blob: 9a72f7d918fa251bd7b21720ba964af5c1cdc341 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/mempool.c
3 *
4 * memory buffer pool support. Such pools are mostly used
5 * for guaranteed, deadlock-free memory allocations during
6 * extreme VM load.
7 *
8 * started by Ingo Molnar, Copyright (C) 2001
9 */
10
11#include <linux/mm.h>
12#include <linux/slab.h>
13#include <linux/module.h>
14#include <linux/mempool.h>
15#include <linux/blkdev.h>
16#include <linux/writeback.h>
17
18static void add_element(mempool_t *pool, void *element)
19{
20 BUG_ON(pool->curr_nr >= pool->min_nr);
21 pool->elements[pool->curr_nr++] = element;
22}
23
24static void *remove_element(mempool_t *pool)
25{
26 BUG_ON(pool->curr_nr <= 0);
27 return pool->elements[--pool->curr_nr];
28}
29
30static void free_pool(mempool_t *pool)
31{
32 while (pool->curr_nr) {
33 void *element = remove_element(pool);
34 pool->free(element, pool->pool_data);
35 }
36 kfree(pool->elements);
37 kfree(pool);
38}
39
40/**
41 * mempool_create - create a memory pool
42 * @min_nr: the minimum number of elements guaranteed to be
43 * allocated for this pool.
44 * @alloc_fn: user-defined element-allocation function.
45 * @free_fn: user-defined element-freeing function.
46 * @pool_data: optional private data available to the user-defined functions.
47 *
48 * this function creates and allocates a guaranteed size, preallocated
49 * memory pool. The pool can be used from the mempool_alloc and mempool_free
50 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
51 * functions might sleep - as long as the mempool_alloc function is not called
52 * from IRQ contexts.
53 */
Christoph Lameter19460892005-06-23 00:08:19 -070054mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 mempool_free_t *free_fn, void *pool_data)
56{
Christoph Lameter19460892005-06-23 00:08:19 -070057 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);
58}
59EXPORT_SYMBOL(mempool_create);
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Christoph Lameter19460892005-06-23 00:08:19 -070061mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
62 mempool_free_t *free_fn, void *pool_data, int node_id)
63{
64 mempool_t *pool;
65 pool = kmalloc_node(sizeof(*pool), GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 if (!pool)
67 return NULL;
68 memset(pool, 0, sizeof(*pool));
Christoph Lameter19460892005-06-23 00:08:19 -070069 pool->elements = kmalloc_node(min_nr * sizeof(void *),
70 GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 if (!pool->elements) {
72 kfree(pool);
73 return NULL;
74 }
75 spin_lock_init(&pool->lock);
76 pool->min_nr = min_nr;
77 pool->pool_data = pool_data;
78 init_waitqueue_head(&pool->wait);
79 pool->alloc = alloc_fn;
80 pool->free = free_fn;
81
82 /*
83 * First pre-allocate the guaranteed number of buffers.
84 */
85 while (pool->curr_nr < pool->min_nr) {
86 void *element;
87
88 element = pool->alloc(GFP_KERNEL, pool->pool_data);
89 if (unlikely(!element)) {
90 free_pool(pool);
91 return NULL;
92 }
93 add_element(pool, element);
94 }
95 return pool;
96}
Christoph Lameter19460892005-06-23 00:08:19 -070097EXPORT_SYMBOL(mempool_create_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
99/**
100 * mempool_resize - resize an existing memory pool
101 * @pool: pointer to the memory pool which was allocated via
102 * mempool_create().
103 * @new_min_nr: the new minimum number of elements guaranteed to be
104 * allocated for this pool.
105 * @gfp_mask: the usual allocation bitmask.
106 *
107 * This function shrinks/grows the pool. In the case of growing,
108 * it cannot be guaranteed that the pool will be grown to the new
109 * size immediately, but new mempool_free() calls will refill it.
110 *
111 * Note, the caller must guarantee that no mempool_destroy is called
112 * while this function is running. mempool_alloc() & mempool_free()
113 * might be called (eg. from IRQ contexts) while this function executes.
114 */
115int mempool_resize(mempool_t *pool, int new_min_nr, unsigned int __nocast gfp_mask)
116{
117 void *element;
118 void **new_elements;
119 unsigned long flags;
120
121 BUG_ON(new_min_nr <= 0);
122
123 spin_lock_irqsave(&pool->lock, flags);
124 if (new_min_nr <= pool->min_nr) {
125 while (new_min_nr < pool->curr_nr) {
126 element = remove_element(pool);
127 spin_unlock_irqrestore(&pool->lock, flags);
128 pool->free(element, pool->pool_data);
129 spin_lock_irqsave(&pool->lock, flags);
130 }
131 pool->min_nr = new_min_nr;
132 goto out_unlock;
133 }
134 spin_unlock_irqrestore(&pool->lock, flags);
135
136 /* Grow the pool */
137 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
138 if (!new_elements)
139 return -ENOMEM;
140
141 spin_lock_irqsave(&pool->lock, flags);
142 if (unlikely(new_min_nr <= pool->min_nr)) {
143 /* Raced, other resize will do our work */
144 spin_unlock_irqrestore(&pool->lock, flags);
145 kfree(new_elements);
146 goto out;
147 }
148 memcpy(new_elements, pool->elements,
149 pool->curr_nr * sizeof(*new_elements));
150 kfree(pool->elements);
151 pool->elements = new_elements;
152 pool->min_nr = new_min_nr;
153
154 while (pool->curr_nr < pool->min_nr) {
155 spin_unlock_irqrestore(&pool->lock, flags);
156 element = pool->alloc(gfp_mask, pool->pool_data);
157 if (!element)
158 goto out;
159 spin_lock_irqsave(&pool->lock, flags);
160 if (pool->curr_nr < pool->min_nr) {
161 add_element(pool, element);
162 } else {
163 spin_unlock_irqrestore(&pool->lock, flags);
164 pool->free(element, pool->pool_data); /* Raced */
165 goto out;
166 }
167 }
168out_unlock:
169 spin_unlock_irqrestore(&pool->lock, flags);
170out:
171 return 0;
172}
173EXPORT_SYMBOL(mempool_resize);
174
175/**
176 * mempool_destroy - deallocate a memory pool
177 * @pool: pointer to the memory pool which was allocated via
178 * mempool_create().
179 *
180 * this function only sleeps if the free_fn() function sleeps. The caller
181 * has to guarantee that all elements have been returned to the pool (ie:
182 * freed) prior to calling mempool_destroy().
183 */
184void mempool_destroy(mempool_t *pool)
185{
186 if (pool->curr_nr != pool->min_nr)
187 BUG(); /* There were outstanding elements */
188 free_pool(pool);
189}
190EXPORT_SYMBOL(mempool_destroy);
191
192/**
193 * mempool_alloc - allocate an element from a specific memory pool
194 * @pool: pointer to the memory pool which was allocated via
195 * mempool_create().
196 * @gfp_mask: the usual allocation bitmask.
197 *
198 * this function only sleeps if the alloc_fn function sleeps or
199 * returns NULL. Note that due to preallocation, this function
200 * *never* fails when called from process contexts. (it might
201 * fail if called from an IRQ context.)
202 */
203void * mempool_alloc(mempool_t *pool, unsigned int __nocast gfp_mask)
204{
205 void *element;
206 unsigned long flags;
Benjamin LaHaise01890a42005-06-23 00:10:01 -0700207 wait_queue_t wait;
Nick Piggin20a77772005-05-01 08:58:37 -0700208 int gfp_temp;
209
210 might_sleep_if(gfp_mask & __GFP_WAIT);
Nick Pigginb84a35b2005-05-01 08:58:36 -0700211
212 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
213 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
214 gfp_mask |= __GFP_NOWARN; /* failures are OK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
Nick Piggin20a77772005-05-01 08:58:37 -0700216 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
217
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218repeat_alloc:
Nick Piggin20a77772005-05-01 08:58:37 -0700219
220 element = pool->alloc(gfp_temp, pool->pool_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 if (likely(element != NULL))
222 return element;
223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 spin_lock_irqsave(&pool->lock, flags);
225 if (likely(pool->curr_nr)) {
226 element = remove_element(pool);
227 spin_unlock_irqrestore(&pool->lock, flags);
228 return element;
229 }
230 spin_unlock_irqrestore(&pool->lock, flags);
231
232 /* We must not sleep in the GFP_ATOMIC case */
233 if (!(gfp_mask & __GFP_WAIT))
234 return NULL;
235
Nick Piggin20a77772005-05-01 08:58:37 -0700236 /* Now start performing page reclaim */
237 gfp_temp = gfp_mask;
Benjamin LaHaise01890a42005-06-23 00:10:01 -0700238 init_wait(&wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700240 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 if (!pool->curr_nr)
242 io_schedule();
243 finish_wait(&pool->wait, &wait);
244
245 goto repeat_alloc;
246}
247EXPORT_SYMBOL(mempool_alloc);
248
249/**
250 * mempool_free - return an element to the pool.
251 * @element: pool element pointer.
252 * @pool: pointer to the memory pool which was allocated via
253 * mempool_create().
254 *
255 * this function only sleeps if the free_fn() function sleeps.
256 */
257void mempool_free(void *element, mempool_t *pool)
258{
259 unsigned long flags;
260
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700261 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 if (pool->curr_nr < pool->min_nr) {
263 spin_lock_irqsave(&pool->lock, flags);
264 if (pool->curr_nr < pool->min_nr) {
265 add_element(pool, element);
266 spin_unlock_irqrestore(&pool->lock, flags);
267 wake_up(&pool->wait);
268 return;
269 }
270 spin_unlock_irqrestore(&pool->lock, flags);
271 }
272 pool->free(element, pool->pool_data);
273}
274EXPORT_SYMBOL(mempool_free);
275
276/*
277 * A commonly used alloc and free fn.
278 */
279void *mempool_alloc_slab(unsigned int __nocast gfp_mask, void *pool_data)
280{
281 kmem_cache_t *mem = (kmem_cache_t *) pool_data;
282 return kmem_cache_alloc(mem, gfp_mask);
283}
284EXPORT_SYMBOL(mempool_alloc_slab);
285
286void mempool_free_slab(void *element, void *pool_data)
287{
288 kmem_cache_t *mem = (kmem_cache_t *) pool_data;
289 kmem_cache_free(mem, element);
290}
291EXPORT_SYMBOL(mempool_free_slab);