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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/mempool.c
4 *
5 * memory buffer pool support. Such pools are mostly used
6 * for guaranteed, deadlock-free memory allocations during
7 * extreme VM load.
8 *
9 * started by Ingo Molnar, Copyright (C) 2001
10 * debugging by David Rientjes, Copyright (C) 2015
11 */
12
13#include <linux/mm.h>
14#include <linux/slab.h>
15#include <linux/highmem.h>
16#include <linux/kasan.h>
17#include <linux/kmemleak.h>
18#include <linux/export.h>
19#include <linux/mempool.h>
20#include <linux/blkdev.h>
21#include <linux/writeback.h>
22#include "slab.h"
23
24#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
25static void poison_error(mempool_t *pool, void *element, size_t size,
26 size_t byte)
27{
28 const int nr = pool->curr_nr;
29 const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0);
30 const int end = min_t(int, byte + (BITS_PER_LONG / 8), size);
31 int i;
32
33 pr_err("BUG: mempool element poison mismatch\n");
34 pr_err("Mempool %p size %zu\n", pool, size);
35 pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : "");
36 for (i = start; i < end; i++)
37 pr_cont("%x ", *(u8 *)(element + i));
38 pr_cont("%s\n", end < size ? "..." : "");
39 dump_stack();
40}
41
42static void __check_element(mempool_t *pool, void *element, size_t size)
43{
44 u8 *obj = element;
45 size_t i;
46
47 for (i = 0; i < size; i++) {
48 u8 exp = (i < size - 1) ? POISON_FREE : POISON_END;
49
50 if (obj[i] != exp) {
51 poison_error(pool, element, size, i);
52 return;
53 }
54 }
55 memset(obj, POISON_INUSE, size);
56}
57
58static void check_element(mempool_t *pool, void *element)
59{
60 /* Mempools backed by slab allocator */
61 if (pool->free == mempool_free_slab || pool->free == mempool_kfree)
62 __check_element(pool, element, ksize(element));
63
64 /* Mempools backed by page allocator */
65 if (pool->free == mempool_free_pages) {
66 int order = (int)(long)pool->pool_data;
67 void *addr = kmap_atomic((struct page *)element);
68
69 __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
70 kunmap_atomic(addr);
71 }
72}
73
74static void __poison_element(void *element, size_t size)
75{
76 u8 *obj = element;
77
78 memset(obj, POISON_FREE, size - 1);
79 obj[size - 1] = POISON_END;
80}
81
82static void poison_element(mempool_t *pool, void *element)
83{
84 /* Mempools backed by slab allocator */
85 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
86 __poison_element(element, ksize(element));
87
88 /* Mempools backed by page allocator */
89 if (pool->alloc == mempool_alloc_pages) {
90 int order = (int)(long)pool->pool_data;
91 void *addr = kmap_atomic((struct page *)element);
92
93 __poison_element(addr, 1UL << (PAGE_SHIFT + order));
94 kunmap_atomic(addr);
95 }
96}
97#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
98static inline void check_element(mempool_t *pool, void *element)
99{
100}
101static inline void poison_element(mempool_t *pool, void *element)
102{
103}
104#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
105
106static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
107{
108 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
109 kasan_poison_kfree(element, _RET_IP_);
110 if (pool->alloc == mempool_alloc_pages)
111 kasan_free_pages(element, (unsigned long)pool->pool_data);
112}
113
114static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags)
115{
116 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
117 kasan_unpoison_slab(element);
118 if (pool->alloc == mempool_alloc_pages)
119 kasan_alloc_pages(element, (unsigned long)pool->pool_data);
120}
121
122static __always_inline void add_element(mempool_t *pool, void *element)
123{
124 BUG_ON(pool->curr_nr >= pool->min_nr);
125 poison_element(pool, element);
126 kasan_poison_element(pool, element);
127 pool->elements[pool->curr_nr++] = element;
128}
129
130static void *remove_element(mempool_t *pool, gfp_t flags)
131{
132 void *element = pool->elements[--pool->curr_nr];
133
134 BUG_ON(pool->curr_nr < 0);
135 kasan_unpoison_element(pool, element, flags);
136 check_element(pool, element);
137 return element;
138}
139
140/**
141 * mempool_destroy - deallocate a memory pool
142 * @pool: pointer to the memory pool which was allocated via
143 * mempool_create().
144 *
145 * Free all reserved elements in @pool and @pool itself. This function
146 * only sleeps if the free_fn() function sleeps.
147 */
148void mempool_destroy(mempool_t *pool)
149{
150 if (unlikely(!pool))
151 return;
152
153 while (pool->curr_nr) {
154 void *element = remove_element(pool, GFP_KERNEL);
155 pool->free(element, pool->pool_data);
156 }
157 kfree(pool->elements);
158 kfree(pool);
159}
160EXPORT_SYMBOL(mempool_destroy);
161
162/**
163 * mempool_create - create a memory pool
164 * @min_nr: the minimum number of elements guaranteed to be
165 * allocated for this pool.
166 * @alloc_fn: user-defined element-allocation function.
167 * @free_fn: user-defined element-freeing function.
168 * @pool_data: optional private data available to the user-defined functions.
169 *
170 * this function creates and allocates a guaranteed size, preallocated
171 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
172 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
173 * functions might sleep - as long as the mempool_alloc() function is not called
174 * from IRQ contexts.
175 */
176mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
177 mempool_free_t *free_fn, void *pool_data)
178{
179 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
180 GFP_KERNEL, NUMA_NO_NODE);
181}
182EXPORT_SYMBOL(mempool_create);
183
184mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
185 mempool_free_t *free_fn, void *pool_data,
186 gfp_t gfp_mask, int node_id)
187{
188 mempool_t *pool;
189 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
190 if (!pool)
191 return NULL;
192 pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
193 gfp_mask, node_id);
194 if (!pool->elements) {
195 kfree(pool);
196 return NULL;
197 }
198 spin_lock_init(&pool->lock);
199 pool->min_nr = min_nr;
200 pool->pool_data = pool_data;
201 init_waitqueue_head(&pool->wait);
202 pool->alloc = alloc_fn;
203 pool->free = free_fn;
204
205 /*
206 * First pre-allocate the guaranteed number of buffers.
207 */
208 while (pool->curr_nr < pool->min_nr) {
209 void *element;
210
211 element = pool->alloc(gfp_mask, pool->pool_data);
212 if (unlikely(!element)) {
213 mempool_destroy(pool);
214 return NULL;
215 }
216 add_element(pool, element);
217 }
218 return pool;
219}
220EXPORT_SYMBOL(mempool_create_node);
221
222/**
223 * mempool_resize - resize an existing memory pool
224 * @pool: pointer to the memory pool which was allocated via
225 * mempool_create().
226 * @new_min_nr: the new minimum number of elements guaranteed to be
227 * allocated for this pool.
228 *
229 * This function shrinks/grows the pool. In the case of growing,
230 * it cannot be guaranteed that the pool will be grown to the new
231 * size immediately, but new mempool_free() calls will refill it.
232 * This function may sleep.
233 *
234 * Note, the caller must guarantee that no mempool_destroy is called
235 * while this function is running. mempool_alloc() & mempool_free()
236 * might be called (eg. from IRQ contexts) while this function executes.
237 */
238int mempool_resize(mempool_t *pool, int new_min_nr)
239{
240 void *element;
241 void **new_elements;
242 unsigned long flags;
243
244 BUG_ON(new_min_nr <= 0);
245 might_sleep();
246
247 spin_lock_irqsave(&pool->lock, flags);
248 if (new_min_nr <= pool->min_nr) {
249 while (new_min_nr < pool->curr_nr) {
250 element = remove_element(pool, GFP_KERNEL);
251 spin_unlock_irqrestore(&pool->lock, flags);
252 pool->free(element, pool->pool_data);
253 spin_lock_irqsave(&pool->lock, flags);
254 }
255 pool->min_nr = new_min_nr;
256 goto out_unlock;
257 }
258 spin_unlock_irqrestore(&pool->lock, flags);
259
260 /* Grow the pool */
261 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
262 GFP_KERNEL);
263 if (!new_elements)
264 return -ENOMEM;
265
266 spin_lock_irqsave(&pool->lock, flags);
267 if (unlikely(new_min_nr <= pool->min_nr)) {
268 /* Raced, other resize will do our work */
269 spin_unlock_irqrestore(&pool->lock, flags);
270 kfree(new_elements);
271 goto out;
272 }
273 memcpy(new_elements, pool->elements,
274 pool->curr_nr * sizeof(*new_elements));
275 kfree(pool->elements);
276 pool->elements = new_elements;
277 pool->min_nr = new_min_nr;
278
279 while (pool->curr_nr < pool->min_nr) {
280 spin_unlock_irqrestore(&pool->lock, flags);
281 element = pool->alloc(GFP_KERNEL, pool->pool_data);
282 if (!element)
283 goto out;
284 spin_lock_irqsave(&pool->lock, flags);
285 if (pool->curr_nr < pool->min_nr) {
286 add_element(pool, element);
287 } else {
288 spin_unlock_irqrestore(&pool->lock, flags);
289 pool->free(element, pool->pool_data); /* Raced */
290 goto out;
291 }
292 }
293out_unlock:
294 spin_unlock_irqrestore(&pool->lock, flags);
295out:
296 return 0;
297}
298EXPORT_SYMBOL(mempool_resize);
299
300/**
301 * mempool_alloc - allocate an element from a specific memory pool
302 * @pool: pointer to the memory pool which was allocated via
303 * mempool_create().
304 * @gfp_mask: the usual allocation bitmask.
305 *
306 * this function only sleeps if the alloc_fn() function sleeps or
307 * returns NULL. Note that due to preallocation, this function
308 * *never* fails when called from process contexts. (it might
309 * fail if called from an IRQ context.)
310 * Note: using __GFP_ZERO is not supported.
311 */
312void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
313{
314 void *element;
315 unsigned long flags;
316 wait_queue_entry_t wait;
317 gfp_t gfp_temp;
318
319 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
320 might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
321
322 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
323 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
324 gfp_mask |= __GFP_NOWARN; /* failures are OK */
325
326 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
327
328repeat_alloc:
329
330 element = pool->alloc(gfp_temp, pool->pool_data);
331 if (likely(element != NULL))
332 return element;
333
334 spin_lock_irqsave(&pool->lock, flags);
335 if (likely(pool->curr_nr)) {
336 element = remove_element(pool, gfp_temp);
337 spin_unlock_irqrestore(&pool->lock, flags);
338 /* paired with rmb in mempool_free(), read comment there */
339 smp_wmb();
340 /*
341 * Update the allocation stack trace as this is more useful
342 * for debugging.
343 */
344 kmemleak_update_trace(element);
345 return element;
346 }
347
348 /*
349 * We use gfp mask w/o direct reclaim or IO for the first round. If
350 * alloc failed with that and @pool was empty, retry immediately.
351 */
352 if (gfp_temp != gfp_mask) {
353 spin_unlock_irqrestore(&pool->lock, flags);
354 gfp_temp = gfp_mask;
355 goto repeat_alloc;
356 }
357
358 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
359 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
360 spin_unlock_irqrestore(&pool->lock, flags);
361 return NULL;
362 }
363
364 /* Let's wait for someone else to return an element to @pool */
365 init_wait(&wait);
366 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
367
368 spin_unlock_irqrestore(&pool->lock, flags);
369
370 /*
371 * FIXME: this should be io_schedule(). The timeout is there as a
372 * workaround for some DM problems in 2.6.18.
373 */
374 io_schedule_timeout(5*HZ);
375
376 finish_wait(&pool->wait, &wait);
377 goto repeat_alloc;
378}
379EXPORT_SYMBOL(mempool_alloc);
380
381/**
382 * mempool_free - return an element to the pool.
383 * @element: pool element pointer.
384 * @pool: pointer to the memory pool which was allocated via
385 * mempool_create().
386 *
387 * this function only sleeps if the free_fn() function sleeps.
388 */
389void mempool_free(void *element, mempool_t *pool)
390{
391 unsigned long flags;
392
393 if (unlikely(element == NULL))
394 return;
395
396 /*
397 * Paired with the wmb in mempool_alloc(). The preceding read is
398 * for @element and the following @pool->curr_nr. This ensures
399 * that the visible value of @pool->curr_nr is from after the
400 * allocation of @element. This is necessary for fringe cases
401 * where @element was passed to this task without going through
402 * barriers.
403 *
404 * For example, assume @p is %NULL at the beginning and one task
405 * performs "p = mempool_alloc(...);" while another task is doing
406 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
407 * may end up using curr_nr value which is from before allocation
408 * of @p without the following rmb.
409 */
410 smp_rmb();
411
412 /*
413 * For correctness, we need a test which is guaranteed to trigger
414 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
415 * without locking achieves that and refilling as soon as possible
416 * is desirable.
417 *
418 * Because curr_nr visible here is always a value after the
419 * allocation of @element, any task which decremented curr_nr below
420 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
421 * incremented to min_nr afterwards. If curr_nr gets incremented
422 * to min_nr after the allocation of @element, the elements
423 * allocated after that are subject to the same guarantee.
424 *
425 * Waiters happen iff curr_nr is 0 and the above guarantee also
426 * ensures that there will be frees which return elements to the
427 * pool waking up the waiters.
428 */
429 if (unlikely(pool->curr_nr < pool->min_nr)) {
430 spin_lock_irqsave(&pool->lock, flags);
431 if (likely(pool->curr_nr < pool->min_nr)) {
432 add_element(pool, element);
433 spin_unlock_irqrestore(&pool->lock, flags);
434 wake_up(&pool->wait);
435 return;
436 }
437 spin_unlock_irqrestore(&pool->lock, flags);
438 }
439 pool->free(element, pool->pool_data);
440}
441EXPORT_SYMBOL(mempool_free);
442
443/*
444 * A commonly used alloc and free fn.
445 */
446void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
447{
448 struct kmem_cache *mem = pool_data;
449 VM_BUG_ON(mem->ctor);
450 return kmem_cache_alloc(mem, gfp_mask);
451}
452EXPORT_SYMBOL(mempool_alloc_slab);
453
454void mempool_free_slab(void *element, void *pool_data)
455{
456 struct kmem_cache *mem = pool_data;
457 kmem_cache_free(mem, element);
458}
459EXPORT_SYMBOL(mempool_free_slab);
460
461/*
462 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
463 * specified by pool_data
464 */
465void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
466{
467 size_t size = (size_t)pool_data;
468 return kmalloc(size, gfp_mask);
469}
470EXPORT_SYMBOL(mempool_kmalloc);
471
472void mempool_kfree(void *element, void *pool_data)
473{
474 kfree(element);
475}
476EXPORT_SYMBOL(mempool_kfree);
477
478/*
479 * A simple mempool-backed page allocator that allocates pages
480 * of the order specified by pool_data.
481 */
482void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
483{
484 int order = (int)(long)pool_data;
485 return alloc_pages(gfp_mask, order);
486}
487EXPORT_SYMBOL(mempool_alloc_pages);
488
489void mempool_free_pages(void *element, void *pool_data)
490{
491 int order = (int)(long)pool_data;
492 __free_pages(element, order);
493}
494EXPORT_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);