Root/mm/dmapool.c

1/*
2 * DMA Pool allocator
3 *
4 * Copyright 2001 David Brownell
5 * Copyright 2007 Intel Corporation
6 * Author: Matthew Wilcox <willy@linux.intel.com>
7 *
8 * This software may be redistributed and/or modified under the terms of
9 * the GNU General Public License ("GPL") version 2 as published by the
10 * Free Software Foundation.
11 *
12 * This allocator returns small blocks of a given size which are DMA-able by
13 * the given device. It uses the dma_alloc_coherent page allocator to get
14 * new pages, then splits them up into blocks of the required size.
15 * Many older drivers still have their own code to do this.
16 *
17 * The current design of this allocator is fairly simple. The pool is
18 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
19 * allocated pages. Each page in the page_list is split into blocks of at
20 * least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
21 * list of free blocks within the page. Used blocks aren't tracked, but we
22 * keep a count of how many are currently allocated from each page.
23 */
24
25#include <linux/device.h>
26#include <linux/dma-mapping.h>
27#include <linux/dmapool.h>
28#include <linux/kernel.h>
29#include <linux/list.h>
30#include <linux/export.h>
31#include <linux/mutex.h>
32#include <linux/poison.h>
33#include <linux/sched.h>
34#include <linux/slab.h>
35#include <linux/stat.h>
36#include <linux/spinlock.h>
37#include <linux/string.h>
38#include <linux/types.h>
39#include <linux/wait.h>
40
41#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
42#define DMAPOOL_DEBUG 1
43#endif
44
45struct dma_pool { /* the pool */
46    struct list_head page_list;
47    spinlock_t lock;
48    size_t size;
49    struct device *dev;
50    size_t allocation;
51    size_t boundary;
52    char name[32];
53    struct list_head pools;
54};
55
56struct dma_page { /* cacheable header for 'allocation' bytes */
57    struct list_head page_list;
58    void *vaddr;
59    dma_addr_t dma;
60    unsigned int in_use;
61    unsigned int offset;
62};
63
64static DEFINE_MUTEX(pools_lock);
65
66static ssize_t
67show_pools(struct device *dev, struct device_attribute *attr, char *buf)
68{
69    unsigned temp;
70    unsigned size;
71    char *next;
72    struct dma_page *page;
73    struct dma_pool *pool;
74
75    next = buf;
76    size = PAGE_SIZE;
77
78    temp = scnprintf(next, size, "poolinfo - 0.1\n");
79    size -= temp;
80    next += temp;
81
82    mutex_lock(&pools_lock);
83    list_for_each_entry(pool, &dev->dma_pools, pools) {
84        unsigned pages = 0;
85        unsigned blocks = 0;
86
87        spin_lock_irq(&pool->lock);
88        list_for_each_entry(page, &pool->page_list, page_list) {
89            pages++;
90            blocks += page->in_use;
91        }
92        spin_unlock_irq(&pool->lock);
93
94        /* per-pool info, no real statistics yet */
95        temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
96                 pool->name, blocks,
97                 pages * (pool->allocation / pool->size),
98                 pool->size, pages);
99        size -= temp;
100        next += temp;
101    }
102    mutex_unlock(&pools_lock);
103
104    return PAGE_SIZE - size;
105}
106
107static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
108
109/**
110 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
111 * @name: name of pool, for diagnostics
112 * @dev: device that will be doing the DMA
113 * @size: size of the blocks in this pool.
114 * @align: alignment requirement for blocks; must be a power of two
115 * @boundary: returned blocks won't cross this power of two boundary
116 * Context: !in_interrupt()
117 *
118 * Returns a dma allocation pool with the requested characteristics, or
119 * null if one can't be created. Given one of these pools, dma_pool_alloc()
120 * may be used to allocate memory. Such memory will all have "consistent"
121 * DMA mappings, accessible by the device and its driver without using
122 * cache flushing primitives. The actual size of blocks allocated may be
123 * larger than requested because of alignment.
124 *
125 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
126 * cross that size boundary. This is useful for devices which have
127 * addressing restrictions on individual DMA transfers, such as not crossing
128 * boundaries of 4KBytes.
129 */
130struct dma_pool *dma_pool_create(const char *name, struct device *dev,
131                 size_t size, size_t align, size_t boundary)
132{
133    struct dma_pool *retval;
134    size_t allocation;
135
136    if (align == 0) {
137        align = 1;
138    } else if (align & (align - 1)) {
139        return NULL;
140    }
141
142    if (size == 0) {
143        return NULL;
144    } else if (size < 4) {
145        size = 4;
146    }
147
148    if ((size % align) != 0)
149        size = ALIGN(size, align);
150
151    allocation = max_t(size_t, size, PAGE_SIZE);
152
153    if (!boundary) {
154        boundary = allocation;
155    } else if ((boundary < size) || (boundary & (boundary - 1))) {
156        return NULL;
157    }
158
159    retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
160    if (!retval)
161        return retval;
162
163    strlcpy(retval->name, name, sizeof(retval->name));
164
165    retval->dev = dev;
166
167    INIT_LIST_HEAD(&retval->page_list);
168    spin_lock_init(&retval->lock);
169    retval->size = size;
170    retval->boundary = boundary;
171    retval->allocation = allocation;
172
173    if (dev) {
174        int ret;
175
176        mutex_lock(&pools_lock);
177        if (list_empty(&dev->dma_pools))
178            ret = device_create_file(dev, &dev_attr_pools);
179        else
180            ret = 0;
181        /* note: not currently insisting "name" be unique */
182        if (!ret)
183            list_add(&retval->pools, &dev->dma_pools);
184        else {
185            kfree(retval);
186            retval = NULL;
187        }
188        mutex_unlock(&pools_lock);
189    } else
190        INIT_LIST_HEAD(&retval->pools);
191
192    return retval;
193}
194EXPORT_SYMBOL(dma_pool_create);
195
196static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
197{
198    unsigned int offset = 0;
199    unsigned int next_boundary = pool->boundary;
200
201    do {
202        unsigned int next = offset + pool->size;
203        if (unlikely((next + pool->size) >= next_boundary)) {
204            next = next_boundary;
205            next_boundary += pool->boundary;
206        }
207        *(int *)(page->vaddr + offset) = next;
208        offset = next;
209    } while (offset < pool->allocation);
210}
211
212static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
213{
214    struct dma_page *page;
215
216    page = kmalloc(sizeof(*page), mem_flags);
217    if (!page)
218        return NULL;
219    page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
220                     &page->dma, mem_flags);
221    if (page->vaddr) {
222#ifdef DMAPOOL_DEBUG
223        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
224#endif
225        pool_initialise_page(pool, page);
226        page->in_use = 0;
227        page->offset = 0;
228    } else {
229        kfree(page);
230        page = NULL;
231    }
232    return page;
233}
234
235static inline int is_page_busy(struct dma_page *page)
236{
237    return page->in_use != 0;
238}
239
240static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
241{
242    dma_addr_t dma = page->dma;
243
244#ifdef DMAPOOL_DEBUG
245    memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
246#endif
247    dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
248    list_del(&page->page_list);
249    kfree(page);
250}
251
252/**
253 * dma_pool_destroy - destroys a pool of dma memory blocks.
254 * @pool: dma pool that will be destroyed
255 * Context: !in_interrupt()
256 *
257 * Caller guarantees that no more memory from the pool is in use,
258 * and that nothing will try to use the pool after this call.
259 */
260void dma_pool_destroy(struct dma_pool *pool)
261{
262    mutex_lock(&pools_lock);
263    list_del(&pool->pools);
264    if (pool->dev && list_empty(&pool->dev->dma_pools))
265        device_remove_file(pool->dev, &dev_attr_pools);
266    mutex_unlock(&pools_lock);
267
268    while (!list_empty(&pool->page_list)) {
269        struct dma_page *page;
270        page = list_entry(pool->page_list.next,
271                  struct dma_page, page_list);
272        if (is_page_busy(page)) {
273            if (pool->dev)
274                dev_err(pool->dev,
275                    "dma_pool_destroy %s, %p busy\n",
276                    pool->name, page->vaddr);
277            else
278                printk(KERN_ERR
279                       "dma_pool_destroy %s, %p busy\n",
280                       pool->name, page->vaddr);
281            /* leak the still-in-use consistent memory */
282            list_del(&page->page_list);
283            kfree(page);
284        } else
285            pool_free_page(pool, page);
286    }
287
288    kfree(pool);
289}
290EXPORT_SYMBOL(dma_pool_destroy);
291
292/**
293 * dma_pool_alloc - get a block of consistent memory
294 * @pool: dma pool that will produce the block
295 * @mem_flags: GFP_* bitmask
296 * @handle: pointer to dma address of block
297 *
298 * This returns the kernel virtual address of a currently unused block,
299 * and reports its dma address through the handle.
300 * If such a memory block can't be allocated, %NULL is returned.
301 */
302void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
303             dma_addr_t *handle)
304{
305    unsigned long flags;
306    struct dma_page *page;
307    size_t offset;
308    void *retval;
309
310    might_sleep_if(mem_flags & __GFP_WAIT);
311
312    spin_lock_irqsave(&pool->lock, flags);
313    list_for_each_entry(page, &pool->page_list, page_list) {
314        if (page->offset < pool->allocation)
315            goto ready;
316    }
317
318    /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
319    spin_unlock_irqrestore(&pool->lock, flags);
320
321    page = pool_alloc_page(pool, mem_flags);
322    if (!page)
323        return NULL;
324
325    spin_lock_irqsave(&pool->lock, flags);
326
327    list_add(&page->page_list, &pool->page_list);
328 ready:
329    page->in_use++;
330    offset = page->offset;
331    page->offset = *(int *)(page->vaddr + offset);
332    retval = offset + page->vaddr;
333    *handle = offset + page->dma;
334#ifdef DMAPOOL_DEBUG
335    {
336        int i;
337        u8 *data = retval;
338        /* page->offset is stored in first 4 bytes */
339        for (i = sizeof(page->offset); i < pool->size; i++) {
340            if (data[i] == POOL_POISON_FREED)
341                continue;
342            if (pool->dev)
343                dev_err(pool->dev,
344                    "dma_pool_alloc %s, %p (corruped)\n",
345                    pool->name, retval);
346            else
347                pr_err("dma_pool_alloc %s, %p (corruped)\n",
348                    pool->name, retval);
349
350            /*
351             * Dump the first 4 bytes even if they are not
352             * POOL_POISON_FREED
353             */
354            print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
355                    data, pool->size, 1);
356            break;
357        }
358    }
359    memset(retval, POOL_POISON_ALLOCATED, pool->size);
360#endif
361    spin_unlock_irqrestore(&pool->lock, flags);
362    return retval;
363}
364EXPORT_SYMBOL(dma_pool_alloc);
365
366static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
367{
368    struct dma_page *page;
369
370    list_for_each_entry(page, &pool->page_list, page_list) {
371        if (dma < page->dma)
372            continue;
373        if (dma < (page->dma + pool->allocation))
374            return page;
375    }
376    return NULL;
377}
378
379/**
380 * dma_pool_free - put block back into dma pool
381 * @pool: the dma pool holding the block
382 * @vaddr: virtual address of block
383 * @dma: dma address of block
384 *
385 * Caller promises neither device nor driver will again touch this block
386 * unless it is first re-allocated.
387 */
388void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
389{
390    struct dma_page *page;
391    unsigned long flags;
392    unsigned int offset;
393
394    spin_lock_irqsave(&pool->lock, flags);
395    page = pool_find_page(pool, dma);
396    if (!page) {
397        spin_unlock_irqrestore(&pool->lock, flags);
398        if (pool->dev)
399            dev_err(pool->dev,
400                "dma_pool_free %s, %p/%lx (bad dma)\n",
401                pool->name, vaddr, (unsigned long)dma);
402        else
403            printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
404                   pool->name, vaddr, (unsigned long)dma);
405        return;
406    }
407
408    offset = vaddr - page->vaddr;
409#ifdef DMAPOOL_DEBUG
410    if ((dma - page->dma) != offset) {
411        spin_unlock_irqrestore(&pool->lock, flags);
412        if (pool->dev)
413            dev_err(pool->dev,
414                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
415                pool->name, vaddr, (unsigned long long)dma);
416        else
417            printk(KERN_ERR
418                   "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
419                   pool->name, vaddr, (unsigned long long)dma);
420        return;
421    }
422    {
423        unsigned int chain = page->offset;
424        while (chain < pool->allocation) {
425            if (chain != offset) {
426                chain = *(int *)(page->vaddr + chain);
427                continue;
428            }
429            spin_unlock_irqrestore(&pool->lock, flags);
430            if (pool->dev)
431                dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
432                    "already free\n", pool->name,
433                    (unsigned long long)dma);
434            else
435                printk(KERN_ERR "dma_pool_free %s, dma %Lx "
436                    "already free\n", pool->name,
437                    (unsigned long long)dma);
438            return;
439        }
440    }
441    memset(vaddr, POOL_POISON_FREED, pool->size);
442#endif
443
444    page->in_use--;
445    *(int *)vaddr = page->offset;
446    page->offset = offset;
447    /*
448     * Resist a temptation to do
449     * if (!is_page_busy(page)) pool_free_page(pool, page);
450     * Better have a few empty pages hang around.
451     */
452    spin_unlock_irqrestore(&pool->lock, flags);
453}
454EXPORT_SYMBOL(dma_pool_free);
455
456/*
457 * Managed DMA pool
458 */
459static void dmam_pool_release(struct device *dev, void *res)
460{
461    struct dma_pool *pool = *(struct dma_pool **)res;
462
463    dma_pool_destroy(pool);
464}
465
466static int dmam_pool_match(struct device *dev, void *res, void *match_data)
467{
468    return *(struct dma_pool **)res == match_data;
469}
470
471/**
472 * dmam_pool_create - Managed dma_pool_create()
473 * @name: name of pool, for diagnostics
474 * @dev: device that will be doing the DMA
475 * @size: size of the blocks in this pool.
476 * @align: alignment requirement for blocks; must be a power of two
477 * @allocation: returned blocks won't cross this boundary (or zero)
478 *
479 * Managed dma_pool_create(). DMA pool created with this function is
480 * automatically destroyed on driver detach.
481 */
482struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
483                  size_t size, size_t align, size_t allocation)
484{
485    struct dma_pool **ptr, *pool;
486
487    ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
488    if (!ptr)
489        return NULL;
490
491    pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
492    if (pool)
493        devres_add(dev, ptr);
494    else
495        devres_free(ptr);
496
497    return pool;
498}
499EXPORT_SYMBOL(dmam_pool_create);
500
501/**
502 * dmam_pool_destroy - Managed dma_pool_destroy()
503 * @pool: dma pool that will be destroyed
504 *
505 * Managed dma_pool_destroy().
506 */
507void dmam_pool_destroy(struct dma_pool *pool)
508{
509    struct device *dev = pool->dev;
510
511    WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
512    dma_pool_destroy(pool);
513}
514EXPORT_SYMBOL(dmam_pool_destroy);
515

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