex);
  
  	pr_err("failed to connect queue %d\n", queue->idx);
  	schedule_work(&queue->release_work);
  }
  
  /**
   * nvme_rdma_device_removal() - Handle RDMA device removal
   * @queue:      nvmet rdma queue (cm id qp_context)
   * @addr:	nvmet address (cm_id context)
   *
   * DEVICE_REMOVAL event notifies us that the RDMA device is about
   * to unplug so we should take care of destroying our RDMA resources.
   * This event will be generated for each allocated cm_id.
   *
   * Note that this event can be generated on a normal queue cm_id
   * and/or a device bound listener cm_id (where in this case
   * queue will be null).
   *
   * we claim ownership on destroying the cm_id. For queues we move
   * the queue state to NVMET_RDMA_IN_DEVICE_REMOVAL and for port
   * we nullify the priv to prevent double cm_id destruction and destroying
   * the cm_id implicitely by returning a non-zero rc to the callout.
   */
  static int nvmet_rdma_device_removal(struct rdma_cm_id *cm_id,
  		struct nvmet_rdma_queue *queue)
  {
  	unsigned long flags;
  
  	if (!queue) {
  		struct nvmet_port *port = cm_id->context;
  
  		/*
  		 * This is a listener cm_id. Make sure that
  		 * future remove_port won't invoke a double
  		 * cm_id destroy. use atomic xchg to make sure
  		 * we don't compete with remove_port.
  		 */
  		if (xchg(&port->priv, NULL) != cm_id)
  			return 0;
  	} else {
  		/*
  		 * This is a queue cm_id. Make sure that
  		 * release queue will not destroy the cm_id
  		 * and schedule all ctrl queues removal (only
  		 * if the queue is not disconnecting already).
  		 */
  		spin_lock_irqsave(&queue->state_lock, flags);
  		if (queue->state != NVMET_RDMA_Q_DISCONNECTING)
  			queue->state = NVMET_RDMA_IN_DEVICE_REMOVAL;
  		spin_unlock_irqrestore(&queue->state_lock, flags);
  		nvmet_rdma_queue_disconnect(queue);
  		flush_scheduled_work();
  	}
  
  	/*
  	 * We need to return 1 so that the core will destroy
  	 * it's own ID.  What a great API design..
  	 */
  	return 1;
  }
  
  static int nvmet_rdma_cm_handler(struct rdma_cm_id *cm_id,
  		struct rdma_cm_event *event)
  {
  	struct nvmet_rdma_queue *queue = NULL;
  	int ret = 0;
  
  	if (cm_id->qp)
  		queue = cm_id->qp->qp_context;
  
  	pr_debug("%s (%d): status %d id %p\n",
  		rdma_event_msg(event->event), event->event,
  		event->status, cm_id);
  
  	switch (event->event) {
  	case RDMA_CM_EVENT_CONNECT_REQUEST:
  		ret = nvmet_rdma_queue_connect(cm_id, event);
  		break;
  	case RDMA_CM_EVENT_ESTABLISHED:
  		nvmet_rdma_queue_established(queue);
  		break;
  	case RDMA_CM_EVENT_ADDR_CHANGE:
  	case RDMA_CM_EVENT_DISCONNECTED:
  	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
  		/*
  		 * We might end up here when we already freed the qp
  		 * which means queue release sequence is in progress,
  		 * so don't get in the way...
  		 */
  		if (queue)
  			nvmet_rdma_queue_disconnect(queue);
  		break;
  	case RDMA_CM_EVENT_DEVICE_REMOVAL:
  		ret = nvmet_rdma_device_removal(cm_id, queue);
  		break;
  	case RDMA_CM_EVENT_REJECTED:
  	case RDMA_CM_EVENT_UNREACHABLE:
  	case RDMA_CM_EVENT_CONNECT_ERROR:
  		nvmet_rdma_queue_connect_fail(cm_id, queue);
  		break;
  	default:
  		pr_err("received unrecognized RDMA CM event %d\n",
  			event->event);
  		break;
  	}
  
  	return ret;
  }
  
  static void nvmet_rdma_delete_ctrl(struct nvmet_ctrl *ctrl)
  {
  	struct nvmet_rdma_queue *queue;
  
  restart:
  	mutex_lock(&nvmet_rdma_queue_mutex);
  	list_for_each_entry(queue, &nvmet_rdma_queue_list, queue_list) {
  		if (queue->nvme_sq.ctrl == ctrl) {
  			list_del_init(&queue->queue_list);
  			mutex_unlock(&nvmet_rdma_queue_mutex);
  
  			__nvmet_rdma_queue_disconnect(queue);
  			goto restart;
  		}
  	}
  	mutex_unlock(&nvmet_rdma_queue_mutex);
  }
  
  static int nvmet_rdma_add_port(struct nvmet_port *port)
  {
  	struct rdma_cm_id *cm_id;
  	struct sockaddr_in addr_in;
  	u16 port_in;
  	int ret;
  
  	switch (port->disc_addr.adrfam) {
  	case NVMF_ADDR_FAMILY_IP4:
  		break;
  	default:
  		pr_err("address family %d not supported\n",
  				port->disc_addr.adrfam);
  		return -EINVAL;
  	}
  
  	ret = kstrtou16(port->disc_addr.trsvcid, 0, &port_in);
  	if (ret)
  		return ret;
  
  	addr_in.sin_family = AF_INET;
  	addr_in.sin_addr.s_addr = in_aton(port->disc_addr.traddr);
  	addr_in.sin_port = htons(port_in);
  
  	cm_id = rdma_create_id(&init_net, nvmet_rdma_cm_handler, port,
  			RDMA_PS_TCP, IB_QPT_RC);
  	if (IS_ERR(cm_id)) {
  		pr_err("CM ID creation failed\n");
  		return PTR_ERR(cm_id);
  	}
  
  	ret = rdma_bind_addr(cm_id, (struct sockaddr *)&addr_in);
  	if (ret) {
  		pr_err("binding CM ID to %pISpc failed (%d)\n", &addr_in, ret);
  		goto out_destroy_id;
  	}
  
  	ret = rdma_listen(cm_id, 128);
  	if (ret) {
  		pr_err("listening to %pISpc failed (%d)\n", &addr_in, ret);
  		goto out_destroy_id;
  	}
  
  	pr_info("enabling port %d (%pISpc)\n",
  		le16_to_cpu(port->disc_addr.portid), &addr_in);
  	port->priv = cm_id;
  	return 0;
  
  out_destroy_id:
  	rdma_destroy_id(cm_id);
  	return ret;
  }
  
  static void nvmet_rdma_remove_port(struct nvmet_port *port)
  {
  	struct rdma_cm_id *cm_id = xchg(&port->priv, NULL);
  
  	if (cm_id)
  		rdma_destroy_id(cm_id);
  }
  
  static struct nvmet_fabrics_ops nvmet_rdma_ops = {
  	.owner			= THIS_MODULE,
  	.type			= NVMF_TRTYPE_RDMA,
  	.sqe_inline_size	= NVMET_RDMA_INLINE_DATA_SIZE,
  	.msdbd			= 1,
  	.has_keyed_sgls		= 1,
  	.add_port		= nvmet_rdma_add_port,
  	.remove_port		= nvmet_rdma_remove_port,
  	.queue_response		= nvmet_rdma_queue_response,
  	.delete_ctrl		= nvmet_rdma_delete_ctrl,
  };
  
  static int __init nvmet_rdma_init(void)
  {
  	return nvmet_register_transport(&nvmet_rdma_ops);
  }
  
  static void __exit nvmet_rdma_exit(void)
  {
  	struct nvmet_rdma_queue *queue;
  
  	nvmet_unregister_transport(&nvmet_rdma_ops);
  
  	flush_scheduled_work();
  
  	mutex_lock(&nvmet_rdma_queue_mutex);
  	while ((queue = list_first_entry_or_null(&nvmet_rdma_queue_list,
  			struct nvmet_rdma_queue, queue_list))) {
  		list_del_init(&queue->queue_list);
  
  		mutex_unlock(&nvmet_rdma_queue_mutex);
  		__nvmet_rdma_queue_disconnect(queue);
  		mutex_lock(&nvmet_rdma_queue_mutex);
  	}
  	mutex_unlock(&nvmet_rdma_queue_mutex);
  
  	flush_scheduled_work();
  	ida_destroy(&nvmet_rdma_queue_ida);
  }
  
  module_init(nvmet_rdma_init);
  module_exit(nvmet_rdma_exit);
  
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS("nvmet-transport-1"); /* 1 == NVMF_TRTYPE_RDMA */
  