text: /*
   * Copyright (c) 2004 Topspin Communications.  All rights reserved.
   * Copyright (c) 2005 Sun Microsystems, Inc. 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/errno.h>
  #include <linux/spinlock.h>
  #include <linux/export.h>
  #include <linux/slab.h>
  #include <linux/jhash.h>
  #include <linux/kthread.h>
  
  #include <rdma/ib_fmr_pool.h>
  
  #include "core_priv.h"
  
  #define PFX "fmr_pool: "
  
  enum {
  	IB_FMR_MAX_REMAPS = 32,
  
  	IB_FMR_HASH_BITS  = 8,
  	IB_FMR_HASH_SIZE  = 1 << IB_FMR_HASH_BITS,
  	IB_FMR_HASH_MASK  = IB_FMR_HASH_SIZE - 1
  };
  
  /*
   * If an FMR is not in use, then the list member will point to either
   * its pool's free_list (if the FMR can be mapped again; that is,
   * remap_count < pool->max_remaps) or its pool's dirty_list (if the
   * FMR needs to be unmapped before being remapped).  In either of
   * these cases it is a bug if the ref_count is not 0.  In other words,
   * if ref_count is > 0, then the list member must not be linked into
   * either free_list or dirty_list.
   *
   * The cache_node member is used to link the FMR into a cache bucket
   * (if caching is enabled).  This is independent of the reference
   * count of the FMR.  When a valid FMR is released, its ref_count is
   * decremented, and if ref_count reaches 0, the FMR is placed in
   * either free_list or dirty_list as appropriate.  However, it is not
   * removed from the cache and may be "revived" if a call to
   * ib_fmr_register_physical() occurs before the FMR is remapped.  In
   * this case we just increment the ref_count and remove the FMR from
   * free_list/dirty_list.
   *
   * Before we remap an FMR from free_list, we remove it from the cache
   * (to prevent another user from obtaining a stale FMR).  When an FMR
   * is released, we add it to the tail of the free list, so that our
   * cache eviction policy is "least recently used."
   *
   * All manipulation of ref_count, list and cache_node is protected by
   * pool_lock to maintain consistency.
   */
  
  struct ib_fmr_pool {
  	spinlock_t                pool_lock;
  
  	int                       pool_size;
  	int                       max_pages;
  	int			  max_remaps;
  	int                       dirty_watermark;
  	int                       dirty_len;
  	struct list_head          free_list;
  	struct list_head          dirty_list;
  	struct hlist_head        *cache_bucket;
  
  	void                     (*flush_function)(struct ib_fmr_pool *pool,
  						   void *              arg);
  	void                     *flush_arg;
  
  	struct task_struct       *thread;
  
  	atomic_t                  req_ser;
  	atomic_t                  flush_ser;
  
  	wait_queue_head_t         force_wait;
  };
  
  static inline u32 ib_fmr_hash(u64 first_page)
  {
  	return jhash_2words((u32) first_page, (u32) (first_page >> 32), 0) &
  		(IB_FMR_HASH_SIZE - 1);
  }
  
  /* Caller must hold pool_lock */
  static inline struct ib_pool_fmr *ib_fmr_cache_lookup(struct ib_fmr_pool *pool,
  						      u64 *page_list,
  						      int  page_list_len,
  						      u64  io_virtual_address)
  {
  	struct hlist_head *bucket;
  	struct ib_pool_fmr *fmr;
  
  	if (!pool->cache_bucket)
  		return NULL;
  
  	bucket = pool->cache_bucket + ib_fmr_hash(*page_list);
  
  	hlist_for_each_entry(fmr, bucket, cache_node)
  		if (io_virtual_address == fmr->io_virtual_address &&
  		    page_list_len      == fmr->page_list_len      &&
  		    !memcmp(page_list, fmr->page_list,
  			    page_list_len * sizeof *page_list))
  			return fmr;
  
  	return NULL;
  }
  
  static void ib_fmr_batch_release(struct ib_fmr_pool *pool)
  {
  	int                 ret;
  	struct ib_pool_fmr *fmr;
  	LIST_HEAD(unmap_list);
  	LIST_HEAD(fmr_list);
  
  	spin_lock_irq(&pool->pool_lock);
  
  	list_for_each_entry(fmr, &pool->dirty_list, list) {
  		hlist_del_init(&fmr->cache_node);
  		fmr->remap_count = 0;
  		list_add_tail(&fmr->fmr->list, &fmr_list);
  
  #ifdef DEBUG
  		if (fmr->ref_count !=0) {
  			pr_warn(PFX "Unmapping FMR 0x%08x with ref count %d\n",
  				fmr, fmr->ref_count);
  		}
  #endif
  	}
  
  	list_splice_init(&pool->dirty_list, &unmap_list);
  	pool->dirty_len = 0;
  
  	spin_unlock_irq(&pool->pool_lock);
  
  	if (list_empty(&unmap_list)) {
  		return;
  	}
  
  	ret = ib_unmap_fmr(&fmr_list);
  	if (ret)
  		pr_warn(PFX "ib_unmap_fmr returned %d\n", ret);
  
  	spin_lock_irq(&pool->pool_lock);
  	list_splice(&unmap_list, &pool->free_list);
  	spin_unlock_irq(&pool->pool_lock);
  }
  
  static int ib_fmr_cleanup_thread(void *pool_ptr)
  {
  	struct ib_fmr_pool *pool = pool_ptr;
  
  	do {
  		if (atomic_read(&pool->flush_ser) - atomic_read(&pool->req_ser) < 0) {
  			ib_fmr_batch_release(pool);
  
  			atomic_inc(&pool->flush_ser);
  			wake_up_interruptible(&pool->force_wait);
  
  			if (pool->flush_function)
  				pool->flush_function(pool, pool->flush_arg);
  		}
  
  		set_current_state(TASK_INTERRUPTIBLE);
  		if (atomic_read(&pool->flush_ser) - atomic_read(&pool->req_ser) >= 0 &&
  		    !kthread_should_stop())
  			schedule();
  		__set_current_state(TASK_RUNNING);
  	} while (!kthread_should_stop());
  
  	return 0;
  }
  
  /**
   * ib_create_fmr_pool - Create an FMR pool
   * @pd:Protection domain for FMRs
   * @params:FMR pool parameters
   *
   * Create a pool of FMRs.  Return value is pointer to new pool or
   * error code if creation failed.
   */
  struct ib_fmr_pool *ib_create_fmr_pool(struct ib_pd             *pd,
  				       struct ib_fmr_pool_param *params)
  {
  	struct ib_device   *device;
  	struct ib_fmr_pool *pool;
  	int i;
  	int ret;
  	int max_remaps;
  
  	if (!params)
  		return ERR_PTR(-EINVAL);
  
  	device = pd->device;
  	if (!device->alloc_fmr    || !device->dealloc_fmr  ||
  	    !device->map_phys_fmr || !device->unmap_fmr) {
  		pr_info(PFX "Device %s does not support FMRs\n", device->name);
  		return ERR_PTR(-ENOSYS);
  	}
  
  	if (!device->attrs.max_map_per_fmr)
  		max_remaps = IB_FMR_MAX_REMAPS;
  	else
  		max_remaps = device->attrs.max_map_per_fmr;
  
  	pool = kmalloc(sizeof *pool, GFP_KERNEL);
  	if (!pool)
  		return ERR_PTR(-ENOMEM);
  
  	pool->cache_bucket   = NULL;
  	pool->flush_function = params->flush_function;
  	pool->flush_arg      = params->flush_arg;
  
  	INIT_LIST_HEAD(&pool->free_list);
  	INIT_LIST_HEAD(&pool->dirty_list);
  
  	if (params->cache) {
  		pool->cache_bucket =
  			kmalloc(IB_FMR_HASH_SIZE * sizeof *pool->cache_bucket,
  				GFP_KERNEL);
  		if (!pool->cache_bucket) {
  			pr_warn(PFX "Failed to allocate cache in pool\n");
  			ret = -ENOMEM;
  			goto out_free_pool;
  		}
  
  		for (i = 0; i < IB_FMR_HASH_SIZE; ++i)
  			INIT_HLIST_HEAD(pool->cache_bucket + i);
  	}
  
  	pool->pool_size       = 0;
  	pool->max_pages       = params->max_pages_per_fmr;
  	pool->max_remaps      = max_remaps;
  	pool->dirty_watermark = params->dirty_watermark;
  	pool->dirty_len       = 0;
  	spin_lock_init(&pool->pool_lock);
  	atomic_set(&pool->req_ser,   0);
  	atomic_set(&pool->flush_ser, 0);
  	init_waitqueue_head(&pool->force_wait);
  
  	pool->thread = kthread_run(ib_fmr_cleanup_thread,
  				   pool,
  				   "ib_fmr(%s)",
  				   device->name);
  	if (IS_ERR(pool->thread)) {
  		pr_warn(PFX "couldn't start cleanup thread\n");
  		ret = PTR_ERR(pool->thread);
  		goto out_free_pool;
  	}
  
  	{
  		struct ib_pool_fmr *fmr;
  		struct ib_fmr_attr fmr_attr = {
  			.max_pages  = params->max_pages_per_fmr,
  			.max_maps   = pool->max_remaps,
  			.page_shift = params->page_shift
  		};
  		int bytes_per_fmr = sizeof *fmr;
  
  		if (pool->cache_bucket)
  			bytes_per_fmr += params->max_pages_per_fmr * sizeof (u64);
  
  		for (i = 0; i < params->pool_size; ++i) {
  			fmr = kmalloc(bytes_per_fmr, GFP_KERNEL);
  			if (!fmr)
  				goto out_fail;
  
  			fmr->pool             = pool;
  			fmr->remap_count      = 0;
  			fmr->ref_count        = 0;
  			INIT_HLIST_NODE(&fmr->cache_node);
  
  			fmr->fmr = ib_alloc_fmr(pd, params->access, &fmr_attr);
  			if (IS_ERR(fmr->fmr)) {
  				pr_warn(PFX "fmr_create failed for FMR %d\n",
  					i);
  				kfree(fmr);
  				goto out_fail;
  			}
  
  			list_add_tail(&fmr->list, &pool->free_list);
  			++pool->pool_size;
  		}
  	}
  
  	return pool;
  
   out_free_pool:
  	kfree(pool->cache_bucket);
  	kfree(pool);
  
  	return ERR_PTR(ret);
  
   out_fail:
  	ib_destroy_fmr_pool(pool);
  
  	return ERR_PTR(-ENOMEM);
  }
  EXPORT_SYMBOL(ib_create_fmr_pool);
  
  /**
   * ib_destroy_fmr_pool - Free FMR pool
   * @pool:FMR pool to free
   *
   * Destroy an FMR pool and free all associated resources.
   */
  void ib_destroy_fmr_pool(struct ib_fmr_pool *pool)
  {
  	struct ib_pool_fmr *fmr;
  	struct ib_pool_fmr *tmp;
  	LIST_HEAD(fmr_list);
  	int                 i;
  
  	kthread_stop(pool->thread);
  	ib_fmr_batch_release(pool);
  
  	i = 0;
  	list_for_each_entry_safe(fmr, tmp, &pool->free_list, list) {
  		if (fmr->remap_count) {
  			INIT_LIST_HEAD(&fmr_list);
  			list_add_tail(&fmr->fmr->list, &fmr_list);
  			ib_unmap_fmr(&fmr_list);
  		}
  		ib_dealloc_fmr(fmr->fmr);
  		list_del(&fmr->list);
  		kfree(fmr);
  		++i;
  	}
  
  	if (i < pool->pool_size)
  		pr_warn(PFX "pool still has %d regions registered\n",
  			pool->pool_size - i);
  
  	kfree(pool->cache_bucket);
  	kfree(pool);
  }
  EXPORT_SYMBOL(ib_destroy_fmr_pool);
  
  /**
   * ib_flush_fmr_pool - Invalidate all unmapped FMRs
   * @pool:FMR pool to flush
   *
   * Ensure that all unmapped FMRs are fully invalidated.
   */
  int ib_flush_fmr_pool(struct ib_fmr_pool *pool)
  {
  	int serial;
  	struct ib_pool_fmr *fmr, *next;
  
  	/*
  	 * The free_list holds FMRs that may have been used
  	 * but have not been remapped enough times to be dirty.
  	 * Put them on the dirty list now so that the cleanup
  	 * thread will reap them too.
  	 */
  	spin_lock_irq(&pool->pool_lock);
  	list_for_each_entry_safe(fmr, next, &pool->free_list, list) {
  		if (fmr->remap_count > 0)
  			list_move(&fmr->list, &pool->dirty_list);
  	}
  	spin_unlock_irq(&pool->pool_lock);
  
  	serial = atomic_inc_return(&pool->req_ser);
  	wake_up_process(pool->thread);
  
  	if (wait_event_interruptible(pool->force_wait,
  				     atomic_read(&pool->flush_ser) - serial >= 0))
  		return -EINTR;
  
  	return 0;
  }
  EXPORT_SYMBOL(ib_flush_fmr_pool);
  
  /**
   * ib_fmr_pool_map_phys -
   * @pool:FMR pool to allocate FMR from
   * @page_list:List of pages to map
   * @list_len:Number of pages in @page_list
   * @io_virtual_address:I/O virtual address for new FMR
   *
   * Map an FMR from an FMR pool.
   */
  struct ib_pool_fmr *ib_fmr_pool_map_phys(struct ib_fmr_pool *pool_handle,
  					 u64                *page_list,
  					 int                 list_len,
  					 u64                 io_virtual_address)
  {
  	struct ib_fmr_pool *pool = pool_handle;
  	struct ib_pool_fmr *fmr;
  	unsigned long       flags;
  	int                 result;
  
  	if (list_len < 1 || list_len > pool->max_pages)
  		return ERR_PTR(-EINVAL);
  
  	spin_lock_irqsave(&pool->pool_lock, flags);
  	fmr = ib_fmr_cache_lookup(pool,
  				  page_list,
  				  list_len,
  				  io_virtual_address);
  	if (fmr) {
  		/* found in cache */
  		++fmr->ref_count;
  		if (fmr->ref_count == 1) {
  			list_del(&fmr->list);
  		}
  
  		spin_unlock_irqrestore(&pool->pool_lock, flags);
  
  		return fmr;
  	}
  
  	if (list_empty(&pool->free_list)) {
  		spin_unlock_irqrestore(&pool->pool_lock, flags);
  		return ERR_PTR(-EAGAIN);
  	}
  
  	fmr = list_entry(pool->free_list.next, struct ib_pool_fmr, list);
  	list_del(&fmr->list);
  	hlist_del_init(&fmr->cache_node);
  	spin_unlock_irqrestore(&pool->pool_lock, flags);
  
  	result = ib_map_phys_fmr(fmr->fmr, page_list, list_len,
  				 io_virtual_address);
  
  	if (result) {
  		spin_lock_irqsave(&pool->pool_lock, flags);
  		list_add(&fmr->list, &pool->free_list);
  		spin_unlock_irqrestore(&pool->pool_lock, flags);
  
  		pr_warn(PFX "fmr_map returns %d\n", result);
  
  		return ERR_PTR(result);
  	}
  
  	++fmr->remap_count;
  	fmr->ref_count = 1;
  
  	if (pool->cache_bucket) {
  		fmr->io_virtual_address = io_virtual_address;
  		fmr->page_list_len      = list_len;
  		memcpy(fmr->page_list, page_list, list_len * sizeof(*page_list));
  
  		spin_lock_irqsave(&pool->pool_lock, flags);
  		hlist_add_head(&fmr->cache_node,
  			       pool->cache_bucket + ib_fmr_hash(fmr->page_list[0]));
  		spin_unlock_irqrestore(&pool->pool_lock, flags);
  	}
  
  	return fmr;
  }
  EXPORT_SYMBOL(ib_fmr_pool_map_phys);
  
  /**
   * ib_fmr_pool_unmap - Unmap FMR
   * @fmr:FMR to unmap
   *
   * Unmap an FMR.  The FMR mapping may remain valid until the FMR is
   * reused (or until ib_flush_fmr_pool() is called).
   */
  int ib_fmr_pool_unmap(struct ib_pool_fmr *fmr)
  {
  	struct ib_fmr_pool *pool;
  	unsigned long flags;
  
  	pool = fmr->pool;
  
  	spin_lock_irqsave(&pool->pool_lock, flags);
  
  	--fmr->ref_count;
  	if (!fmr->ref_count) {
  		if (fmr->remap_count < pool->max_remaps) {
  			list_add_tail(&fmr->list, &pool->free_list);
  		} else {
  			list_add_tail(&fmr->list, &pool->dirty_list);
  			if (++pool->dirty_len >= pool->dirty_watermark) {
  				atomic_inc(&pool->req_ser);
  				wake_up_process(pool->thread);
  			}
  		}
  	}
  
  #ifdef DEBUG
  	if (fmr->ref_count < 0)
  		pr_warn(PFX "FMR %p has ref count %d < 0\n",
  			fmr, fmr->ref_count);
  #endif
  
  	spin_unlock_irqrestore(&pool->pool_lock, flags);
  
  	return 0;
  }
  EXPORT_SYMBOL(ib_fmr_pool_unmap);
  