drivers/staging/android/ion/ion_page_pool.c

   1 /*
   2  * drivers/staging/android/ion/ion_mem_pool.c
   3  *
   4  * Copyright (C) 2011 Google, Inc.
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  */
  16
  17 #include <linux/debugfs.h>
  18 #include <linux/dma-mapping.h>
  19 #include <linux/err.h>
  20 #include <linux/fs.h>
  21 #include <linux/list.h>
  22 #include <linux/init.h>
  23 #include <linux/slab.h>
  24 #include <linux/swap.h>
  25 #include "ion_priv.h"
  26
  27 static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
  28 {
  29         struct page *page = alloc_pages(pool->gfp_mask, pool->order);
  30
  31         if (!page)
  32                 return NULL;
  33         return page;
  34 }
  35
  36 static void ion_page_pool_free_pages(struct ion_page_pool *pool,
  37                                      struct page *page)
  38 {
  39         __free_pages(page, pool->order);
  40 }
  41
  42 static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
  43 {
  44         mutex_lock(&pool->mutex);
  45         if (PageHighMem(page)) {
  46                 list_add_tail(&page->lru, &pool->high_items);
  47                 pool->high_count++;
  48         } else {
  49                 list_add_tail(&page->lru, &pool->low_items);
  50                 pool->low_count++;
  51         }
  52         mutex_unlock(&pool->mutex);
  53         return 0;
  54 }
  55
  56 static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)
  57 {
  58         struct page *page;
  59
  60         if (high) {
  61                 BUG_ON(!pool->high_count);
  62                 page = list_first_entry(&pool->high_items, struct page, lru);
  63                 pool->high_count--;
  64         } else {
  65                 BUG_ON(!pool->low_count);
  66                 page = list_first_entry(&pool->low_items, struct page, lru);
  67                 pool->low_count--;
  68         }
  69
  70         list_del(&page->lru);
  71         return page;
  72 }
  73
  74 struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
  75 {
  76         struct page *page = NULL;
  77
  78         BUG_ON(!pool);
  79
  80         mutex_lock(&pool->mutex);
  81         if (pool->high_count)
  82                 page = ion_page_pool_remove(pool, true);
  83         else if (pool->low_count)
  84                 page = ion_page_pool_remove(pool, false);
  85         mutex_unlock(&pool->mutex);
  86
  87         if (!page)
  88                 page = ion_page_pool_alloc_pages(pool);
  89
  90         return page;
  91 }
  92
  93 void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
  94 {
  95         int ret;
  96
  97         BUG_ON(pool->order != compound_order(page));
  98
  99         ret = ion_page_pool_add(pool, page);
 100         if (ret)
 101                 ion_page_pool_free_pages(pool, page);
 102 }
 103
 104 static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
 105 {
 106         int count = pool->low_count;
 107
 108         if (high)
 109                 count += pool->high_count;
 110
 111         return count << pool->order;
 112 }
 113
 114 int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 115                          int nr_to_scan)
 116 {
 117         int freed = 0;
 118         bool high;
 119
 120         if (current_is_kswapd())
 121                 high = true;
 122         else
 123                 high = !!(gfp_mask & __GFP_HIGHMEM);
 124
 125         if (nr_to_scan == 0)
 126                 return ion_page_pool_total(pool, high);
 127
 128         while (freed < nr_to_scan) {
 129                 struct page *page;
 130
 131                 mutex_lock(&pool->mutex);
 132                 if (pool->low_count) {
 133                         page = ion_page_pool_remove(pool, false);
 134                 } else if (high && pool->high_count) {
 135                         page = ion_page_pool_remove(pool, true);
 136                 } else {
 137                         mutex_unlock(&pool->mutex);
 138                         break;
 139                 }
 140                 mutex_unlock(&pool->mutex);
 141                 ion_page_pool_free_pages(pool, page);
 142                 freed += (1 << pool->order);
 143         }
 144
 145         return freed;
 146 }
 147
 148 struct ion_page_pool *ion_page_pool_create(gfp_t gfp_mask, unsigned int order,
 149                                            bool cached)
 150 {
 151         struct ion_page_pool *pool = kmalloc(sizeof(*pool), GFP_KERNEL);
 152
 153         if (!pool)
 154                 return NULL;
 155         pool->high_count = 0;
 156         pool->low_count = 0;
 157         INIT_LIST_HEAD(&pool->low_items);
 158         INIT_LIST_HEAD(&pool->high_items);
 159         pool->gfp_mask = gfp_mask | __GFP_COMP;
 160         pool->order = order;
 161         mutex_init(&pool->mutex);
 162         plist_node_init(&pool->list, order);
 163         if (cached)
 164                 pool->cached = true;
 165
 166         return pool;
 167 }
 168
 169 void ion_page_pool_destroy(struct ion_page_pool *pool)
 170 {
 171         kfree(pool);
 172 }
 173
 174 static int __init ion_page_pool_init(void)
 175 {
 176         return 0;
 177 }
 178 device_initcall(ion_page_pool_init);