ion_page_pool.c revision efee5a0c62d827c0eca7044c2d14dd3324b325aa 
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/dma-mapping.h>
18#include <linux/err.h>
19#include <linux/list.h>
20#include <linux/slab.h>
21#include <linux/shrinker.h>
22#include "ion_priv.h"
23
24struct ion_page_pool_item {
25	struct page *page;
26	struct list_head list;
27};
28
29static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
30{
31	struct page *page = alloc_pages(pool->gfp_mask, pool->order);
32
33	if (!page)
34		return NULL;
35	/* this is only being used to flush the page for dma,
36	   this api is not really suitable for calling from a driver
37	   but no better way to flush a page for dma exist at this time */
38	__dma_page_cpu_to_dev(page, 0, PAGE_SIZE << pool->order,
39			      DMA_BIDIRECTIONAL);
40	return page;
41}
42
43static void ion_page_pool_free_pages(struct ion_page_pool *pool,
44				     struct page *page)
45{
46	__free_pages(page, pool->order);
47}
48
49static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
50{
51	struct ion_page_pool_item *item;
52
53	item = kmalloc(sizeof(struct ion_page_pool_item), GFP_KERNEL);
54	if (!item)
55		return -ENOMEM;
56
57	mutex_lock(&pool->mutex);
58	item->page = page;
59	if (PageHighMem(page)) {
60		list_add_tail(&item->list, &pool->high_items);
61		pool->high_count++;
62	} else {
63		list_add_tail(&item->list, &pool->low_items);
64		pool->low_count++;
65	}
66	mutex_unlock(&pool->mutex);
67	return 0;
68}
69
70static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)
71{
72	struct ion_page_pool_item *item;
73	struct page *page;
74
75	if (high) {
76		BUG_ON(!pool->high_count);
77		item = list_first_entry(&pool->high_items,
78					struct ion_page_pool_item, list);
79		pool->high_count--;
80	} else {
81		BUG_ON(!pool->low_count);
82		item = list_first_entry(&pool->low_items,
83					struct ion_page_pool_item, list);
84		pool->low_count--;
85	}
86
87	list_del(&item->list);
88	page = item->page;
89	kfree(item);
90	return page;
91}
92
93void *ion_page_pool_alloc(struct ion_page_pool *pool)
94{
95	struct page *page = NULL;
96
97	BUG_ON(!pool);
98
99	mutex_lock(&pool->mutex);
100	if (pool->high_count)
101		page = ion_page_pool_remove(pool, true);
102	else if (pool->low_count)
103		page = ion_page_pool_remove(pool, false);
104	mutex_unlock(&pool->mutex);
105
106	if (!page)
107		page = ion_page_pool_alloc_pages(pool);
108
109	return page;
110}
111
112void ion_page_pool_free(struct ion_page_pool *pool, struct page* page)
113{
114	int ret;
115
116	ret = ion_page_pool_add(pool, page);
117	if (ret)
118		ion_page_pool_free_pages(pool, page);
119}
120
121static int ion_page_pool_shrink(struct shrinker *shrinker,
122				 struct shrink_control *sc)
123{
124	struct ion_page_pool *pool = container_of(shrinker,
125						 struct ion_page_pool,
126						 shrinker);
127	int nr_freed = 0;
128	int i;
129	bool high;
130
131	if (sc->gfp_mask & __GFP_HIGHMEM)
132		high = true;
133
134	if (sc->nr_to_scan == 0)
135		return high ? (pool->high_count + pool->low_count) *
136			(1 << pool->order) :
137			pool->low_count * (1 << pool->order);
138
139	for (i = 0; i < sc->nr_to_scan; i++) {
140		struct page *page;
141
142		mutex_lock(&pool->mutex);
143		if (high && pool->high_count) {
144			page = ion_page_pool_remove(pool, true);
145		} else if (pool->low_count) {
146			page = ion_page_pool_remove(pool, false);
147		} else {
148			mutex_unlock(&pool->mutex);
149			break;
150		}
151		mutex_unlock(&pool->mutex);
152		ion_page_pool_free_pages(pool, page);
153		nr_freed += (1 << pool->order);
154	}
155	pr_info("%s: shrunk page_pool of order %d by %d pages\n", __func__,
156		pool->order, nr_freed);
157
158	return high ? (pool->high_count + pool->low_count) *
159		(1 << pool->order) :
160		pool->low_count * (1 << pool->order);
161}
162
163struct ion_page_pool *ion_page_pool_create(gfp_t gfp_mask, unsigned int order)
164{
165	struct ion_page_pool *pool = kmalloc(sizeof(struct ion_page_pool),
166					     GFP_KERNEL);
167	if (!pool)
168		return NULL;
169	pool->high_count = 0;
170	pool->low_count = 0;
171	INIT_LIST_HEAD(&pool->low_items);
172	INIT_LIST_HEAD(&pool->high_items);
173	pool->shrinker.shrink = ion_page_pool_shrink;
174	pool->shrinker.seeks = DEFAULT_SEEKS * 16;
175	pool->shrinker.batch = 0;
176	register_shrinker(&pool->shrinker);
177	pool->gfp_mask = gfp_mask;
178	pool->order = order;
179	mutex_init(&pool->mutex);
180
181	return pool;
182}
183
184void ion_page_pool_destroy(struct ion_page_pool *pool)
185{
186	unregister_shrinker(&pool->shrinker);
187	kfree(pool);
188}
189
190