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
, node_id
);
68 memset(pool
, 0, sizeof(*pool
));
69 pool
->elements
= kmalloc_node(min_nr
* sizeof(void *),
71 if (!pool
->elements
) {
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
;
83 * First pre-allocate the guaranteed number of buffers.
85 while (pool
->curr_nr
< pool
->min_nr
) {
88 element
= pool
->alloc(GFP_KERNEL
, pool
->pool_data
);
89 if (unlikely(!element
)) {
93 add_element(pool
, element
);
97 EXPORT_SYMBOL(mempool_create_node
);
100 * mempool_resize - resize an existing memory pool
101 * @pool: pointer to the memory pool which was allocated via
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.
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.
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.
115 int mempool_resize(mempool_t
*pool
, int new_min_nr
, gfp_t gfp_mask
)
121 BUG_ON(new_min_nr
<= 0);
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
);
131 pool
->min_nr
= new_min_nr
;
134 spin_unlock_irqrestore(&pool
->lock
, flags
);
137 new_elements
= kmalloc(new_min_nr
* sizeof(*new_elements
), gfp_mask
);
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
);
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
;
154 while (pool
->curr_nr
< pool
->min_nr
) {
155 spin_unlock_irqrestore(&pool
->lock
, flags
);
156 element
= pool
->alloc(gfp_mask
, pool
->pool_data
);
159 spin_lock_irqsave(&pool
->lock
, flags
);
160 if (pool
->curr_nr
< pool
->min_nr
) {
161 add_element(pool
, element
);
163 spin_unlock_irqrestore(&pool
->lock
, flags
);
164 pool
->free(element
, pool
->pool_data
); /* Raced */
169 spin_unlock_irqrestore(&pool
->lock
, flags
);
173 EXPORT_SYMBOL(mempool_resize
);
176 * mempool_destroy - deallocate a memory pool
177 * @pool: pointer to the memory pool which was allocated via
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().
184 void mempool_destroy(mempool_t
*pool
)
186 if (pool
->curr_nr
!= pool
->min_nr
)
187 BUG(); /* There were outstanding elements */
190 EXPORT_SYMBOL(mempool_destroy
);
193 * mempool_alloc - allocate an element from a specific memory pool
194 * @pool: pointer to the memory pool which was allocated via
196 * @gfp_mask: the usual allocation bitmask.
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.)
203 void * mempool_alloc(mempool_t
*pool
, gfp_t gfp_mask
)
208 unsigned int gfp_temp
;
210 might_sleep_if(gfp_mask
& __GFP_WAIT
);
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 */
216 gfp_temp
= gfp_mask
& ~(__GFP_WAIT
|__GFP_IO
);
220 element
= pool
->alloc(gfp_temp
, pool
->pool_data
);
221 if (likely(element
!= NULL
))
224 spin_lock_irqsave(&pool
->lock
, flags
);
225 if (likely(pool
->curr_nr
)) {
226 element
= remove_element(pool
);
227 spin_unlock_irqrestore(&pool
->lock
, flags
);
230 spin_unlock_irqrestore(&pool
->lock
, flags
);
232 /* We must not sleep in the GFP_ATOMIC case */
233 if (!(gfp_mask
& __GFP_WAIT
))
236 /* Now start performing page reclaim */
239 prepare_to_wait(&pool
->wait
, &wait
, TASK_UNINTERRUPTIBLE
);
243 finish_wait(&pool
->wait
, &wait
);
247 EXPORT_SYMBOL(mempool_alloc
);
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
255 * this function only sleeps if the free_fn() function sleeps.
257 void mempool_free(void *element
, mempool_t
*pool
)
262 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
);
270 spin_unlock_irqrestore(&pool
->lock
, flags
);
272 pool
->free(element
, pool
->pool_data
);
274 EXPORT_SYMBOL(mempool_free
);
277 * A commonly used alloc and free fn.
279 void *mempool_alloc_slab(gfp_t gfp_mask
, void *pool_data
)
281 kmem_cache_t
*mem
= (kmem_cache_t
*) pool_data
;
282 return kmem_cache_alloc(mem
, gfp_mask
);
284 EXPORT_SYMBOL(mempool_alloc_slab
);
286 void mempool_free_slab(void *element
, void *pool_data
)
288 kmem_cache_t
*mem
= (kmem_cache_t
*) pool_data
;
289 kmem_cache_free(mem
, element
);
291 EXPORT_SYMBOL(mempool_free_slab
);