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1/*
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 */
54mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
55 mempool_free_t *free_fn, void *pool_data)
56{
57 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);
58}
59EXPORT_SYMBOL(mempool_create);
60
61mempool_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 | __GFP_ZERO, node_id);
66 if (!pool)
67 return NULL;
68 pool->elements = kmalloc_node(min_nr * sizeof(void *),
69 GFP_KERNEL, node_id);
70 if (!pool->elements) {
71 kfree(pool);
72 return NULL;
73 }
74 spin_lock_init(&pool->lock);
75 pool->min_nr = min_nr;
76 pool->pool_data = pool_data;
77 init_waitqueue_head(&pool->wait);
78 pool->alloc = alloc_fn;
79 pool->free = free_fn;
80
81 /*
82 * First pre-allocate the guaranteed number of buffers.
83 */
84 while (pool->curr_nr < pool->min_nr) {
85 void *element;
86
87 element = pool->alloc(GFP_KERNEL, pool->pool_data);
88 if (unlikely(!element)) {
89 free_pool(pool);
90 return NULL;
91 }
92 add_element(pool, element);
93 }
94 return pool;
95}
96EXPORT_SYMBOL(mempool_create_node);
97
98/**
99 * mempool_resize - resize an existing memory pool
100 * @pool: pointer to the memory pool which was allocated via
101 * mempool_create().
102 * @new_min_nr: the new minimum number of elements guaranteed to be
103 * allocated for this pool.
104 * @gfp_mask: the usual allocation bitmask.
105 *
106 * This function shrinks/grows the pool. In the case of growing,
107 * it cannot be guaranteed that the pool will be grown to the new
108 * size immediately, but new mempool_free() calls will refill it.
109 *
110 * Note, the caller must guarantee that no mempool_destroy is called
111 * while this function is running. mempool_alloc() & mempool_free()
112 * might be called (eg. from IRQ contexts) while this function executes.
113 */
114int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
115{
116 void *element;
117 void **new_elements;
118 unsigned long flags;
119
120 BUG_ON(new_min_nr <= 0);
121
122 spin_lock_irqsave(&pool->lock, flags);
123 if (new_min_nr <= pool->min_nr) {
124 while (new_min_nr < pool->curr_nr) {
125 element = remove_element(pool);
126 spin_unlock_irqrestore(&pool->lock, flags);
127 pool->free(element, pool->pool_data);
128 spin_lock_irqsave(&pool->lock, flags);
129 }
130 pool->min_nr = new_min_nr;
131 goto out_unlock;
132 }
133 spin_unlock_irqrestore(&pool->lock, flags);
134
135 /* Grow the pool */
136 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
137 if (!new_elements)
138 return -ENOMEM;
139
140 spin_lock_irqsave(&pool->lock, flags);
141 if (unlikely(new_min_nr <= pool->min_nr)) {
142 /* Raced, other resize will do our work */
143 spin_unlock_irqrestore(&pool->lock, flags);
144 kfree(new_elements);
145 goto out;
146 }
147 memcpy(new_elements, pool->elements,
148 pool->curr_nr * sizeof(*new_elements));
149 kfree(pool->elements);
150 pool->elements = new_elements;
151 pool->min_nr = new_min_nr;
152
153 while (pool->curr_nr < pool->min_nr) {
154 spin_unlock_irqrestore(&pool->lock, flags);
155 element = pool->alloc(gfp_mask, pool->pool_data);
156 if (!element)
157 goto out;
158 spin_lock_irqsave(&pool->lock, flags);
159 if (pool->curr_nr < pool->min_nr) {
160 add_element(pool, element);
161 } else {
162 spin_unlock_irqrestore(&pool->lock, flags);
163 pool->free(element, pool->pool_data); /* Raced */
164 goto out;
165 }
166 }
167out_unlock:
168 spin_unlock_irqrestore(&pool->lock, flags);
169out:
170 return 0;
171}
172EXPORT_SYMBOL(mempool_resize);
173
174/**
175 * mempool_destroy - deallocate a memory pool
176 * @pool: pointer to the memory pool which was allocated via
177 * mempool_create().
178 *
179 * this function only sleeps if the free_fn() function sleeps. The caller
180 * has to guarantee that all elements have been returned to the pool (ie:
181 * freed) prior to calling mempool_destroy().
182 */
183void mempool_destroy(mempool_t *pool)
184{
185 /* Check for outstanding elements */
186 BUG_ON(pool->curr_nr != pool->min_nr);
187 free_pool(pool);
188}
189EXPORT_SYMBOL(mempool_destroy);
190
191/**
192 * mempool_alloc - allocate an element from a specific memory pool
193 * @pool: pointer to the memory pool which was allocated via
194 * mempool_create().
195 * @gfp_mask: the usual allocation bitmask.
196 *
197 * this function only sleeps if the alloc_fn() function sleeps or
198 * returns NULL. Note that due to preallocation, this function
199 * *never* fails when called from process contexts. (it might
200 * fail if called from an IRQ context.)
201 */
202void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
203{
204 void *element;
205 unsigned long flags;
206 wait_queue_t wait;
207 gfp_t gfp_temp;
208
209 might_sleep_if(gfp_mask & __GFP_WAIT);
210
211 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
212 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
213 gfp_mask |= __GFP_NOWARN; /* failures are OK */
214
215 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
216
217repeat_alloc:
218
219 element = pool->alloc(gfp_temp, pool->pool_data);
220 if (likely(element != NULL))
221 return element;
222
223 spin_lock_irqsave(&pool->lock, flags);
224 if (likely(pool->curr_nr)) {
225 element = remove_element(pool);
226 spin_unlock_irqrestore(&pool->lock, flags);
227 return element;
228 }
229 spin_unlock_irqrestore(&pool->lock, flags);
230
231 /* We must not sleep in the GFP_ATOMIC case */
232 if (!(gfp_mask & __GFP_WAIT))
233 return NULL;
234
235 /* Now start performing page reclaim */
236 gfp_temp = gfp_mask;
237 init_wait(&wait);
238 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
239 smp_mb();
240 if (!pool->curr_nr) {
241 /*
242 * FIXME: this should be io_schedule(). The timeout is there
243 * as a workaround for some DM problems in 2.6.18.
244 */
245 io_schedule_timeout(5*HZ);
246 }
247 finish_wait(&pool->wait, &wait);
248
249 goto repeat_alloc;
250}
251EXPORT_SYMBOL(mempool_alloc);
252
253/**
254 * mempool_free - return an element to the pool.
255 * @element: pool element pointer.
256 * @pool: pointer to the memory pool which was allocated via
257 * mempool_create().
258 *
259 * this function only sleeps if the free_fn() function sleeps.
260 */
261void mempool_free(void *element, mempool_t *pool)
262{
263 unsigned long flags;
264
265 if (unlikely(element == NULL))
266 return;
267
268 smp_mb();
269 if (pool->curr_nr < pool->min_nr) {
270 spin_lock_irqsave(&pool->lock, flags);
271 if (pool->curr_nr < pool->min_nr) {
272 add_element(pool, element);
273 spin_unlock_irqrestore(&pool->lock, flags);
274 wake_up(&pool->wait);
275 return;
276 }
277 spin_unlock_irqrestore(&pool->lock, flags);
278 }
279 pool->free(element, pool->pool_data);
280}
281EXPORT_SYMBOL(mempool_free);
282
283/*
284 * A commonly used alloc and free fn.
285 */
286void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
287{
288 struct kmem_cache *mem = pool_data;
289 return kmem_cache_alloc(mem, gfp_mask);
290}
291EXPORT_SYMBOL(mempool_alloc_slab);
292
293void mempool_free_slab(void *element, void *pool_data)
294{
295 struct kmem_cache *mem = pool_data;
296 kmem_cache_free(mem, element);
297}
298EXPORT_SYMBOL(mempool_free_slab);
299
300/*
301 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
302 * specified by pool_data
303 */
304void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
305{
306 size_t size = (size_t)pool_data;
307 return kmalloc(size, gfp_mask);
308}
309EXPORT_SYMBOL(mempool_kmalloc);
310
311void mempool_kfree(void *element, void *pool_data)
312{
313 kfree(element);
314}
315EXPORT_SYMBOL(mempool_kfree);
316
317/*
318 * A simple mempool-backed page allocator that allocates pages
319 * of the order specified by pool_data.
320 */
321void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
322{
323 int order = (int)(long)pool_data;
324 return alloc_pages(gfp_mask, order);
325}
326EXPORT_SYMBOL(mempool_alloc_pages);
327
328void mempool_free_pages(void *element, void *pool_data)
329{
330 int order = (int)(long)pool_data;
331 __free_pages(element, order);
332}
333EXPORT_SYMBOL(mempool_free_pages);
1/*
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/export.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
30/**
31 * mempool_destroy - deallocate a memory pool
32 * @pool: pointer to the memory pool which was allocated via
33 * mempool_create().
34 *
35 * Free all reserved elements in @pool and @pool itself. This function
36 * only sleeps if the free_fn() function sleeps.
37 */
38void mempool_destroy(mempool_t *pool)
39{
40 while (pool->curr_nr) {
41 void *element = remove_element(pool);
42 pool->free(element, pool->pool_data);
43 }
44 kfree(pool->elements);
45 kfree(pool);
46}
47EXPORT_SYMBOL(mempool_destroy);
48
49/**
50 * mempool_create - create a memory pool
51 * @min_nr: the minimum number of elements guaranteed to be
52 * allocated for this pool.
53 * @alloc_fn: user-defined element-allocation function.
54 * @free_fn: user-defined element-freeing function.
55 * @pool_data: optional private data available to the user-defined functions.
56 *
57 * this function creates and allocates a guaranteed size, preallocated
58 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
59 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
60 * functions might sleep - as long as the mempool_alloc() function is not called
61 * from IRQ contexts.
62 */
63mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
64 mempool_free_t *free_fn, void *pool_data)
65{
66 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);
67}
68EXPORT_SYMBOL(mempool_create);
69
70mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
71 mempool_free_t *free_fn, void *pool_data, int node_id)
72{
73 mempool_t *pool;
74 pool = kmalloc_node(sizeof(*pool), GFP_KERNEL | __GFP_ZERO, node_id);
75 if (!pool)
76 return NULL;
77 pool->elements = kmalloc_node(min_nr * sizeof(void *),
78 GFP_KERNEL, node_id);
79 if (!pool->elements) {
80 kfree(pool);
81 return NULL;
82 }
83 spin_lock_init(&pool->lock);
84 pool->min_nr = min_nr;
85 pool->pool_data = pool_data;
86 init_waitqueue_head(&pool->wait);
87 pool->alloc = alloc_fn;
88 pool->free = free_fn;
89
90 /*
91 * First pre-allocate the guaranteed number of buffers.
92 */
93 while (pool->curr_nr < pool->min_nr) {
94 void *element;
95
96 element = pool->alloc(GFP_KERNEL, pool->pool_data);
97 if (unlikely(!element)) {
98 mempool_destroy(pool);
99 return NULL;
100 }
101 add_element(pool, element);
102 }
103 return pool;
104}
105EXPORT_SYMBOL(mempool_create_node);
106
107/**
108 * mempool_resize - resize an existing memory pool
109 * @pool: pointer to the memory pool which was allocated via
110 * mempool_create().
111 * @new_min_nr: the new minimum number of elements guaranteed to be
112 * allocated for this pool.
113 * @gfp_mask: the usual allocation bitmask.
114 *
115 * This function shrinks/grows the pool. In the case of growing,
116 * it cannot be guaranteed that the pool will be grown to the new
117 * size immediately, but new mempool_free() calls will refill it.
118 *
119 * Note, the caller must guarantee that no mempool_destroy is called
120 * while this function is running. mempool_alloc() & mempool_free()
121 * might be called (eg. from IRQ contexts) while this function executes.
122 */
123int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
124{
125 void *element;
126 void **new_elements;
127 unsigned long flags;
128
129 BUG_ON(new_min_nr <= 0);
130
131 spin_lock_irqsave(&pool->lock, flags);
132 if (new_min_nr <= pool->min_nr) {
133 while (new_min_nr < pool->curr_nr) {
134 element = remove_element(pool);
135 spin_unlock_irqrestore(&pool->lock, flags);
136 pool->free(element, pool->pool_data);
137 spin_lock_irqsave(&pool->lock, flags);
138 }
139 pool->min_nr = new_min_nr;
140 goto out_unlock;
141 }
142 spin_unlock_irqrestore(&pool->lock, flags);
143
144 /* Grow the pool */
145 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
146 if (!new_elements)
147 return -ENOMEM;
148
149 spin_lock_irqsave(&pool->lock, flags);
150 if (unlikely(new_min_nr <= pool->min_nr)) {
151 /* Raced, other resize will do our work */
152 spin_unlock_irqrestore(&pool->lock, flags);
153 kfree(new_elements);
154 goto out;
155 }
156 memcpy(new_elements, pool->elements,
157 pool->curr_nr * sizeof(*new_elements));
158 kfree(pool->elements);
159 pool->elements = new_elements;
160 pool->min_nr = new_min_nr;
161
162 while (pool->curr_nr < pool->min_nr) {
163 spin_unlock_irqrestore(&pool->lock, flags);
164 element = pool->alloc(gfp_mask, pool->pool_data);
165 if (!element)
166 goto out;
167 spin_lock_irqsave(&pool->lock, flags);
168 if (pool->curr_nr < pool->min_nr) {
169 add_element(pool, element);
170 } else {
171 spin_unlock_irqrestore(&pool->lock, flags);
172 pool->free(element, pool->pool_data); /* Raced */
173 goto out;
174 }
175 }
176out_unlock:
177 spin_unlock_irqrestore(&pool->lock, flags);
178out:
179 return 0;
180}
181EXPORT_SYMBOL(mempool_resize);
182
183/**
184 * mempool_alloc - allocate an element from a specific memory pool
185 * @pool: pointer to the memory pool which was allocated via
186 * mempool_create().
187 * @gfp_mask: the usual allocation bitmask.
188 *
189 * this function only sleeps if the alloc_fn() function sleeps or
190 * returns NULL. Note that due to preallocation, this function
191 * *never* fails when called from process contexts. (it might
192 * fail if called from an IRQ context.)
193 */
194void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
195{
196 void *element;
197 unsigned long flags;
198 wait_queue_t wait;
199 gfp_t gfp_temp;
200
201 might_sleep_if(gfp_mask & __GFP_WAIT);
202
203 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
204 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
205 gfp_mask |= __GFP_NOWARN; /* failures are OK */
206
207 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
208
209repeat_alloc:
210
211 element = pool->alloc(gfp_temp, pool->pool_data);
212 if (likely(element != NULL))
213 return element;
214
215 spin_lock_irqsave(&pool->lock, flags);
216 if (likely(pool->curr_nr)) {
217 element = remove_element(pool);
218 spin_unlock_irqrestore(&pool->lock, flags);
219 /* paired with rmb in mempool_free(), read comment there */
220 smp_wmb();
221 return element;
222 }
223
224 /*
225 * We use gfp mask w/o __GFP_WAIT or IO for the first round. If
226 * alloc failed with that and @pool was empty, retry immediately.
227 */
228 if (gfp_temp != gfp_mask) {
229 spin_unlock_irqrestore(&pool->lock, flags);
230 gfp_temp = gfp_mask;
231 goto repeat_alloc;
232 }
233
234 /* We must not sleep if !__GFP_WAIT */
235 if (!(gfp_mask & __GFP_WAIT)) {
236 spin_unlock_irqrestore(&pool->lock, flags);
237 return NULL;
238 }
239
240 /* Let's wait for someone else to return an element to @pool */
241 init_wait(&wait);
242 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
243
244 spin_unlock_irqrestore(&pool->lock, flags);
245
246 /*
247 * FIXME: this should be io_schedule(). The timeout is there as a
248 * workaround for some DM problems in 2.6.18.
249 */
250 io_schedule_timeout(5*HZ);
251
252 finish_wait(&pool->wait, &wait);
253 goto repeat_alloc;
254}
255EXPORT_SYMBOL(mempool_alloc);
256
257/**
258 * mempool_free - return an element to the pool.
259 * @element: pool element pointer.
260 * @pool: pointer to the memory pool which was allocated via
261 * mempool_create().
262 *
263 * this function only sleeps if the free_fn() function sleeps.
264 */
265void mempool_free(void *element, mempool_t *pool)
266{
267 unsigned long flags;
268
269 if (unlikely(element == NULL))
270 return;
271
272 /*
273 * Paired with the wmb in mempool_alloc(). The preceding read is
274 * for @element and the following @pool->curr_nr. This ensures
275 * that the visible value of @pool->curr_nr is from after the
276 * allocation of @element. This is necessary for fringe cases
277 * where @element was passed to this task without going through
278 * barriers.
279 *
280 * For example, assume @p is %NULL at the beginning and one task
281 * performs "p = mempool_alloc(...);" while another task is doing
282 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
283 * may end up using curr_nr value which is from before allocation
284 * of @p without the following rmb.
285 */
286 smp_rmb();
287
288 /*
289 * For correctness, we need a test which is guaranteed to trigger
290 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
291 * without locking achieves that and refilling as soon as possible
292 * is desirable.
293 *
294 * Because curr_nr visible here is always a value after the
295 * allocation of @element, any task which decremented curr_nr below
296 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
297 * incremented to min_nr afterwards. If curr_nr gets incremented
298 * to min_nr after the allocation of @element, the elements
299 * allocated after that are subject to the same guarantee.
300 *
301 * Waiters happen iff curr_nr is 0 and the above guarantee also
302 * ensures that there will be frees which return elements to the
303 * pool waking up the waiters.
304 */
305 if (pool->curr_nr < pool->min_nr) {
306 spin_lock_irqsave(&pool->lock, flags);
307 if (pool->curr_nr < pool->min_nr) {
308 add_element(pool, element);
309 spin_unlock_irqrestore(&pool->lock, flags);
310 wake_up(&pool->wait);
311 return;
312 }
313 spin_unlock_irqrestore(&pool->lock, flags);
314 }
315 pool->free(element, pool->pool_data);
316}
317EXPORT_SYMBOL(mempool_free);
318
319/*
320 * A commonly used alloc and free fn.
321 */
322void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
323{
324 struct kmem_cache *mem = pool_data;
325 return kmem_cache_alloc(mem, gfp_mask);
326}
327EXPORT_SYMBOL(mempool_alloc_slab);
328
329void mempool_free_slab(void *element, void *pool_data)
330{
331 struct kmem_cache *mem = pool_data;
332 kmem_cache_free(mem, element);
333}
334EXPORT_SYMBOL(mempool_free_slab);
335
336/*
337 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
338 * specified by pool_data
339 */
340void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
341{
342 size_t size = (size_t)pool_data;
343 return kmalloc(size, gfp_mask);
344}
345EXPORT_SYMBOL(mempool_kmalloc);
346
347void mempool_kfree(void *element, void *pool_data)
348{
349 kfree(element);
350}
351EXPORT_SYMBOL(mempool_kfree);
352
353/*
354 * A simple mempool-backed page allocator that allocates pages
355 * of the order specified by pool_data.
356 */
357void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
358{
359 int order = (int)(long)pool_data;
360 return alloc_pages(gfp_mask, order);
361}
362EXPORT_SYMBOL(mempool_alloc_pages);
363
364void mempool_free_pages(void *element, void *pool_data)
365{
366 int order = (int)(long)pool_data;
367 __free_pages(element, order);
368}
369EXPORT_SYMBOL(mempool_free_pages);