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)pool_data
;
307 return kmalloc(size
, gfp_mask
);
309 EXPORT_SYMBOL(mempool_kmalloc
);
311 void mempool_kfree(void *element
, void *pool_data
)
315 EXPORT_SYMBOL(mempool_kfree
);
318 * A simple mempool-backed page allocator that allocates pages
319 * of the order specified by pool_data.
321 void *mempool_alloc_pages(gfp_t gfp_mask
, void *pool_data
)
323 int order
= (int)(long)pool_data
;
324 return alloc_pages(gfp_mask
, order
);
326 EXPORT_SYMBOL(mempool_alloc_pages
);
328 void mempool_free_pages(void *element
, void *pool_data
)
330 int order
= (int)(long)pool_data
;
331 __free_pages(element
, order
);
333 EXPORT_SYMBOL(mempool_free_pages
);
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