/*
   * Copyright (c) 2006 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 <linux/kernel.h>

  #include <linux/slab.h>

  #include <linux/rculist.h>

  #include <linux/llist.h>

  #include "rds_single_path.h"

  #include "ib_mr.h"
  
  struct workqueue_struct *rds_ib_mr_wq;

  static DEFINE_PER_CPU(unsigned long, clean_list_grace);
  #define CLEAN_LIST_BUSY_BIT 0

  static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
  {
  	struct rds_ib_device *rds_ibdev;
  	struct rds_ib_ipaddr *i_ipaddr;

  	rcu_read_lock();
  	list_for_each_entry_rcu(rds_ibdev, &rds_ib_devices, list) {

  		list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {

  			if (i_ipaddr->ipaddr == ipaddr) {

  				refcount_inc(&rds_ibdev->refcount);

  				rcu_read_unlock();

  				return rds_ibdev;
  			}
  		}

  	}

  	rcu_read_unlock();

  
  	return NULL;
  }
  
  static int rds_ib_add_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
  {
  	struct rds_ib_ipaddr *i_ipaddr;
  
  	i_ipaddr = kmalloc(sizeof *i_ipaddr, GFP_KERNEL);
  	if (!i_ipaddr)
  		return -ENOMEM;
  
  	i_ipaddr->ipaddr = ipaddr;
  
  	spin_lock_irq(&rds_ibdev->spinlock);

  	list_add_tail_rcu(&i_ipaddr->list, &rds_ibdev->ipaddr_list);

  	spin_unlock_irq(&rds_ibdev->spinlock);
  
  	return 0;
  }
  
  static void rds_ib_remove_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
  {

  	struct rds_ib_ipaddr *i_ipaddr;

  	struct rds_ib_ipaddr *to_free = NULL;

  
  	spin_lock_irq(&rds_ibdev->spinlock);

  	list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {

  		if (i_ipaddr->ipaddr == ipaddr) {

  			list_del_rcu(&i_ipaddr->list);
  			to_free = i_ipaddr;

  			break;
  		}
  	}
  	spin_unlock_irq(&rds_ibdev->spinlock);

  	if (to_free)
  		kfree_rcu(to_free, rcu);

  }
  
  int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
  {
  	struct rds_ib_device *rds_ibdev_old;
  
  	rds_ibdev_old = rds_ib_get_device(ipaddr);

  	if (!rds_ibdev_old)
  		return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
  
  	if (rds_ibdev_old != rds_ibdev) {

  		rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr);

  		rds_ib_dev_put(rds_ibdev_old);

  		return rds_ib_add_ipaddr(rds_ibdev, ipaddr);

  	}

  	rds_ib_dev_put(rds_ibdev_old);

  	return 0;

  }

  void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)

  {
  	struct rds_ib_connection *ic = conn->c_transport_data;
  
  	/* conn was previously on the nodev_conns_list */
  	spin_lock_irq(&ib_nodev_conns_lock);
  	BUG_ON(list_empty(&ib_nodev_conns));
  	BUG_ON(list_empty(&ic->ib_node));
  	list_del(&ic->ib_node);

  	spin_lock(&rds_ibdev->spinlock);

  	list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);

  	spin_unlock(&rds_ibdev->spinlock);

  	spin_unlock_irq(&ib_nodev_conns_lock);

  
  	ic->rds_ibdev = rds_ibdev;

  	refcount_inc(&rds_ibdev->refcount);

  }

  void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)

  {

  	struct rds_ib_connection *ic = conn->c_transport_data;

  	/* place conn on nodev_conns_list */
  	spin_lock(&ib_nodev_conns_lock);

  	spin_lock_irq(&rds_ibdev->spinlock);
  	BUG_ON(list_empty(&ic->ib_node));
  	list_del(&ic->ib_node);
  	spin_unlock_irq(&rds_ibdev->spinlock);
  
  	list_add_tail(&ic->ib_node, &ib_nodev_conns);
  
  	spin_unlock(&ib_nodev_conns_lock);
  
  	ic->rds_ibdev = NULL;

  	rds_ib_dev_put(rds_ibdev);

  }

  void rds_ib_destroy_nodev_conns(void)

  {
  	struct rds_ib_connection *ic, *_ic;
  	LIST_HEAD(tmp_list);
  
  	/* avoid calling conn_destroy with irqs off */

  	spin_lock_irq(&ib_nodev_conns_lock);
  	list_splice(&ib_nodev_conns, &tmp_list);
  	spin_unlock_irq(&ib_nodev_conns_lock);

  	list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node)

  		rds_conn_destroy(ic->conn);

  }

  void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo)
  {

  	struct rds_ib_mr_pool *pool_1m = rds_ibdev->mr_1m_pool;

  	iinfo->rdma_mr_max = pool_1m->max_items;
  	iinfo->rdma_mr_size = pool_1m->fmr_attr.max_pages;

  }

  struct rds_ib_mr *rds_ib_reuse_mr(struct rds_ib_mr_pool *pool)

  {
  	struct rds_ib_mr *ibmr = NULL;

  	struct llist_node *ret;

  	unsigned long *flag;

  	preempt_disable();

  	flag = this_cpu_ptr(&clean_list_grace);

  	set_bit(CLEAN_LIST_BUSY_BIT, flag);

  	ret = llist_del_first(&pool->clean_list);

  	if (ret) {

  		ibmr = llist_entry(ret, struct rds_ib_mr, llnode);

  		if (pool->pool_type == RDS_IB_MR_8K_POOL)
  			rds_ib_stats_inc(s_ib_rdma_mr_8k_reused);
  		else
  			rds_ib_stats_inc(s_ib_rdma_mr_1m_reused);
  	}

  	clear_bit(CLEAN_LIST_BUSY_BIT, flag);
  	preempt_enable();

  	return ibmr;
  }

  static inline void wait_clean_list_grace(void)
  {
  	int cpu;
  	unsigned long *flag;
  
  	for_each_online_cpu(cpu) {
  		flag = &per_cpu(clean_list_grace, cpu);
  		while (test_bit(CLEAN_LIST_BUSY_BIT, flag))
  			cpu_relax();
  	}
  }

  void rds_ib_sync_mr(void *trans_private, int direction)
  {
  	struct rds_ib_mr *ibmr = trans_private;
  	struct rds_ib_device *rds_ibdev = ibmr->device;
  
  	switch (direction) {
  	case DMA_FROM_DEVICE:
  		ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
  			ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
  		break;
  	case DMA_TO_DEVICE:
  		ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
  			ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
  		break;
  	}
  }

  void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)

  {
  	struct rds_ib_device *rds_ibdev = ibmr->device;
  
  	if (ibmr->sg_dma_len) {
  		ib_dma_unmap_sg(rds_ibdev->dev,
  				ibmr->sg, ibmr->sg_len,
  				DMA_BIDIRECTIONAL);
  		ibmr->sg_dma_len = 0;
  	}
  
  	/* Release the s/g list */
  	if (ibmr->sg_len) {
  		unsigned int i;
  
  		for (i = 0; i < ibmr->sg_len; ++i) {
  			struct page *page = sg_page(&ibmr->sg[i]);
  
  			/* FIXME we need a way to tell a r/w MR
  			 * from a r/o MR */

  			WARN_ON(!page->mapping && irqs_disabled());

  			set_page_dirty(page);
  			put_page(page);
  		}
  		kfree(ibmr->sg);
  
  		ibmr->sg = NULL;
  		ibmr->sg_len = 0;
  	}
  }

  void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)

  {
  	unsigned int pinned = ibmr->sg_len;
  
  	__rds_ib_teardown_mr(ibmr);
  	if (pinned) {

  		struct rds_ib_mr_pool *pool = ibmr->pool;

  
  		atomic_sub(pinned, &pool->free_pinned);
  	}
  }
  
  static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
  {
  	unsigned int item_count;
  
  	item_count = atomic_read(&pool->item_count);
  	if (free_all)
  		return item_count;
  
  	return 0;
  }
  
  /*

   * given an llist of mrs, put them all into the list_head for more processing

   */

  static unsigned int llist_append_to_list(struct llist_head *llist,
  					 struct list_head *list)

  {
  	struct rds_ib_mr *ibmr;

  	struct llist_node *node;
  	struct llist_node *next;

  	unsigned int count = 0;

  
  	node = llist_del_all(llist);
  	while (node) {
  		next = node->next;
  		ibmr = llist_entry(node, struct rds_ib_mr, llnode);

  		list_add_tail(&ibmr->unmap_list, list);

  		node = next;

  		count++;

  	}

  	return count;

  }
  
  /*

   * this takes a list head of mrs and turns it into linked llist nodes
   * of clusters.  Each cluster has linked llist nodes of
   * MR_CLUSTER_SIZE mrs that are ready for reuse.

   */

  static void list_to_llist_nodes(struct rds_ib_mr_pool *pool,
  				struct list_head *list,
  				struct llist_node **nodes_head,
  				struct llist_node **nodes_tail)

  {
  	struct rds_ib_mr *ibmr;

  	struct llist_node *cur = NULL;
  	struct llist_node **next = nodes_head;

  
  	list_for_each_entry(ibmr, list, unmap_list) {

  		cur = &ibmr->llnode;
  		*next = cur;
  		next = &cur->next;

  	}

  	*next = NULL;
  	*nodes_tail = cur;

  }
  
  /*

   * Flush our pool of MRs.
   * At a minimum, all currently unused MRs are unmapped.
   * If the number of MRs allocated exceeds the limit, we also try
   * to free as many MRs as needed to get back to this limit.
   */

  int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
  			 int free_all, struct rds_ib_mr **ibmr_ret)

  {

  	struct rds_ib_mr *ibmr;

  	struct llist_node *clean_nodes;
  	struct llist_node *clean_tail;

  	LIST_HEAD(unmap_list);

  	unsigned long unpinned = 0;

  	unsigned int nfreed = 0, dirty_to_clean = 0, free_goal;

  	if (pool->pool_type == RDS_IB_MR_8K_POOL)
  		rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_flush);
  	else
  		rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_flush);

  	if (ibmr_ret) {
  		DEFINE_WAIT(wait);

  		while (!mutex_trylock(&pool->flush_lock)) {

  			ibmr = rds_ib_reuse_mr(pool);

  			if (ibmr) {
  				*ibmr_ret = ibmr;
  				finish_wait(&pool->flush_wait, &wait);
  				goto out_nolock;
  			}
  
  			prepare_to_wait(&pool->flush_wait, &wait,
  					TASK_UNINTERRUPTIBLE);

  			if (llist_empty(&pool->clean_list))

  				schedule();

  			ibmr = rds_ib_reuse_mr(pool);

  			if (ibmr) {
  				*ibmr_ret = ibmr;
  				finish_wait(&pool->flush_wait, &wait);
  				goto out_nolock;
  			}
  		}
  		finish_wait(&pool->flush_wait, &wait);
  	} else
  		mutex_lock(&pool->flush_lock);
  
  	if (ibmr_ret) {

  		ibmr = rds_ib_reuse_mr(pool);

  		if (ibmr) {
  			*ibmr_ret = ibmr;
  			goto out;
  		}
  	}

  	/* Get the list of all MRs to be dropped. Ordering matters -

  	 * we want to put drop_list ahead of free_list.
  	 */

  	dirty_to_clean = llist_append_to_list(&pool->drop_list, &unmap_list);
  	dirty_to_clean += llist_append_to_list(&pool->free_list, &unmap_list);

  	if (free_all)

  		llist_append_to_list(&pool->clean_list, &unmap_list);

  
  	free_goal = rds_ib_flush_goal(pool, free_all);
  
  	if (list_empty(&unmap_list))
  		goto out;

  	if (pool->use_fastreg)
  		rds_ib_unreg_frmr(&unmap_list, &nfreed, &unpinned, free_goal);
  	else
  		rds_ib_unreg_fmr(&unmap_list, &nfreed, &unpinned, free_goal);

  	if (!list_empty(&unmap_list)) {
  		/* we have to make sure that none of the things we're about
  		 * to put on the clean list would race with other cpus trying

  		 * to pull items off.  The llist would explode if we managed to

  		 * remove something from the clean list and then add it back again

  		 * while another CPU was spinning on that same item in llist_del_first.

  		 *

  		 * This is pretty unlikely, but just in case  wait for an llist grace period

  		 * here before adding anything back into the clean list.
  		 */
  		wait_clean_list_grace();

  		list_to_llist_nodes(pool, &unmap_list, &clean_nodes, &clean_tail);

  		if (ibmr_ret)

  			*ibmr_ret = llist_entry(clean_nodes, struct rds_ib_mr, llnode);

  		/* more than one entry in llist nodes */
  		if (clean_nodes->next)
  			llist_add_batch(clean_nodes->next, clean_tail, &pool->clean_list);

  
  	}

  
  	atomic_sub(unpinned, &pool->free_pinned);

  	atomic_sub(dirty_to_clean, &pool->dirty_count);

  	atomic_sub(nfreed, &pool->item_count);
  
  out:
  	mutex_unlock(&pool->flush_lock);

  	if (waitqueue_active(&pool->flush_wait))
  		wake_up(&pool->flush_wait);
  out_nolock:

  	return 0;
  }
  
  struct rds_ib_mr *rds_ib_try_reuse_ibmr(struct rds_ib_mr_pool *pool)
  {
  	struct rds_ib_mr *ibmr = NULL;
  	int iter = 0;
  
  	if (atomic_read(&pool->dirty_count) >= pool->max_items_soft / 10)
  		queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
  
  	while (1) {
  		ibmr = rds_ib_reuse_mr(pool);
  		if (ibmr)
  			return ibmr;
  
  		if (atomic_inc_return(&pool->item_count) <= pool->max_items)
  			break;
  
  		atomic_dec(&pool->item_count);
  
  		if (++iter > 2) {
  			if (pool->pool_type == RDS_IB_MR_8K_POOL)
  				rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_depleted);
  			else
  				rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_depleted);
  			return ERR_PTR(-EAGAIN);
  		}
  
  		/* We do have some empty MRs. Flush them out. */
  		if (pool->pool_type == RDS_IB_MR_8K_POOL)
  			rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_wait);
  		else
  			rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_wait);
  
  		rds_ib_flush_mr_pool(pool, 0, &ibmr);
  		if (ibmr)
  			return ibmr;
  	}
  
  	return ibmr;

  }
  
  static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
  {

  	struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker.work);

  	rds_ib_flush_mr_pool(pool, 0, NULL);

  }
  
  void rds_ib_free_mr(void *trans_private, int invalidate)
  {
  	struct rds_ib_mr *ibmr = trans_private;

  	struct rds_ib_mr_pool *pool = ibmr->pool;

  	struct rds_ib_device *rds_ibdev = ibmr->device;

  
  	rdsdebug("RDS/IB: free_mr nents %u
  ", ibmr->sg_len);
  
  	/* Return it to the pool's free list */

  	if (rds_ibdev->use_fastreg)
  		rds_ib_free_frmr_list(ibmr);
  	else
  		rds_ib_free_fmr_list(ibmr);

  
  	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);

  
  	if (invalidate) {
  		if (likely(!in_interrupt())) {

  			rds_ib_flush_mr_pool(pool, 0, NULL);

  		} else {
  			/* We get here if the user created a MR marked

  			 * as use_once and invalidate at the same time.
  			 */

  			queue_delayed_work(rds_ib_mr_wq,

  					   &pool->flush_worker, 10);

  		}
  	}

  
  	rds_ib_dev_put(rds_ibdev);

  }
  
  void rds_ib_flush_mrs(void)
  {
  	struct rds_ib_device *rds_ibdev;

  	down_read(&rds_ib_devices_lock);

  	list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {

  		if (rds_ibdev->mr_8k_pool)
  			rds_ib_flush_mr_pool(rds_ibdev->mr_8k_pool, 0, NULL);

  		if (rds_ibdev->mr_1m_pool)
  			rds_ib_flush_mr_pool(rds_ibdev->mr_1m_pool, 0, NULL);

  	}

  	up_read(&rds_ib_devices_lock);

  }
  
  void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
  		    struct rds_sock *rs, u32 *key_ret)
  {
  	struct rds_ib_device *rds_ibdev;
  	struct rds_ib_mr *ibmr = NULL;

  	struct rds_ib_connection *ic = rs->rs_conn->c_transport_data;

  	int ret;
  
  	rds_ibdev = rds_ib_get_device(rs->rs_bound_addr);
  	if (!rds_ibdev) {
  		ret = -ENODEV;
  		goto out;
  	}

  	if (!rds_ibdev->mr_8k_pool || !rds_ibdev->mr_1m_pool) {

  		ret = -ENODEV;
  		goto out;
  	}

  	if (rds_ibdev->use_fastreg)
  		ibmr = rds_ib_reg_frmr(rds_ibdev, ic, sg, nents, key_ret);
  	else
  		ibmr = rds_ib_reg_fmr(rds_ibdev, sg, nents, key_ret);

  	if (ibmr)
  		rds_ibdev = NULL;

  
   out:

  	if (!ibmr)
  		pr_warn("RDS/IB: rds_ib_get_mr failed (errno=%d)
  ", ret);

  	if (rds_ibdev)
  		rds_ib_dev_put(rds_ibdev);

  	return ibmr;
  }

  void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
  {
  	cancel_delayed_work_sync(&pool->flush_worker);
  	rds_ib_flush_mr_pool(pool, 1, NULL);
  	WARN_ON(atomic_read(&pool->item_count));
  	WARN_ON(atomic_read(&pool->free_pinned));
  	kfree(pool);
  }
  
  struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev,
  					     int pool_type)
  {
  	struct rds_ib_mr_pool *pool;
  
  	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
  	if (!pool)
  		return ERR_PTR(-ENOMEM);
  
  	pool->pool_type = pool_type;
  	init_llist_head(&pool->free_list);
  	init_llist_head(&pool->drop_list);
  	init_llist_head(&pool->clean_list);
  	mutex_init(&pool->flush_lock);
  	init_waitqueue_head(&pool->flush_wait);
  	INIT_DELAYED_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
  
  	if (pool_type == RDS_IB_MR_1M_POOL) {
  		/* +1 allows for unaligned MRs */
  		pool->fmr_attr.max_pages = RDS_MR_1M_MSG_SIZE + 1;
  		pool->max_items = RDS_MR_1M_POOL_SIZE;
  	} else {
  		/* pool_type == RDS_IB_MR_8K_POOL */
  		pool->fmr_attr.max_pages = RDS_MR_8K_MSG_SIZE + 1;
  		pool->max_items = RDS_MR_8K_POOL_SIZE;
  	}
  
  	pool->max_free_pinned = pool->max_items * pool->fmr_attr.max_pages / 4;
  	pool->fmr_attr.max_maps = rds_ibdev->fmr_max_remaps;
  	pool->fmr_attr.page_shift = PAGE_SHIFT;
  	pool->max_items_soft = rds_ibdev->max_mrs * 3 / 4;

  	pool->use_fastreg = rds_ibdev->use_fastreg;

  
  	return pool;
  }
  
  int rds_ib_mr_init(void)
  {

  	rds_ib_mr_wq = alloc_workqueue("rds_mr_flushd", WQ_MEM_RECLAIM, 0);

  	if (!rds_ib_mr_wq)
  		return -ENOMEM;
  	return 0;
  }
  
  /* By the time this is called all the IB devices should have been torn down and
   * had their pools freed.  As each pool is freed its work struct is waited on,
   * so the pool flushing work queue should be idle by the time we get here.
   */
  void rds_ib_mr_exit(void)
  {
  	destroy_workqueue(rds_ib_mr_wq);
  }