drm_hashtab.c

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/**************************************************************************
 *
 * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND. USA.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * 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 NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
 *
 *
 **************************************************************************/
/*
 * Simple open hash tab implementation.
 *
 * Authors:
 * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
 */

#include <drm/drmP.h>
#include <drm/drm_hashtab.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/export.h>

int drm_ht_create(struct drm_open_hash *ht, unsigned int order)
{
    unsigned int size = 1 << order;

    ht->order = order;
    ht->table = NULL;
    if (size <= PAGE_SIZE / sizeof(*ht->table))
        ht->table = kcalloc(size, sizeof(*ht->table), GFP_KERNEL);
    else
        ht->table = vzalloc(size*sizeof(*ht->table));
    if (!ht->table) {
        DRM_ERROR("Out of memory for hash table\n");
        return -ENOMEM;
    }
    return 0;
}
EXPORT_SYMBOL(drm_ht_create);

void drm_ht_verbose_list(struct drm_open_hash *ht, unsigned long key)
{
    struct drm_hash_item *entry;
    struct hlist_head *h_list;
    struct hlist_node *list;
    unsigned int hashed_key;
    int count = 0;

    hashed_key = hash_long(key, ht->order);
    DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
    h_list = &ht->table[hashed_key];
    hlist_for_each(list, h_list) {
        entry = hlist_entry(list, struct drm_hash_item, head);
        DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
    }
}

static struct hlist_node *drm_ht_find_key(struct drm_open_hash *ht,
                      unsigned long key)
{
    struct drm_hash_item *entry;
    struct hlist_head *h_list;
    struct hlist_node *list;
    unsigned int hashed_key;

    hashed_key = hash_long(key, ht->order);
    h_list = &ht->table[hashed_key];
    hlist_for_each(list, h_list) {
        entry = hlist_entry(list, struct drm_hash_item, head);
        if (entry->key == key)
            return list;
        if (entry->key > key)
            break;
    }
    return NULL;
}


int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
    struct drm_hash_item *entry;
    struct hlist_head *h_list;
    struct hlist_node *list, *parent;
    unsigned int hashed_key;
    unsigned long key = item->key;

    hashed_key = hash_long(key, ht->order);
    h_list = &ht->table[hashed_key];
    parent = NULL;
    hlist_for_each(list, h_list) {
        entry = hlist_entry(list, struct drm_hash_item, head);
        if (entry->key == key)
            return -EINVAL;
        if (entry->key > key)
            break;
        parent = list;
    }
    if (parent) {
        hlist_add_after(parent, &item->head);
    } else {
        hlist_add_head(&item->head, h_list);
    }
    return 0;
}
EXPORT_SYMBOL(drm_ht_insert_item);

/*
 * Just insert an item and return any "bits" bit key that hasn't been
 * used before.
 */
int drm_ht_just_insert_please(struct drm_open_hash *ht, struct drm_hash_item *item,
                  unsigned long seed, int bits, int shift,
                  unsigned long add)
{
    int ret;
    unsigned long mask = (1 << bits) - 1;
    unsigned long first, unshifted_key;

    unshifted_key = hash_long(seed, bits);
    first = unshifted_key;
    do {
        item->key = (unshifted_key << shift) + add;
        ret = drm_ht_insert_item(ht, item);
        if (ret)
            unshifted_key = (unshifted_key + 1) & mask;
    } while(ret && (unshifted_key != first));

    if (ret) {
        DRM_ERROR("Available key bit space exhausted\n");
        return -EINVAL;
    }
    return 0;
}
EXPORT_SYMBOL(drm_ht_just_insert_please);

int drm_ht_find_item(struct drm_open_hash *ht, unsigned long key,
             struct drm_hash_item **item)
{
    struct hlist_node *list;

    list = drm_ht_find_key(ht, key);
    if (!list)
        return -EINVAL;

    *item = hlist_entry(list, struct drm_hash_item, head);
    return 0;
}
EXPORT_SYMBOL(drm_ht_find_item);

int drm_ht_remove_key(struct drm_open_hash *ht, unsigned long key)
{
    struct hlist_node *list;

    list = drm_ht_find_key(ht, key);
    if (list) {
        hlist_del_init(list);
        return 0;
    }
    return -EINVAL;
}

int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
    hlist_del_init(&item->head);
    return 0;
}
EXPORT_SYMBOL(drm_ht_remove_item);

void drm_ht_remove(struct drm_open_hash *ht)
{
    if (ht->table) {
        if ((PAGE_SIZE / sizeof(*ht->table)) >> ht->order)
            kfree(ht->table);
        else
            vfree(ht->table);
        ht->table = NULL;
    }
}
EXPORT_SYMBOL(drm_ht_remove);