4 * memory buffer pool support. Such pools are mostly used
5 * for guaranteed, deadlock-free memory allocations during
8 * started by Ingo Molnar, Copyright (C) 2001
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>
18 static void add_element(mempool_t *pool, void *element)
20 BUG_ON(pool->curr_nr >= pool->min_nr);
21 pool->elements[pool->curr_nr++] = element;
24 static void *remove_element(mempool_t *pool)
26 BUG_ON(pool->curr_nr <= 0);
27 return pool->elements[--pool->curr_nr];
30 static void free_pool(mempool_t *pool)
32 while (pool->curr_nr) {
33 void *element = remove_element(pool);
34 pool->free(element, pool->pool_data);
36 kfree(pool->elements);
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.
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
54 mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
55 mempool_free_t *free_fn, void *pool_data)
57 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);
59 EXPORT_SYMBOL(mempool_create);
61 mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
62 mempool_free_t *free_fn, void *pool_data, int node_id)
65 pool = kmalloc_node(sizeof(*pool), GFP_KERNEL | __GFP_ZERO, node_id);
68 pool->elements = kmalloc_node(min_nr * sizeof(void *),
70 if (!pool->elements) {
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;
82 * First pre-allocate the guaranteed number of buffers.
84 while (pool->curr_nr < pool->min_nr) {
87 element = pool->alloc(GFP_KERNEL, pool->pool_data);
88 if (unlikely(!element)) {
92 add_element(pool, element);
96 EXPORT_SYMBOL(mempool_create_node);
99 * mempool_resize - resize an existing memory pool
100 * @pool: pointer to the memory pool which was allocated via
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.
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.
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.
114 int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
120 BUG_ON(new_min_nr <= 0);
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);
130 pool->min_nr = new_min_nr;
133 spin_unlock_irqrestore(&pool->lock, flags);
136 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
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);
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;
153 while (pool->curr_nr < pool->min_nr) {
154 spin_unlock_irqrestore(&pool->lock, flags);
155 element = pool->alloc(gfp_mask, pool->pool_data);
158 spin_lock_irqsave(&pool->lock, flags);
159 if (pool->curr_nr < pool->min_nr) {
160 add_element(pool, element);
162 spin_unlock_irqrestore(&pool->lock, flags);
163 pool->free(element, pool->pool_data); /* Raced */
168 spin_unlock_irqrestore(&pool->lock, flags);
172 EXPORT_SYMBOL(mempool_resize);
175 * mempool_destroy - deallocate a memory pool
176 * @pool: pointer to the memory pool which was allocated via
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().
183 void mempool_destroy(mempool_t *pool)
185 /* Check for outstanding elements */
186 BUG_ON(pool->curr_nr != pool->min_nr);
189 EXPORT_SYMBOL(mempool_destroy);
192 * mempool_alloc - allocate an element from a specific memory pool
193 * @pool: pointer to the memory pool which was allocated via
195 * @gfp_mask: the usual allocation bitmask.
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.)
202 void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
209 might_sleep_if(gfp_mask & __GFP_WAIT);
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 */
215 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
219 element = pool->alloc(gfp_temp, pool->pool_data);
220 if (likely(element != NULL))
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);
229 spin_unlock_irqrestore(&pool->lock, flags);
231 /* We must not sleep in the GFP_ATOMIC case */
232 if (!(gfp_mask & __GFP_WAIT))
235 /* Now start performing page reclaim */
238 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
240 if (!pool->curr_nr) {
242 * FIXME: this should be io_schedule(). The timeout is there
243 * as a workaround for some DM problems in 2.6.18.
245 io_schedule_timeout(5*HZ);
247 finish_wait(&pool->wait, &wait);
251 EXPORT_SYMBOL(mempool_alloc);
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
259 * this function only sleeps if the free_fn() function sleeps.
261 void mempool_free(void *element, mempool_t *pool)
265 if (unlikely(element == NULL))
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);
277 spin_unlock_irqrestore(&pool->lock, flags);
279 pool->free(element, pool->pool_data);
281 EXPORT_SYMBOL(mempool_free);
284 * A commonly used alloc and free fn.
286 void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
288 struct kmem_cache *mem = pool_data;
289 return kmem_cache_alloc(mem, gfp_mask);
291 EXPORT_SYMBOL(mempool_alloc_slab);
293 void mempool_free_slab(void *element, void *pool_data)
295 struct kmem_cache *mem = pool_data;
296 kmem_cache_free(mem, element);
298 EXPORT_SYMBOL(mempool_free_slab);
301 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
302 * specified by pool_data
304 void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
306 size_t size = (size_t)(long)pool_data;
307 return kmalloc(size, gfp_mask);
309 EXPORT_SYMBOL(mempool_kmalloc);
311 void *mempool_kzalloc(gfp_t gfp_mask, void *pool_data)
313 size_t size = (size_t) pool_data;
314 return kzalloc(size, gfp_mask);
316 EXPORT_SYMBOL(mempool_kzalloc);
318 void mempool_kfree(void *element, void *pool_data)
322 EXPORT_SYMBOL(mempool_kfree);
325 * A simple mempool-backed page allocator that allocates pages
326 * of the order specified by pool_data.
328 void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
330 int order = (int)(long)pool_data;
331 return alloc_pages(gfp_mask, order);
333 EXPORT_SYMBOL(mempool_alloc_pages);
335 void mempool_free_pages(void *element, void *pool_data)
337 int order = (int)(long)pool_data;
338 __free_pages(element, order);
340 EXPORT_SYMBOL(mempool_free_pages);