/*
 * 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) {
                        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);