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Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
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
David Rientjesbdfedb72015-04-15 16:14:17 -070010 * debugging by David Rientjes, Copyright (C) 2015
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 */
12
13#include <linux/mm.h>
14#include <linux/slab.h>
David Rientjesbdfedb72015-04-15 16:14:17 -070015#include <linux/highmem.h>
Andrey Ryabinin92393612015-04-15 16:15:05 -070016#include <linux/kasan.h>
Catalin Marinas17411962014-06-06 14:38:19 -070017#include <linux/kmemleak.h>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040018#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/mempool.h>
20#include <linux/blkdev.h>
21#include <linux/writeback.h>
David Rientjese244c9e2015-04-15 16:14:14 -070022#include "slab.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
David Rientjesbdfedb72015-04-15 16:14:17 -070024#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
Dmitry Vyukov6860f632018-02-06 15:36:30 -0800106static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
Andrey Ryabinin92393612015-04-15 16:15:05 -0700107{
Andrey Ryabinin9b75a862016-06-24 14:49:34 -0700108 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
Dmitry Vyukov6860f632018-02-06 15:36:30 -0800109 kasan_poison_kfree(element, _RET_IP_);
Andrey Ryabinin92393612015-04-15 16:15:05 -0700110 if (pool->alloc == mempool_alloc_pages)
111 kasan_free_pages(element, (unsigned long)pool->pool_data);
112}
113
Jia-Ju Bai8cded862018-08-17 15:45:22 -0700114static void kasan_unpoison_element(mempool_t *pool, void *element)
Andrey Ryabinin92393612015-04-15 16:15:05 -0700115{
Andrey Ryabinin9b75a862016-06-24 14:49:34 -0700116 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
117 kasan_unpoison_slab(element);
Andrey Ryabinin92393612015-04-15 16:15:05 -0700118 if (pool->alloc == mempool_alloc_pages)
119 kasan_alloc_pages(element, (unsigned long)pool->pool_data);
120}
121
Dmitry Vyukov6860f632018-02-06 15:36:30 -0800122static __always_inline void add_element(mempool_t *pool, void *element)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
124 BUG_ON(pool->curr_nr >= pool->min_nr);
David Rientjesbdfedb72015-04-15 16:14:17 -0700125 poison_element(pool, element);
Andrey Ryabinin92393612015-04-15 16:15:05 -0700126 kasan_poison_element(pool, element);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 pool->elements[pool->curr_nr++] = element;
128}
129
Jia-Ju Bai8cded862018-08-17 15:45:22 -0700130static void *remove_element(mempool_t *pool)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131{
David Rientjesbdfedb72015-04-15 16:14:17 -0700132 void *element = pool->elements[--pool->curr_nr];
133
134 BUG_ON(pool->curr_nr < 0);
Jia-Ju Bai8cded862018-08-17 15:45:22 -0700135 kasan_unpoison_element(pool, element);
Matthew Dawson76401312016-03-11 13:08:07 -0800136 check_element(pool, element);
David Rientjesbdfedb72015-04-15 16:14:17 -0700137 return element;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138}
139
Tejun Heo0565d312012-01-10 15:08:26 -0800140/**
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700141 * mempool_exit - exit a mempool initialized with mempool_init()
142 * @pool: pointer to the memory pool which was initialized with
143 * mempool_init().
144 *
145 * Free all reserved elements in @pool and @pool itself. This function
146 * only sleeps if the free_fn() function sleeps.
147 *
148 * May be called on a zeroed but uninitialized mempool (i.e. allocated with
149 * kzalloc()).
150 */
151void mempool_exit(mempool_t *pool)
152{
153 while (pool->curr_nr) {
Jia-Ju Bai8cded862018-08-17 15:45:22 -0700154 void *element = remove_element(pool);
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700155 pool->free(element, pool->pool_data);
156 }
157 kfree(pool->elements);
158 pool->elements = NULL;
159}
160EXPORT_SYMBOL(mempool_exit);
161
162/**
Tejun Heo0565d312012-01-10 15:08:26 -0800163 * mempool_destroy - deallocate a memory pool
164 * @pool: pointer to the memory pool which was allocated via
165 * mempool_create().
166 *
167 * Free all reserved elements in @pool and @pool itself. This function
168 * only sleeps if the free_fn() function sleeps.
169 */
170void mempool_destroy(mempool_t *pool)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171{
Sergey Senozhatsky4e3ca3e2015-09-08 15:00:53 -0700172 if (unlikely(!pool))
173 return;
174
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700175 mempool_exit(pool);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 kfree(pool);
177}
Tejun Heo0565d312012-01-10 15:08:26 -0800178EXPORT_SYMBOL(mempool_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700180int mempool_init_node(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
181 mempool_free_t *free_fn, void *pool_data,
182 gfp_t gfp_mask, int node_id)
183{
184 spin_lock_init(&pool->lock);
185 pool->min_nr = min_nr;
186 pool->pool_data = pool_data;
187 pool->alloc = alloc_fn;
188 pool->free = free_fn;
189 init_waitqueue_head(&pool->wait);
190
191 pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
192 gfp_mask, node_id);
193 if (!pool->elements)
194 return -ENOMEM;
195
196 /*
197 * First pre-allocate the guaranteed number of buffers.
198 */
199 while (pool->curr_nr < pool->min_nr) {
200 void *element;
201
202 element = pool->alloc(gfp_mask, pool->pool_data);
203 if (unlikely(!element)) {
204 mempool_exit(pool);
205 return -ENOMEM;
206 }
207 add_element(pool, element);
208 }
209
210 return 0;
211}
212EXPORT_SYMBOL(mempool_init_node);
213
214/**
215 * mempool_init - initialize a memory pool
Mike Rapoporta3bf6ce2018-08-21 21:53:03 -0700216 * @pool: pointer to the memory pool that should be initialized
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700217 * @min_nr: the minimum number of elements guaranteed to be
218 * allocated for this pool.
219 * @alloc_fn: user-defined element-allocation function.
220 * @free_fn: user-defined element-freeing function.
221 * @pool_data: optional private data available to the user-defined functions.
222 *
223 * Like mempool_create(), but initializes the pool in (i.e. embedded in another
224 * structure).
225 */
226int mempool_init(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
227 mempool_free_t *free_fn, void *pool_data)
228{
229 return mempool_init_node(pool, min_nr, alloc_fn, free_fn,
230 pool_data, GFP_KERNEL, NUMA_NO_NODE);
231
232}
233EXPORT_SYMBOL(mempool_init);
234
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235/**
236 * mempool_create - create a memory pool
237 * @min_nr: the minimum number of elements guaranteed to be
238 * allocated for this pool.
239 * @alloc_fn: user-defined element-allocation function.
240 * @free_fn: user-defined element-freeing function.
241 * @pool_data: optional private data available to the user-defined functions.
242 *
243 * this function creates and allocates a guaranteed size, preallocated
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800244 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800246 * functions might sleep - as long as the mempool_alloc() function is not called
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 * from IRQ contexts.
248 */
Christoph Lameter19460892005-06-23 00:08:19 -0700249mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 mempool_free_t *free_fn, void *pool_data)
251{
Tejun Heoa91a5ac2012-06-04 20:40:53 -0700252 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
253 GFP_KERNEL, NUMA_NO_NODE);
Christoph Lameter19460892005-06-23 00:08:19 -0700254}
255EXPORT_SYMBOL(mempool_create);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
Christoph Lameter19460892005-06-23 00:08:19 -0700257mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
Tejun Heoa91a5ac2012-06-04 20:40:53 -0700258 mempool_free_t *free_fn, void *pool_data,
259 gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -0700260{
261 mempool_t *pool;
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700262
Joe Perches7b5219d2013-09-11 14:23:07 -0700263 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 if (!pool)
265 return NULL;
Kent Overstreetc1a67fe2015-05-04 16:52:20 -0700266
267 if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data,
268 gfp_mask, node_id)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 kfree(pool);
270 return NULL;
271 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 return pool;
274}
Christoph Lameter19460892005-06-23 00:08:19 -0700275EXPORT_SYMBOL(mempool_create_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276
277/**
278 * mempool_resize - resize an existing memory pool
279 * @pool: pointer to the memory pool which was allocated via
280 * mempool_create().
281 * @new_min_nr: the new minimum number of elements guaranteed to be
282 * allocated for this pool.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 *
284 * This function shrinks/grows the pool. In the case of growing,
285 * it cannot be guaranteed that the pool will be grown to the new
286 * size immediately, but new mempool_free() calls will refill it.
David Rientjes11d83362015-04-14 15:48:21 -0700287 * This function may sleep.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 *
289 * Note, the caller must guarantee that no mempool_destroy is called
290 * while this function is running. mempool_alloc() & mempool_free()
291 * might be called (eg. from IRQ contexts) while this function executes.
292 */
David Rientjes11d83362015-04-14 15:48:21 -0700293int mempool_resize(mempool_t *pool, int new_min_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294{
295 void *element;
296 void **new_elements;
297 unsigned long flags;
298
299 BUG_ON(new_min_nr <= 0);
David Rientjes11d83362015-04-14 15:48:21 -0700300 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301
302 spin_lock_irqsave(&pool->lock, flags);
303 if (new_min_nr <= pool->min_nr) {
304 while (new_min_nr < pool->curr_nr) {
Jia-Ju Bai8cded862018-08-17 15:45:22 -0700305 element = remove_element(pool);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 spin_unlock_irqrestore(&pool->lock, flags);
307 pool->free(element, pool->pool_data);
308 spin_lock_irqsave(&pool->lock, flags);
309 }
310 pool->min_nr = new_min_nr;
311 goto out_unlock;
312 }
313 spin_unlock_irqrestore(&pool->lock, flags);
314
315 /* Grow the pool */
David Rientjes11d83362015-04-14 15:48:21 -0700316 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
317 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 if (!new_elements)
319 return -ENOMEM;
320
321 spin_lock_irqsave(&pool->lock, flags);
322 if (unlikely(new_min_nr <= pool->min_nr)) {
323 /* Raced, other resize will do our work */
324 spin_unlock_irqrestore(&pool->lock, flags);
325 kfree(new_elements);
326 goto out;
327 }
328 memcpy(new_elements, pool->elements,
329 pool->curr_nr * sizeof(*new_elements));
330 kfree(pool->elements);
331 pool->elements = new_elements;
332 pool->min_nr = new_min_nr;
333
334 while (pool->curr_nr < pool->min_nr) {
335 spin_unlock_irqrestore(&pool->lock, flags);
David Rientjes11d83362015-04-14 15:48:21 -0700336 element = pool->alloc(GFP_KERNEL, pool->pool_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 if (!element)
338 goto out;
339 spin_lock_irqsave(&pool->lock, flags);
340 if (pool->curr_nr < pool->min_nr) {
341 add_element(pool, element);
342 } else {
343 spin_unlock_irqrestore(&pool->lock, flags);
344 pool->free(element, pool->pool_data); /* Raced */
345 goto out;
346 }
347 }
348out_unlock:
349 spin_unlock_irqrestore(&pool->lock, flags);
350out:
351 return 0;
352}
353EXPORT_SYMBOL(mempool_resize);
354
355/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 * mempool_alloc - allocate an element from a specific memory pool
357 * @pool: pointer to the memory pool which was allocated via
358 * mempool_create().
359 * @gfp_mask: the usual allocation bitmask.
360 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800361 * this function only sleeps if the alloc_fn() function sleeps or
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 * returns NULL. Note that due to preallocation, this function
363 * *never* fails when called from process contexts. (it might
364 * fail if called from an IRQ context.)
Michal Hocko4e390b22016-07-28 15:48:44 -0700365 * Note: using __GFP_ZERO is not supported.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 */
David Rientjesf9054c72016-03-17 14:19:19 -0700367void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368{
369 void *element;
370 unsigned long flags;
Ingo Molnarac6424b2017-06-20 12:06:13 +0200371 wait_queue_entry_t wait;
Al Viro6daa0e22005-10-21 03:18:50 -0400372 gfp_t gfp_temp;
Nick Piggin20a77772005-05-01 08:58:37 -0700373
Sebastian Ott8bf8fcb2014-06-04 16:07:00 -0700374 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
Mel Gormand0164ad2015-11-06 16:28:21 -0800375 might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
Nick Pigginb84a35b2005-05-01 08:58:36 -0700376
Michal Hocko4e390b22016-07-28 15:48:44 -0700377 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
Nick Pigginb84a35b2005-05-01 08:58:36 -0700378 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
379 gfp_mask |= __GFP_NOWARN; /* failures are OK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380
Mel Gormand0164ad2015-11-06 16:28:21 -0800381 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
Nick Piggin20a77772005-05-01 08:58:37 -0700382
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383repeat_alloc:
Nick Piggin20a77772005-05-01 08:58:37 -0700384
385 element = pool->alloc(gfp_temp, pool->pool_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 if (likely(element != NULL))
387 return element;
388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 spin_lock_irqsave(&pool->lock, flags);
390 if (likely(pool->curr_nr)) {
Jia-Ju Bai8cded862018-08-17 15:45:22 -0700391 element = remove_element(pool);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 spin_unlock_irqrestore(&pool->lock, flags);
Tejun Heo5b990542012-01-10 15:08:23 -0800393 /* paired with rmb in mempool_free(), read comment there */
394 smp_wmb();
Catalin Marinas17411962014-06-06 14:38:19 -0700395 /*
396 * Update the allocation stack trace as this is more useful
397 * for debugging.
398 */
399 kmemleak_update_trace(element);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 return element;
401 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402
Tejun Heo1ebb7042012-01-10 15:08:28 -0800403 /*
Mel Gormand0164ad2015-11-06 16:28:21 -0800404 * We use gfp mask w/o direct reclaim or IO for the first round. If
Tejun Heo1ebb7042012-01-10 15:08:28 -0800405 * alloc failed with that and @pool was empty, retry immediately.
406 */
Michal Hocko4e390b22016-07-28 15:48:44 -0700407 if (gfp_temp != gfp_mask) {
Tejun Heo1ebb7042012-01-10 15:08:28 -0800408 spin_unlock_irqrestore(&pool->lock, flags);
409 gfp_temp = gfp_mask;
410 goto repeat_alloc;
411 }
412
Mel Gormand0164ad2015-11-06 16:28:21 -0800413 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
414 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
Tejun Heo5b990542012-01-10 15:08:23 -0800415 spin_unlock_irqrestore(&pool->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 return NULL;
Tejun Heo5b990542012-01-10 15:08:23 -0800417 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
Tejun Heo5b990542012-01-10 15:08:23 -0800419 /* Let's wait for someone else to return an element to @pool */
Benjamin LaHaise01890a42005-06-23 00:10:01 -0700420 init_wait(&wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422
Tejun Heo5b990542012-01-10 15:08:23 -0800423 spin_unlock_irqrestore(&pool->lock, flags);
424
425 /*
426 * FIXME: this should be io_schedule(). The timeout is there as a
427 * workaround for some DM problems in 2.6.18.
428 */
429 io_schedule_timeout(5*HZ);
430
431 finish_wait(&pool->wait, &wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 goto repeat_alloc;
433}
434EXPORT_SYMBOL(mempool_alloc);
435
436/**
437 * mempool_free - return an element to the pool.
438 * @element: pool element pointer.
439 * @pool: pointer to the memory pool which was allocated via
440 * mempool_create().
441 *
442 * this function only sleeps if the free_fn() function sleeps.
443 */
444void mempool_free(void *element, mempool_t *pool)
445{
446 unsigned long flags;
447
Rusty Russellc80e7a82007-07-15 23:42:00 -0700448 if (unlikely(element == NULL))
449 return;
450
Tejun Heo5b990542012-01-10 15:08:23 -0800451 /*
452 * Paired with the wmb in mempool_alloc(). The preceding read is
453 * for @element and the following @pool->curr_nr. This ensures
454 * that the visible value of @pool->curr_nr is from after the
455 * allocation of @element. This is necessary for fringe cases
456 * where @element was passed to this task without going through
457 * barriers.
458 *
459 * For example, assume @p is %NULL at the beginning and one task
460 * performs "p = mempool_alloc(...);" while another task is doing
461 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
462 * may end up using curr_nr value which is from before allocation
463 * of @p without the following rmb.
464 */
465 smp_rmb();
466
467 /*
468 * For correctness, we need a test which is guaranteed to trigger
469 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
470 * without locking achieves that and refilling as soon as possible
471 * is desirable.
472 *
473 * Because curr_nr visible here is always a value after the
474 * allocation of @element, any task which decremented curr_nr below
475 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
476 * incremented to min_nr afterwards. If curr_nr gets incremented
477 * to min_nr after the allocation of @element, the elements
478 * allocated after that are subject to the same guarantee.
479 *
480 * Waiters happen iff curr_nr is 0 and the above guarantee also
481 * ensures that there will be frees which return elements to the
482 * pool waking up the waiters.
483 */
Mikulas Patockaeb9a3c62014-04-07 15:37:35 -0700484 if (unlikely(pool->curr_nr < pool->min_nr)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 spin_lock_irqsave(&pool->lock, flags);
Mikulas Patockaeb9a3c62014-04-07 15:37:35 -0700486 if (likely(pool->curr_nr < pool->min_nr)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 add_element(pool, element);
488 spin_unlock_irqrestore(&pool->lock, flags);
489 wake_up(&pool->wait);
490 return;
491 }
492 spin_unlock_irqrestore(&pool->lock, flags);
493 }
494 pool->free(element, pool->pool_data);
495}
496EXPORT_SYMBOL(mempool_free);
497
498/*
499 * A commonly used alloc and free fn.
500 */
Al Virodd0fc662005-10-07 07:46:04 +0100501void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502{
Pekka Enbergfcc234f2006-03-22 00:08:13 -0800503 struct kmem_cache *mem = pool_data;
David Rientjese244c9e2015-04-15 16:14:14 -0700504 VM_BUG_ON(mem->ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 return kmem_cache_alloc(mem, gfp_mask);
506}
507EXPORT_SYMBOL(mempool_alloc_slab);
508
509void mempool_free_slab(void *element, void *pool_data)
510{
Pekka Enbergfcc234f2006-03-22 00:08:13 -0800511 struct kmem_cache *mem = pool_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 kmem_cache_free(mem, element);
513}
514EXPORT_SYMBOL(mempool_free_slab);
Matthew Dobson6e0678f2006-03-26 01:37:44 -0800515
516/*
Matthew Dobson53184082006-03-26 01:37:46 -0800517 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
Simon Arlott183ff222007-10-20 01:27:18 +0200518 * specified by pool_data
Matthew Dobson53184082006-03-26 01:37:46 -0800519 */
520void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
521{
Figo.zhang5e2f89b2009-08-08 21:01:22 +0800522 size_t size = (size_t)pool_data;
Matthew Dobson53184082006-03-26 01:37:46 -0800523 return kmalloc(size, gfp_mask);
524}
525EXPORT_SYMBOL(mempool_kmalloc);
526
527void mempool_kfree(void *element, void *pool_data)
528{
529 kfree(element);
530}
531EXPORT_SYMBOL(mempool_kfree);
532
533/*
Matthew Dobson6e0678f2006-03-26 01:37:44 -0800534 * A simple mempool-backed page allocator that allocates pages
535 * of the order specified by pool_data.
536 */
537void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
538{
539 int order = (int)(long)pool_data;
540 return alloc_pages(gfp_mask, order);
541}
542EXPORT_SYMBOL(mempool_alloc_pages);
543
544void mempool_free_pages(void *element, void *pool_data)
545{
546 int order = (int)(long)pool_data;
547 __free_pages(element, order);
548}
549EXPORT_SYMBOL(mempool_free_pages);