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fmr_pool.c

/*
 * 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.
 *
 * $Id: fmr_pool.c 2730 2005-06-28 16:43:03Z sean.hefty $
 */

#include <linux/errno.h>
#include <linux/spinlock.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;
      struct hlist_node *pos;

      if (!pool->cache_bucket)
            return NULL;

      bucket = pool->cache_bucket + ib_fmr_hash(*page_list);

      hlist_for_each_entry(fmr, pos, 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) {
                  printk(KERN_WARNING PFX "Unmapping FMR 0x%08x with ref count %d\n",
                         fmr, fmr->ref_count);
            }
#endif
      }

      list_splice(&pool->dirty_list, &unmap_list);
      INIT_LIST_HEAD(&pool->dirty_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)
            printk(KERN_WARNING 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 (pool->dirty_len >= pool->dirty_watermark ||
                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 (pool->dirty_len < pool->dirty_watermark &&
                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;
      struct ib_device_attr *attr;
      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) {
            printk(KERN_INFO PFX "Device %s does not support FMRs\n",
                   device->name);
            return ERR_PTR(-ENOSYS);
      }

      attr = kmalloc(sizeof *attr, GFP_KERNEL);
      if (!attr) {
            printk(KERN_WARNING PFX "couldn't allocate device attr struct\n");
            return ERR_PTR(-ENOMEM);
      }

      ret = ib_query_device(device, attr);
      if (ret) {
            printk(KERN_WARNING PFX "couldn't query device: %d\n", ret);
            kfree(attr);
            return ERR_PTR(ret);
      }

      if (!attr->max_map_per_fmr)
            max_remaps = IB_FMR_MAX_REMAPS;
      else
            max_remaps = attr->max_map_per_fmr;

      kfree(attr);

      pool = kmalloc(sizeof *pool, GFP_KERNEL);
      if (!pool) {
            printk(KERN_WARNING PFX "couldn't allocate pool struct\n");
            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) {
                  printk(KERN_WARNING 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)) {
            printk(KERN_WARNING 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
            };

            for (i = 0; i < params->pool_size; ++i) {
                  fmr = kmalloc(sizeof *fmr + params->max_pages_per_fmr * sizeof (u64),
                              GFP_KERNEL);
                  if (!fmr) {
                        printk(KERN_WARNING PFX "failed to allocate fmr "
                               "struct for FMR %d\n", i);
                        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)) {
                        printk(KERN_WARNING 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)
            printk(KERN_WARNING 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 = 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);

            printk(KERN_WARNING 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);
                  ++pool->dirty_len;
                  wake_up_process(pool->thread);
            }
      }

#ifdef DEBUG
      if (fmr->ref_count < 0)
            printk(KERN_WARNING 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);

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