/*
   * Copyright (c) 2016 Oracle.  All rights reserved.
   *
   * This software is available to you under a choice of one of two
   * licenses.  You may choose to be licensed under the terms of the GNU
   * General Public License (GPL) Version 2, available from the file
   * COPYING in the main directory of this source tree, or the
   * OpenIB.org BSD license below:
   *
   *     Redistribution and use in source and binary forms, with or
   *     without modification, are permitted provided that the following
   *     conditions are met:
   *
   *      - Redistributions of source code must retain the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer.
   *
   *      - Redistributions in binary form must reproduce the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer in the documentation and/or other materials
   *        provided with the distribution.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  #include "ib_mr.h"

  static inline void
  rds_transition_frwr_state(struct rds_ib_mr *ibmr,
  			  enum rds_ib_fr_state old_state,
  			  enum rds_ib_fr_state new_state)
  {
  	if (cmpxchg(&ibmr->u.frmr.fr_state,
  		    old_state, new_state) == old_state &&
  	    old_state == FRMR_IS_INUSE) {
  		/* enforce order of ibmr->u.frmr.fr_state update
  		 * before decrementing i_fastreg_inuse_count
  		 */
  		smp_mb__before_atomic();
  		atomic_dec(&ibmr->ic->i_fastreg_inuse_count);
  		if (waitqueue_active(&rds_ib_ring_empty_wait))
  			wake_up(&rds_ib_ring_empty_wait);
  	}
  }

  static struct rds_ib_mr *rds_ib_alloc_frmr(struct rds_ib_device *rds_ibdev,
  					   int npages)
  {
  	struct rds_ib_mr_pool *pool;
  	struct rds_ib_mr *ibmr = NULL;
  	struct rds_ib_frmr *frmr;
  	int err = 0;
  
  	if (npages <= RDS_MR_8K_MSG_SIZE)
  		pool = rds_ibdev->mr_8k_pool;
  	else
  		pool = rds_ibdev->mr_1m_pool;
  
  	ibmr = rds_ib_try_reuse_ibmr(pool);
  	if (ibmr)
  		return ibmr;
  
  	ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL,
  			    rdsibdev_to_node(rds_ibdev));
  	if (!ibmr) {
  		err = -ENOMEM;
  		goto out_no_cigar;
  	}
  
  	frmr = &ibmr->u.frmr;
  	frmr->mr = ib_alloc_mr(rds_ibdev->pd, IB_MR_TYPE_MEM_REG,

  			 pool->max_pages);

  	if (IS_ERR(frmr->mr)) {
  		pr_warn("RDS/IB: %s failed to allocate MR", __func__);

  		err = PTR_ERR(frmr->mr);

  		goto out_no_cigar;
  	}
  
  	ibmr->pool = pool;
  	if (pool->pool_type == RDS_IB_MR_8K_POOL)
  		rds_ib_stats_inc(s_ib_rdma_mr_8k_alloc);
  	else
  		rds_ib_stats_inc(s_ib_rdma_mr_1m_alloc);
  
  	if (atomic_read(&pool->item_count) > pool->max_items_soft)
  		pool->max_items_soft = pool->max_items;
  
  	frmr->fr_state = FRMR_IS_FREE;

  	init_waitqueue_head(&frmr->fr_inv_done);

  	init_waitqueue_head(&frmr->fr_reg_done);

  	return ibmr;
  
  out_no_cigar:
  	kfree(ibmr);
  	atomic_dec(&pool->item_count);
  	return ERR_PTR(err);
  }
  
  static void rds_ib_free_frmr(struct rds_ib_mr *ibmr, bool drop)
  {
  	struct rds_ib_mr_pool *pool = ibmr->pool;
  
  	if (drop)
  		llist_add(&ibmr->llnode, &pool->drop_list);
  	else
  		llist_add(&ibmr->llnode, &pool->free_list);
  	atomic_add(ibmr->sg_len, &pool->free_pinned);
  	atomic_inc(&pool->dirty_count);
  
  	/* If we've pinned too many pages, request a flush */
  	if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
  	    atomic_read(&pool->dirty_count) >= pool->max_items / 5)
  		queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
  }
  
  static int rds_ib_post_reg_frmr(struct rds_ib_mr *ibmr)
  {
  	struct rds_ib_frmr *frmr = &ibmr->u.frmr;

  	struct ib_reg_wr reg_wr;

  	int ret, off = 0;

  
  	while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
  		atomic_inc(&ibmr->ic->i_fastreg_wrs);
  		cpu_relax();
  	}

  	ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_len,
  				&off, PAGE_SIZE);

  	if (unlikely(ret != ibmr->sg_len))
  		return ret < 0 ? ret : -EINVAL;

  	if (cmpxchg(&frmr->fr_state,
  		    FRMR_IS_FREE, FRMR_IS_INUSE) != FRMR_IS_FREE)
  		return -EBUSY;
  
  	atomic_inc(&ibmr->ic->i_fastreg_inuse_count);

  	/* Perform a WR for the fast_reg_mr. Each individual page
  	 * in the sg list is added to the fast reg page list and placed
  	 * inside the fast_reg_mr WR.  The key used is a rolling 8bit
  	 * counter, which should guarantee uniqueness.
  	 */
  	ib_update_fast_reg_key(frmr->mr, ibmr->remap_count++);

  	frmr->fr_reg = true;

  
  	memset(&reg_wr, 0, sizeof(reg_wr));
  	reg_wr.wr.wr_id = (unsigned long)(void *)ibmr;
  	reg_wr.wr.opcode = IB_WR_REG_MR;
  	reg_wr.wr.num_sge = 0;
  	reg_wr.mr = frmr->mr;
  	reg_wr.key = frmr->mr->rkey;
  	reg_wr.access = IB_ACCESS_LOCAL_WRITE |
  			IB_ACCESS_REMOTE_READ |
  			IB_ACCESS_REMOTE_WRITE;
  	reg_wr.wr.send_flags = IB_SEND_SIGNALED;

  	ret = ib_post_send(ibmr->ic->i_cm_id->qp, &reg_wr.wr, NULL);

  	if (unlikely(ret)) {
  		/* Failure here can be because of -ENOMEM as well */

  		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);

  		atomic_inc(&ibmr->ic->i_fastreg_wrs);
  		if (printk_ratelimit())
  			pr_warn("RDS/IB: %s returned error(%d)
  ",
  				__func__, ret);

  		goto out;

  	}

  
  	/* Wait for the registration to complete in order to prevent an invalid
  	 * access error resulting from a race between the memory region already
  	 * being accessed while registration is still pending.
  	 */
  	wait_event(frmr->fr_reg_done, !frmr->fr_reg);
  
  out:

  	return ret;
  }
  
  static int rds_ib_map_frmr(struct rds_ib_device *rds_ibdev,
  			   struct rds_ib_mr_pool *pool,
  			   struct rds_ib_mr *ibmr,
  			   struct scatterlist *sg, unsigned int sg_len)
  {
  	struct ib_device *dev = rds_ibdev->dev;
  	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
  	int i;
  	u32 len;
  	int ret = 0;
  
  	/* We want to teardown old ibmr values here and fill it up with
  	 * new sg values
  	 */
  	rds_ib_teardown_mr(ibmr);
  
  	ibmr->sg = sg;
  	ibmr->sg_len = sg_len;
  	ibmr->sg_dma_len = 0;
  	frmr->sg_byte_len = 0;
  	WARN_ON(ibmr->sg_dma_len);
  	ibmr->sg_dma_len = ib_dma_map_sg(dev, ibmr->sg, ibmr->sg_len,
  					 DMA_BIDIRECTIONAL);
  	if (unlikely(!ibmr->sg_dma_len)) {
  		pr_warn("RDS/IB: %s failed!
  ", __func__);
  		return -EBUSY;
  	}
  
  	frmr->sg_byte_len = 0;
  	frmr->dma_npages = 0;
  	len = 0;
  
  	ret = -EINVAL;
  	for (i = 0; i < ibmr->sg_dma_len; ++i) {

  		unsigned int dma_len = sg_dma_len(&ibmr->sg[i]);
  		u64 dma_addr = sg_dma_address(&ibmr->sg[i]);

  
  		frmr->sg_byte_len += dma_len;
  		if (dma_addr & ~PAGE_MASK) {
  			if (i > 0)
  				goto out_unmap;
  			else
  				++frmr->dma_npages;
  		}
  
  		if ((dma_addr + dma_len) & ~PAGE_MASK) {
  			if (i < ibmr->sg_dma_len - 1)
  				goto out_unmap;
  			else
  				++frmr->dma_npages;
  		}
  
  		len += dma_len;
  	}
  	frmr->dma_npages += len >> PAGE_SHIFT;

  	if (frmr->dma_npages > ibmr->pool->max_pages) {

  		ret = -EMSGSIZE;
  		goto out_unmap;
  	}
  
  	ret = rds_ib_post_reg_frmr(ibmr);
  	if (ret)
  		goto out_unmap;
  
  	if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
  		rds_ib_stats_inc(s_ib_rdma_mr_8k_used);
  	else
  		rds_ib_stats_inc(s_ib_rdma_mr_1m_used);
  
  	return ret;
  
  out_unmap:
  	ib_dma_unmap_sg(rds_ibdev->dev, ibmr->sg, ibmr->sg_len,
  			DMA_BIDIRECTIONAL);
  	ibmr->sg_dma_len = 0;
  	return ret;
  }
  
  static int rds_ib_post_inv(struct rds_ib_mr *ibmr)
  {

  	struct ib_send_wr *s_wr;

  	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
  	struct rdma_cm_id *i_cm_id = ibmr->ic->i_cm_id;
  	int ret = -EINVAL;
  
  	if (!i_cm_id || !i_cm_id->qp || !frmr->mr)
  		goto out;
  
  	if (frmr->fr_state != FRMR_IS_INUSE)
  		goto out;

  	while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
  		atomic_inc(&ibmr->ic->i_fastreg_wrs);

  		cpu_relax();
  	}
  
  	frmr->fr_inv = true;
  	s_wr = &frmr->fr_wr;
  
  	memset(s_wr, 0, sizeof(*s_wr));
  	s_wr->wr_id = (unsigned long)(void *)ibmr;
  	s_wr->opcode = IB_WR_LOCAL_INV;
  	s_wr->ex.invalidate_rkey = frmr->mr->rkey;
  	s_wr->send_flags = IB_SEND_SIGNALED;

  	ret = ib_post_send(i_cm_id->qp, s_wr, NULL);

  	if (unlikely(ret)) {

  		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);

  		frmr->fr_inv = false;

  		/* enforce order of frmr->fr_inv update
  		 * before incrementing i_fastreg_wrs
  		 */
  		smp_mb__before_atomic();

  		atomic_inc(&ibmr->ic->i_fastreg_wrs);

  		pr_err("RDS/IB: %s returned error(%d)
  ", __func__, ret);
  		goto out;
  	}

  
  	/* Wait for the FRMR_IS_FREE (or FRMR_IS_STALE) transition in order to
  	 * 1) avoid a silly bouncing between "clean_list" and "drop_list"
  	 *    triggered by function "rds_ib_reg_frmr" as it is releases frmr
  	 *    regions whose state is not "FRMR_IS_FREE" right away.
  	 * 2) prevents an invalid access error in a race
  	 *    from a pending "IB_WR_LOCAL_INV" operation
  	 *    with a teardown ("dma_unmap_sg", "put_page")
  	 *    and de-registration ("ib_dereg_mr") of the corresponding
  	 *    memory region.
  	 */
  	wait_event(frmr->fr_inv_done, frmr->fr_state != FRMR_IS_INUSE);

  out:
  	return ret;
  }
  
  void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
  {
  	struct rds_ib_mr *ibmr = (void *)(unsigned long)wc->wr_id;
  	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
  
  	if (wc->status != IB_WC_SUCCESS) {

  		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);

  		if (rds_conn_up(ic->conn))
  			rds_ib_conn_error(ic->conn,
  					  "frmr completion <%pI4,%pI4> status %u(%s), vendor_err 0x%x, disconnecting and reconnecting
  ",
  					  &ic->conn->c_laddr,
  					  &ic->conn->c_faddr,
  					  wc->status,
  					  ib_wc_status_msg(wc->status),
  					  wc->vendor_err);
  	}
  
  	if (frmr->fr_inv) {

  		rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_FREE);

  		frmr->fr_inv = false;

  		wake_up(&frmr->fr_inv_done);

  	}

  	if (frmr->fr_reg) {
  		frmr->fr_reg = false;
  		wake_up(&frmr->fr_reg_done);
  	}

  	/* enforce order of frmr->{fr_reg,fr_inv} update
  	 * before incrementing i_fastreg_wrs
  	 */
  	smp_mb__before_atomic();

  	atomic_inc(&ic->i_fastreg_wrs);

  }
  
  void rds_ib_unreg_frmr(struct list_head *list, unsigned int *nfreed,
  		       unsigned long *unpinned, unsigned int goal)
  {
  	struct rds_ib_mr *ibmr, *next;
  	struct rds_ib_frmr *frmr;

  	int ret = 0, ret2;

  	unsigned int freed = *nfreed;
  
  	/* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
  	list_for_each_entry(ibmr, list, unmap_list) {

  		if (ibmr->sg_dma_len) {
  			ret2 = rds_ib_post_inv(ibmr);
  			if (ret2 && !ret)
  				ret = ret2;
  		}

  	}

  	if (ret)
  		pr_warn("RDS/IB: %s failed (err=%d)
  ", __func__, ret);
  
  	/* Now we can destroy the DMA mapping and unpin any pages */
  	list_for_each_entry_safe(ibmr, next, list, unmap_list) {
  		*unpinned += ibmr->sg_len;
  		frmr = &ibmr->u.frmr;
  		__rds_ib_teardown_mr(ibmr);
  		if (freed < goal || frmr->fr_state == FRMR_IS_STALE) {
  			/* Don't de-allocate if the MR is not free yet */
  			if (frmr->fr_state == FRMR_IS_INUSE)
  				continue;
  
  			if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
  				rds_ib_stats_inc(s_ib_rdma_mr_8k_free);
  			else
  				rds_ib_stats_inc(s_ib_rdma_mr_1m_free);
  			list_del(&ibmr->unmap_list);
  			if (frmr->mr)
  				ib_dereg_mr(frmr->mr);
  			kfree(ibmr);
  			freed++;
  		}
  	}
  	*nfreed = freed;
  }
  
  struct rds_ib_mr *rds_ib_reg_frmr(struct rds_ib_device *rds_ibdev,
  				  struct rds_ib_connection *ic,
  				  struct scatterlist *sg,
  				  unsigned long nents, u32 *key)
  {
  	struct rds_ib_mr *ibmr = NULL;
  	struct rds_ib_frmr *frmr;
  	int ret;

  	if (!ic) {
  		/* TODO: Add FRWR support for RDS_GET_MR using proxy qp*/
  		return ERR_PTR(-EOPNOTSUPP);
  	}

  	do {

  		if (ibmr)

  			rds_ib_free_frmr(ibmr, true);
  		ibmr = rds_ib_alloc_frmr(rds_ibdev, nents);
  		if (IS_ERR(ibmr))
  			return ibmr;
  		frmr = &ibmr->u.frmr;
  	} while (frmr->fr_state != FRMR_IS_FREE);
  
  	ibmr->ic = ic;
  	ibmr->device = rds_ibdev;
  	ret = rds_ib_map_frmr(rds_ibdev, ibmr->pool, ibmr, sg, nents);
  	if (ret == 0) {
  		*key = frmr->mr->rkey;
  	} else {
  		rds_ib_free_frmr(ibmr, false);
  		ibmr = ERR_PTR(ret);
  	}
  
  	return ibmr;
  }
  
  void rds_ib_free_frmr_list(struct rds_ib_mr *ibmr)
  {
  	struct rds_ib_mr_pool *pool = ibmr->pool;
  	struct rds_ib_frmr *frmr = &ibmr->u.frmr;
  
  	if (frmr->fr_state == FRMR_IS_STALE)
  		llist_add(&ibmr->llnode, &pool->drop_list);
  	else
  		llist_add(&ibmr->llnode, &pool->free_list);
  }