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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 * debugging by David Rientjes, Copyright (C) 2015
10 */
11
12#include <linux/mm.h>
13#include <linux/slab.h>
14#include <linux/highmem.h>
15#include <linux/kasan.h>
16#include <linux/kmemleak.h>
17#include <linux/export.h>
18#include <linux/mempool.h>
19#include <linux/blkdev.h>
20#include <linux/writeback.h>
21#include "slab.h"
22
23#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
24static void poison_error(mempool_t *pool, void *element, size_t size,
25 size_t byte)
26{
27 const int nr = pool->curr_nr;
28 const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0);
29 const int end = min_t(int, byte + (BITS_PER_LONG / 8), size);
30 int i;
31
32 pr_err("BUG: mempool element poison mismatch\n");
33 pr_err("Mempool %p size %zu\n", pool, size);
34 pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : "");
35 for (i = start; i < end; i++)
36 pr_cont("%x ", *(u8 *)(element + i));
37 pr_cont("%s\n", end < size ? "..." : "");
38 dump_stack();
39}
40
41static void __check_element(mempool_t *pool, void *element, size_t size)
42{
43 u8 *obj = element;
44 size_t i;
45
46 for (i = 0; i < size; i++) {
47 u8 exp = (i < size - 1) ? POISON_FREE : POISON_END;
48
49 if (obj[i] != exp) {
50 poison_error(pool, element, size, i);
51 return;
52 }
53 }
54 memset(obj, POISON_INUSE, size);
55}
56
57static void check_element(mempool_t *pool, void *element)
58{
59 /* Mempools backed by slab allocator */
60 if (pool->free == mempool_free_slab || pool->free == mempool_kfree)
61 __check_element(pool, element, ksize(element));
62
63 /* Mempools backed by page allocator */
64 if (pool->free == mempool_free_pages) {
65 int order = (int)(long)pool->pool_data;
66 void *addr = kmap_atomic((struct page *)element);
67
68 __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
69 kunmap_atomic(addr);
70 }
71}
72
73static void __poison_element(void *element, size_t size)
74{
75 u8 *obj = element;
76
77 memset(obj, POISON_FREE, size - 1);
78 obj[size - 1] = POISON_END;
79}
80
81static void poison_element(mempool_t *pool, void *element)
82{
83 /* Mempools backed by slab allocator */
84 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
85 __poison_element(element, ksize(element));
86
87 /* Mempools backed by page allocator */
88 if (pool->alloc == mempool_alloc_pages) {
89 int order = (int)(long)pool->pool_data;
90 void *addr = kmap_atomic((struct page *)element);
91
92 __poison_element(addr, 1UL << (PAGE_SHIFT + order));
93 kunmap_atomic(addr);
94 }
95}
96#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
97static inline void check_element(mempool_t *pool, void *element)
98{
99}
100static inline void poison_element(mempool_t *pool, void *element)
101{
102}
103#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
104
105static void kasan_poison_element(mempool_t *pool, void *element)
106{
107 if (pool->alloc == mempool_alloc_slab)
108 kasan_slab_free(pool->pool_data, element);
109 if (pool->alloc == mempool_kmalloc)
110 kasan_kfree(element);
111 if (pool->alloc == mempool_alloc_pages)
112 kasan_free_pages(element, (unsigned long)pool->pool_data);
113}
114
115static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags)
116{
117 if (pool->alloc == mempool_alloc_slab)
118 kasan_slab_alloc(pool->pool_data, element, flags);
119 if (pool->alloc == mempool_kmalloc)
120 kasan_krealloc(element, (size_t)pool->pool_data, flags);
121 if (pool->alloc == mempool_alloc_pages)
122 kasan_alloc_pages(element, (unsigned long)pool->pool_data);
123}
124
125static void add_element(mempool_t *pool, void *element)
126{
127 BUG_ON(pool->curr_nr >= pool->min_nr);
128 poison_element(pool, element);
129 kasan_poison_element(pool, element);
130 pool->elements[pool->curr_nr++] = element;
131}
132
133static void *remove_element(mempool_t *pool, gfp_t flags)
134{
135 void *element = pool->elements[--pool->curr_nr];
136
137 BUG_ON(pool->curr_nr < 0);
138 kasan_unpoison_element(pool, element, flags);
139 check_element(pool, element);
140 return element;
141}
142
143/**
144 * mempool_destroy - deallocate a memory pool
145 * @pool: pointer to the memory pool which was allocated via
146 * mempool_create().
147 *
148 * Free all reserved elements in @pool and @pool itself. This function
149 * only sleeps if the free_fn() function sleeps.
150 */
151void mempool_destroy(mempool_t *pool)
152{
153 if (unlikely(!pool))
154 return;
155
156 while (pool->curr_nr) {
157 void *element = remove_element(pool, GFP_KERNEL);
158 pool->free(element, pool->pool_data);
159 }
160 kfree(pool->elements);
161 kfree(pool);
162}
163EXPORT_SYMBOL(mempool_destroy);
164
165/**
166 * mempool_create - create a memory pool
167 * @min_nr: the minimum number of elements guaranteed to be
168 * allocated for this pool.
169 * @alloc_fn: user-defined element-allocation function.
170 * @free_fn: user-defined element-freeing function.
171 * @pool_data: optional private data available to the user-defined functions.
172 *
173 * this function creates and allocates a guaranteed size, preallocated
174 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
175 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
176 * functions might sleep - as long as the mempool_alloc() function is not called
177 * from IRQ contexts.
178 */
179mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
180 mempool_free_t *free_fn, void *pool_data)
181{
182 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
183 GFP_KERNEL, NUMA_NO_NODE);
184}
185EXPORT_SYMBOL(mempool_create);
186
187mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
188 mempool_free_t *free_fn, void *pool_data,
189 gfp_t gfp_mask, int node_id)
190{
191 mempool_t *pool;
192 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
193 if (!pool)
194 return NULL;
195 pool->elements = kmalloc_node(min_nr * sizeof(void *),
196 gfp_mask, node_id);
197 if (!pool->elements) {
198 kfree(pool);
199 return NULL;
200 }
201 spin_lock_init(&pool->lock);
202 pool->min_nr = min_nr;
203 pool->pool_data = pool_data;
204 init_waitqueue_head(&pool->wait);
205 pool->alloc = alloc_fn;
206 pool->free = free_fn;
207
208 /*
209 * First pre-allocate the guaranteed number of buffers.
210 */
211 while (pool->curr_nr < pool->min_nr) {
212 void *element;
213
214 element = pool->alloc(gfp_mask, pool->pool_data);
215 if (unlikely(!element)) {
216 mempool_destroy(pool);
217 return NULL;
218 }
219 add_element(pool, element);
220 }
221 return pool;
222}
223EXPORT_SYMBOL(mempool_create_node);
224
225/**
226 * mempool_resize - resize an existing memory pool
227 * @pool: pointer to the memory pool which was allocated via
228 * mempool_create().
229 * @new_min_nr: the new minimum number of elements guaranteed to be
230 * allocated for this pool.
231 *
232 * This function shrinks/grows the pool. In the case of growing,
233 * it cannot be guaranteed that the pool will be grown to the new
234 * size immediately, but new mempool_free() calls will refill it.
235 * This function may sleep.
236 *
237 * Note, the caller must guarantee that no mempool_destroy is called
238 * while this function is running. mempool_alloc() & mempool_free()
239 * might be called (eg. from IRQ contexts) while this function executes.
240 */
241int mempool_resize(mempool_t *pool, int new_min_nr)
242{
243 void *element;
244 void **new_elements;
245 unsigned long flags;
246
247 BUG_ON(new_min_nr <= 0);
248 might_sleep();
249
250 spin_lock_irqsave(&pool->lock, flags);
251 if (new_min_nr <= pool->min_nr) {
252 while (new_min_nr < pool->curr_nr) {
253 element = remove_element(pool, GFP_KERNEL);
254 spin_unlock_irqrestore(&pool->lock, flags);
255 pool->free(element, pool->pool_data);
256 spin_lock_irqsave(&pool->lock, flags);
257 }
258 pool->min_nr = new_min_nr;
259 goto out_unlock;
260 }
261 spin_unlock_irqrestore(&pool->lock, flags);
262
263 /* Grow the pool */
264 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
265 GFP_KERNEL);
266 if (!new_elements)
267 return -ENOMEM;
268
269 spin_lock_irqsave(&pool->lock, flags);
270 if (unlikely(new_min_nr <= pool->min_nr)) {
271 /* Raced, other resize will do our work */
272 spin_unlock_irqrestore(&pool->lock, flags);
273 kfree(new_elements);
274 goto out;
275 }
276 memcpy(new_elements, pool->elements,
277 pool->curr_nr * sizeof(*new_elements));
278 kfree(pool->elements);
279 pool->elements = new_elements;
280 pool->min_nr = new_min_nr;
281
282 while (pool->curr_nr < pool->min_nr) {
283 spin_unlock_irqrestore(&pool->lock, flags);
284 element = pool->alloc(GFP_KERNEL, pool->pool_data);
285 if (!element)
286 goto out;
287 spin_lock_irqsave(&pool->lock, flags);
288 if (pool->curr_nr < pool->min_nr) {
289 add_element(pool, element);
290 } else {
291 spin_unlock_irqrestore(&pool->lock, flags);
292 pool->free(element, pool->pool_data); /* Raced */
293 goto out;
294 }
295 }
296out_unlock:
297 spin_unlock_irqrestore(&pool->lock, flags);
298out:
299 return 0;
300}
301EXPORT_SYMBOL(mempool_resize);
302
303/**
304 * mempool_alloc - allocate an element from a specific memory pool
305 * @pool: pointer to the memory pool which was allocated via
306 * mempool_create().
307 * @gfp_mask: the usual allocation bitmask.
308 *
309 * this function only sleeps if the alloc_fn() function sleeps or
310 * returns NULL. Note that due to preallocation, this function
311 * *never* fails when called from process contexts. (it might
312 * fail if called from an IRQ context.)
313 * Note: neither __GFP_NOMEMALLOC nor __GFP_ZERO are supported.
314 */
315void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
316{
317 void *element;
318 unsigned long flags;
319 wait_queue_t wait;
320 gfp_t gfp_temp;
321
322 /* If oom killed, memory reserves are essential to prevent livelock */
323 VM_WARN_ON_ONCE(gfp_mask & __GFP_NOMEMALLOC);
324 /* No element size to zero on allocation */
325 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
326
327 might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
328
329 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
330 gfp_mask |= __GFP_NOWARN; /* failures are OK */
331
332 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
333
334repeat_alloc:
335 if (likely(pool->curr_nr)) {
336 /*
337 * Don't allocate from emergency reserves if there are
338 * elements available. This check is racy, but it will
339 * be rechecked each loop.
340 */
341 gfp_temp |= __GFP_NOMEMALLOC;
342 }
343
344 element = pool->alloc(gfp_temp, pool->pool_data);
345 if (likely(element != NULL))
346 return element;
347
348 spin_lock_irqsave(&pool->lock, flags);
349 if (likely(pool->curr_nr)) {
350 element = remove_element(pool, gfp_temp);
351 spin_unlock_irqrestore(&pool->lock, flags);
352 /* paired with rmb in mempool_free(), read comment there */
353 smp_wmb();
354 /*
355 * Update the allocation stack trace as this is more useful
356 * for debugging.
357 */
358 kmemleak_update_trace(element);
359 return element;
360 }
361
362 /*
363 * We use gfp mask w/o direct reclaim or IO for the first round. If
364 * alloc failed with that and @pool was empty, retry immediately.
365 */
366 if ((gfp_temp & ~__GFP_NOMEMALLOC) != gfp_mask) {
367 spin_unlock_irqrestore(&pool->lock, flags);
368 gfp_temp = gfp_mask;
369 goto repeat_alloc;
370 }
371 gfp_temp = gfp_mask;
372
373 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
374 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
375 spin_unlock_irqrestore(&pool->lock, flags);
376 return NULL;
377 }
378
379 /* Let's wait for someone else to return an element to @pool */
380 init_wait(&wait);
381 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
382
383 spin_unlock_irqrestore(&pool->lock, flags);
384
385 /*
386 * FIXME: this should be io_schedule(). The timeout is there as a
387 * workaround for some DM problems in 2.6.18.
388 */
389 io_schedule_timeout(5*HZ);
390
391 finish_wait(&pool->wait, &wait);
392 goto repeat_alloc;
393}
394EXPORT_SYMBOL(mempool_alloc);
395
396/**
397 * mempool_free - return an element to the pool.
398 * @element: pool element pointer.
399 * @pool: pointer to the memory pool which was allocated via
400 * mempool_create().
401 *
402 * this function only sleeps if the free_fn() function sleeps.
403 */
404void mempool_free(void *element, mempool_t *pool)
405{
406 unsigned long flags;
407
408 if (unlikely(element == NULL))
409 return;
410
411 /*
412 * Paired with the wmb in mempool_alloc(). The preceding read is
413 * for @element and the following @pool->curr_nr. This ensures
414 * that the visible value of @pool->curr_nr is from after the
415 * allocation of @element. This is necessary for fringe cases
416 * where @element was passed to this task without going through
417 * barriers.
418 *
419 * For example, assume @p is %NULL at the beginning and one task
420 * performs "p = mempool_alloc(...);" while another task is doing
421 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
422 * may end up using curr_nr value which is from before allocation
423 * of @p without the following rmb.
424 */
425 smp_rmb();
426
427 /*
428 * For correctness, we need a test which is guaranteed to trigger
429 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
430 * without locking achieves that and refilling as soon as possible
431 * is desirable.
432 *
433 * Because curr_nr visible here is always a value after the
434 * allocation of @element, any task which decremented curr_nr below
435 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
436 * incremented to min_nr afterwards. If curr_nr gets incremented
437 * to min_nr after the allocation of @element, the elements
438 * allocated after that are subject to the same guarantee.
439 *
440 * Waiters happen iff curr_nr is 0 and the above guarantee also
441 * ensures that there will be frees which return elements to the
442 * pool waking up the waiters.
443 */
444 if (unlikely(pool->curr_nr < pool->min_nr)) {
445 spin_lock_irqsave(&pool->lock, flags);
446 if (likely(pool->curr_nr < pool->min_nr)) {
447 add_element(pool, element);
448 spin_unlock_irqrestore(&pool->lock, flags);
449 wake_up(&pool->wait);
450 return;
451 }
452 spin_unlock_irqrestore(&pool->lock, flags);
453 }
454 pool->free(element, pool->pool_data);
455}
456EXPORT_SYMBOL(mempool_free);
457
458/*
459 * A commonly used alloc and free fn.
460 */
461void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
462{
463 struct kmem_cache *mem = pool_data;
464 VM_BUG_ON(mem->ctor);
465 return kmem_cache_alloc(mem, gfp_mask);
466}
467EXPORT_SYMBOL(mempool_alloc_slab);
468
469void mempool_free_slab(void *element, void *pool_data)
470{
471 struct kmem_cache *mem = pool_data;
472 kmem_cache_free(mem, element);
473}
474EXPORT_SYMBOL(mempool_free_slab);
475
476/*
477 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
478 * specified by pool_data
479 */
480void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
481{
482 size_t size = (size_t)pool_data;
483 return kmalloc(size, gfp_mask);
484}
485EXPORT_SYMBOL(mempool_kmalloc);
486
487void mempool_kfree(void *element, void *pool_data)
488{
489 kfree(element);
490}
491EXPORT_SYMBOL(mempool_kfree);
492
493/*
494 * A simple mempool-backed page allocator that allocates pages
495 * of the order specified by pool_data.
496 */
497void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
498{
499 int order = (int)(long)pool_data;
500 return alloc_pages(gfp_mask, order);
501}
502EXPORT_SYMBOL(mempool_alloc_pages);
503
504void mempool_free_pages(void *element, void *pool_data)
505{
506 int order = (int)(long)pool_data;
507 __free_pages(element, order);
508}
509EXPORT_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,
67 GFP_KERNEL, NUMA_NO_NODE);
68}
69EXPORT_SYMBOL(mempool_create);
70
71mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
72 mempool_free_t *free_fn, void *pool_data,
73 gfp_t gfp_mask, int node_id)
74{
75 mempool_t *pool;
76 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
77 if (!pool)
78 return NULL;
79 pool->elements = kmalloc_node(min_nr * sizeof(void *),
80 gfp_mask, node_id);
81 if (!pool->elements) {
82 kfree(pool);
83 return NULL;
84 }
85 spin_lock_init(&pool->lock);
86 pool->min_nr = min_nr;
87 pool->pool_data = pool_data;
88 init_waitqueue_head(&pool->wait);
89 pool->alloc = alloc_fn;
90 pool->free = free_fn;
91
92 /*
93 * First pre-allocate the guaranteed number of buffers.
94 */
95 while (pool->curr_nr < pool->min_nr) {
96 void *element;
97
98 element = pool->alloc(gfp_mask, pool->pool_data);
99 if (unlikely(!element)) {
100 mempool_destroy(pool);
101 return NULL;
102 }
103 add_element(pool, element);
104 }
105 return pool;
106}
107EXPORT_SYMBOL(mempool_create_node);
108
109/**
110 * mempool_resize - resize an existing memory pool
111 * @pool: pointer to the memory pool which was allocated via
112 * mempool_create().
113 * @new_min_nr: the new minimum number of elements guaranteed to be
114 * allocated for this pool.
115 * @gfp_mask: the usual allocation bitmask.
116 *
117 * This function shrinks/grows the pool. In the case of growing,
118 * it cannot be guaranteed that the pool will be grown to the new
119 * size immediately, but new mempool_free() calls will refill it.
120 *
121 * Note, the caller must guarantee that no mempool_destroy is called
122 * while this function is running. mempool_alloc() & mempool_free()
123 * might be called (eg. from IRQ contexts) while this function executes.
124 */
125int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
126{
127 void *element;
128 void **new_elements;
129 unsigned long flags;
130
131 BUG_ON(new_min_nr <= 0);
132
133 spin_lock_irqsave(&pool->lock, flags);
134 if (new_min_nr <= pool->min_nr) {
135 while (new_min_nr < pool->curr_nr) {
136 element = remove_element(pool);
137 spin_unlock_irqrestore(&pool->lock, flags);
138 pool->free(element, pool->pool_data);
139 spin_lock_irqsave(&pool->lock, flags);
140 }
141 pool->min_nr = new_min_nr;
142 goto out_unlock;
143 }
144 spin_unlock_irqrestore(&pool->lock, flags);
145
146 /* Grow the pool */
147 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
148 if (!new_elements)
149 return -ENOMEM;
150
151 spin_lock_irqsave(&pool->lock, flags);
152 if (unlikely(new_min_nr <= pool->min_nr)) {
153 /* Raced, other resize will do our work */
154 spin_unlock_irqrestore(&pool->lock, flags);
155 kfree(new_elements);
156 goto out;
157 }
158 memcpy(new_elements, pool->elements,
159 pool->curr_nr * sizeof(*new_elements));
160 kfree(pool->elements);
161 pool->elements = new_elements;
162 pool->min_nr = new_min_nr;
163
164 while (pool->curr_nr < pool->min_nr) {
165 spin_unlock_irqrestore(&pool->lock, flags);
166 element = pool->alloc(gfp_mask, pool->pool_data);
167 if (!element)
168 goto out;
169 spin_lock_irqsave(&pool->lock, flags);
170 if (pool->curr_nr < pool->min_nr) {
171 add_element(pool, element);
172 } else {
173 spin_unlock_irqrestore(&pool->lock, flags);
174 pool->free(element, pool->pool_data); /* Raced */
175 goto out;
176 }
177 }
178out_unlock:
179 spin_unlock_irqrestore(&pool->lock, flags);
180out:
181 return 0;
182}
183EXPORT_SYMBOL(mempool_resize);
184
185/**
186 * mempool_alloc - allocate an element from a specific memory pool
187 * @pool: pointer to the memory pool which was allocated via
188 * mempool_create().
189 * @gfp_mask: the usual allocation bitmask.
190 *
191 * this function only sleeps if the alloc_fn() function sleeps or
192 * returns NULL. Note that due to preallocation, this function
193 * *never* fails when called from process contexts. (it might
194 * fail if called from an IRQ context.)
195 */
196void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
197{
198 void *element;
199 unsigned long flags;
200 wait_queue_t wait;
201 gfp_t gfp_temp;
202
203 might_sleep_if(gfp_mask & __GFP_WAIT);
204
205 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
206 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
207 gfp_mask |= __GFP_NOWARN; /* failures are OK */
208
209 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
210
211repeat_alloc:
212
213 element = pool->alloc(gfp_temp, pool->pool_data);
214 if (likely(element != NULL))
215 return element;
216
217 spin_lock_irqsave(&pool->lock, flags);
218 if (likely(pool->curr_nr)) {
219 element = remove_element(pool);
220 spin_unlock_irqrestore(&pool->lock, flags);
221 /* paired with rmb in mempool_free(), read comment there */
222 smp_wmb();
223 return element;
224 }
225
226 /*
227 * We use gfp mask w/o __GFP_WAIT or IO for the first round. If
228 * alloc failed with that and @pool was empty, retry immediately.
229 */
230 if (gfp_temp != gfp_mask) {
231 spin_unlock_irqrestore(&pool->lock, flags);
232 gfp_temp = gfp_mask;
233 goto repeat_alloc;
234 }
235
236 /* We must not sleep if !__GFP_WAIT */
237 if (!(gfp_mask & __GFP_WAIT)) {
238 spin_unlock_irqrestore(&pool->lock, flags);
239 return NULL;
240 }
241
242 /* Let's wait for someone else to return an element to @pool */
243 init_wait(&wait);
244 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
245
246 spin_unlock_irqrestore(&pool->lock, flags);
247
248 /*
249 * FIXME: this should be io_schedule(). The timeout is there as a
250 * workaround for some DM problems in 2.6.18.
251 */
252 io_schedule_timeout(5*HZ);
253
254 finish_wait(&pool->wait, &wait);
255 goto repeat_alloc;
256}
257EXPORT_SYMBOL(mempool_alloc);
258
259/**
260 * mempool_free - return an element to the pool.
261 * @element: pool element pointer.
262 * @pool: pointer to the memory pool which was allocated via
263 * mempool_create().
264 *
265 * this function only sleeps if the free_fn() function sleeps.
266 */
267void mempool_free(void *element, mempool_t *pool)
268{
269 unsigned long flags;
270
271 if (unlikely(element == NULL))
272 return;
273
274 /*
275 * Paired with the wmb in mempool_alloc(). The preceding read is
276 * for @element and the following @pool->curr_nr. This ensures
277 * that the visible value of @pool->curr_nr is from after the
278 * allocation of @element. This is necessary for fringe cases
279 * where @element was passed to this task without going through
280 * barriers.
281 *
282 * For example, assume @p is %NULL at the beginning and one task
283 * performs "p = mempool_alloc(...);" while another task is doing
284 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
285 * may end up using curr_nr value which is from before allocation
286 * of @p without the following rmb.
287 */
288 smp_rmb();
289
290 /*
291 * For correctness, we need a test which is guaranteed to trigger
292 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
293 * without locking achieves that and refilling as soon as possible
294 * is desirable.
295 *
296 * Because curr_nr visible here is always a value after the
297 * allocation of @element, any task which decremented curr_nr below
298 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
299 * incremented to min_nr afterwards. If curr_nr gets incremented
300 * to min_nr after the allocation of @element, the elements
301 * allocated after that are subject to the same guarantee.
302 *
303 * Waiters happen iff curr_nr is 0 and the above guarantee also
304 * ensures that there will be frees which return elements to the
305 * pool waking up the waiters.
306 */
307 if (unlikely(pool->curr_nr < pool->min_nr)) {
308 spin_lock_irqsave(&pool->lock, flags);
309 if (likely(pool->curr_nr < pool->min_nr)) {
310 add_element(pool, element);
311 spin_unlock_irqrestore(&pool->lock, flags);
312 wake_up(&pool->wait);
313 return;
314 }
315 spin_unlock_irqrestore(&pool->lock, flags);
316 }
317 pool->free(element, pool->pool_data);
318}
319EXPORT_SYMBOL(mempool_free);
320
321/*
322 * A commonly used alloc and free fn.
323 */
324void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
325{
326 struct kmem_cache *mem = pool_data;
327 return kmem_cache_alloc(mem, gfp_mask);
328}
329EXPORT_SYMBOL(mempool_alloc_slab);
330
331void mempool_free_slab(void *element, void *pool_data)
332{
333 struct kmem_cache *mem = pool_data;
334 kmem_cache_free(mem, element);
335}
336EXPORT_SYMBOL(mempool_free_slab);
337
338/*
339 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
340 * specified by pool_data
341 */
342void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
343{
344 size_t size = (size_t)pool_data;
345 return kmalloc(size, gfp_mask);
346}
347EXPORT_SYMBOL(mempool_kmalloc);
348
349void mempool_kfree(void *element, void *pool_data)
350{
351 kfree(element);
352}
353EXPORT_SYMBOL(mempool_kfree);
354
355/*
356 * A simple mempool-backed page allocator that allocates pages
357 * of the order specified by pool_data.
358 */
359void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
360{
361 int order = (int)(long)pool_data;
362 return alloc_pages(gfp_mask, order);
363}
364EXPORT_SYMBOL(mempool_alloc_pages);
365
366void mempool_free_pages(void *element, void *pool_data)
367{
368 int order = (int)(long)pool_data;
369 __free_pages(element, order);
370}
371EXPORT_SYMBOL(mempool_free_pages);