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/module.h>
31#include <linux/mutex.h>
32#include <linux/poison.h>
33#include <linux/sched.h>
34#include <linux/slab.h>
35#include <linux/spinlock.h>
36#include <linux/string.h>
37#include <linux/types.h>
38#include <linux/wait.h>
39
40#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
41#define DMAPOOL_DEBUG 1
42#endif
43
44struct dma_pool { /* the pool */
45    struct list_head page_list;
46    spinlock_t lock;
47    size_t size;
48    struct device *dev;
49    size_t allocation;
50    size_t boundary;
51    char name[32];
52    wait_queue_head_t waitq;
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
64#define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000)
65
66static DEFINE_MUTEX(pools_lock);
67
68static ssize_t
69show_pools(struct device *dev, struct device_attribute *attr, char *buf)
70{
71    unsigned temp;
72    unsigned size;
73    char *next;
74    struct dma_page *page;
75    struct dma_pool *pool;
76
77    next = buf;
78    size = PAGE_SIZE;
79
80    temp = scnprintf(next, size, "poolinfo - 0.1\n");
81    size -= temp;
82    next += temp;
83
84    mutex_lock(&pools_lock);
85    list_for_each_entry(pool, &dev->dma_pools, pools) {
86        unsigned pages = 0;
87        unsigned blocks = 0;
88
89        spin_lock_irq(&pool->lock);
90        list_for_each_entry(page, &pool->page_list, page_list) {
91            pages++;
92            blocks += page->in_use;
93        }
94        spin_unlock_irq(&pool->lock);
95
96        /* per-pool info, no real statistics yet */
97        temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
98                 pool->name, blocks,
99                 pages * (pool->allocation / pool->size),
100                 pool->size, pages);
101        size -= temp;
102        next += temp;
103    }
104    mutex_unlock(&pools_lock);
105
106    return PAGE_SIZE - size;
107}
108
109static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
110
111/**
112 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
113 * @name: name of pool, for diagnostics
114 * @dev: device that will be doing the DMA
115 * @size: size of the blocks in this pool.
116 * @align: alignment requirement for blocks; must be a power of two
117 * @boundary: returned blocks won't cross this power of two boundary
118 * Context: !in_interrupt()
119 *
120 * Returns a dma allocation pool with the requested characteristics, or
121 * null if one can't be created. Given one of these pools, dma_pool_alloc()
122 * may be used to allocate memory. Such memory will all have "consistent"
123 * DMA mappings, accessible by the device and its driver without using
124 * cache flushing primitives. The actual size of blocks allocated may be
125 * larger than requested because of alignment.
126 *
127 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
128 * cross that size boundary. This is useful for devices which have
129 * addressing restrictions on individual DMA transfers, such as not crossing
130 * boundaries of 4KBytes.
131 */
132struct dma_pool *dma_pool_create(const char *name, struct device *dev,
133                 size_t size, size_t align, size_t boundary)
134{
135    struct dma_pool *retval;
136    size_t allocation;
137
138    if (align == 0) {
139        align = 1;
140    } else if (align & (align - 1)) {
141        return NULL;
142    }
143
144    if (size == 0) {
145        return NULL;
146    } else if (size < 4) {
147        size = 4;
148    }
149
150    if ((size % align) != 0)
151        size = ALIGN(size, align);
152
153    allocation = max_t(size_t, size, PAGE_SIZE);
154
155    if (!boundary) {
156        boundary = allocation;
157    } else if ((boundary < size) || (boundary & (boundary - 1))) {
158        return NULL;
159    }
160
161    retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
162    if (!retval)
163        return retval;
164
165    strlcpy(retval->name, name, sizeof(retval->name));
166
167    retval->dev = dev;
168
169    INIT_LIST_HEAD(&retval->page_list);
170    spin_lock_init(&retval->lock);
171    retval->size = size;
172    retval->boundary = boundary;
173    retval->allocation = allocation;
174    init_waitqueue_head(&retval->waitq);
175
176    if (dev) {
177        int ret;
178
179        mutex_lock(&pools_lock);
180        if (list_empty(&dev->dma_pools))
181            ret = device_create_file(dev, &dev_attr_pools);
182        else
183            ret = 0;
184        /* note: not currently insisting "name" be unique */
185        if (!ret)
186            list_add(&retval->pools, &dev->dma_pools);
187        else {
188            kfree(retval);
189            retval = NULL;
190        }
191        mutex_unlock(&pools_lock);
192    } else
193        INIT_LIST_HEAD(&retval->pools);
194
195    return retval;
196}
197EXPORT_SYMBOL(dma_pool_create);
198
199static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
200{
201    unsigned int offset = 0;
202    unsigned int next_boundary = pool->boundary;
203
204    do {
205        unsigned int next = offset + pool->size;
206        if (unlikely((next + pool->size) >= next_boundary)) {
207            next = next_boundary;
208            next_boundary += pool->boundary;
209        }
210        *(int *)(page->vaddr + offset) = next;
211        offset = next;
212    } while (offset < pool->allocation);
213}
214
215static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
216{
217    struct dma_page *page;
218
219    page = kmalloc(sizeof(*page), mem_flags);
220    if (!page)
221        return NULL;
222    page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
223                     &page->dma, mem_flags);
224    if (page->vaddr) {
225#ifdef DMAPOOL_DEBUG
226        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
227#endif
228        pool_initialise_page(pool, page);
229        list_add(&page->page_list, &pool->page_list);
230        page->in_use = 0;
231        page->offset = 0;
232    } else {
233        kfree(page);
234        page = NULL;
235    }
236    return page;
237}
238
239static inline int is_page_busy(struct dma_page *page)
240{
241    return page->in_use != 0;
242}
243
244static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
245{
246    dma_addr_t dma = page->dma;
247
248#ifdef DMAPOOL_DEBUG
249    memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
250#endif
251    dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
252    list_del(&page->page_list);
253    kfree(page);
254}
255
256/**
257 * dma_pool_destroy - destroys a pool of dma memory blocks.
258 * @pool: dma pool that will be destroyed
259 * Context: !in_interrupt()
260 *
261 * Caller guarantees that no more memory from the pool is in use,
262 * and that nothing will try to use the pool after this call.
263 */
264void dma_pool_destroy(struct dma_pool *pool)
265{
266    mutex_lock(&pools_lock);
267    list_del(&pool->pools);
268    if (pool->dev && list_empty(&pool->dev->dma_pools))
269        device_remove_file(pool->dev, &dev_attr_pools);
270    mutex_unlock(&pools_lock);
271
272    while (!list_empty(&pool->page_list)) {
273        struct dma_page *page;
274        page = list_entry(pool->page_list.next,
275                  struct dma_page, page_list);
276        if (is_page_busy(page)) {
277            if (pool->dev)
278                dev_err(pool->dev,
279                    "dma_pool_destroy %s, %p busy\n",
280                    pool->name, page->vaddr);
281            else
282                printk(KERN_ERR
283                       "dma_pool_destroy %s, %p busy\n",
284                       pool->name, page->vaddr);
285            /* leak the still-in-use consistent memory */
286            list_del(&page->page_list);
287            kfree(page);
288        } else
289            pool_free_page(pool, page);
290    }
291
292    kfree(pool);
293}
294EXPORT_SYMBOL(dma_pool_destroy);
295
296/**
297 * dma_pool_alloc - get a block of consistent memory
298 * @pool: dma pool that will produce the block
299 * @mem_flags: GFP_* bitmask
300 * @handle: pointer to dma address of block
301 *
302 * This returns the kernel virtual address of a currently unused block,
303 * and reports its dma address through the handle.
304 * If such a memory block can't be allocated, %NULL is returned.
305 */
306void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
307             dma_addr_t *handle)
308{
309    unsigned long flags;
310    struct dma_page *page;
311    size_t offset;
312    void *retval;
313
314    might_sleep_if(mem_flags & __GFP_WAIT);
315
316    spin_lock_irqsave(&pool->lock, flags);
317 restart:
318    list_for_each_entry(page, &pool->page_list, page_list) {
319        if (page->offset < pool->allocation)
320            goto ready;
321    }
322    page = pool_alloc_page(pool, GFP_ATOMIC);
323    if (!page) {
324        if (mem_flags & __GFP_WAIT) {
325            DECLARE_WAITQUEUE(wait, current);
326
327            __set_current_state(TASK_UNINTERRUPTIBLE);
328            __add_wait_queue(&pool->waitq, &wait);
329            spin_unlock_irqrestore(&pool->lock, flags);
330
331            schedule_timeout(POOL_TIMEOUT_JIFFIES);
332
333            spin_lock_irqsave(&pool->lock, flags);
334            __remove_wait_queue(&pool->waitq, &wait);
335            goto restart;
336        }
337        retval = NULL;
338        goto done;
339    }
340
341 ready:
342    page->in_use++;
343    offset = page->offset;
344    page->offset = *(int *)(page->vaddr + offset);
345    retval = offset + page->vaddr;
346    *handle = offset + page->dma;
347#ifdef DMAPOOL_DEBUG
348    memset(retval, POOL_POISON_ALLOCATED, pool->size);
349#endif
350 done:
351    spin_unlock_irqrestore(&pool->lock, flags);
352    return retval;
353}
354EXPORT_SYMBOL(dma_pool_alloc);
355
356static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
357{
358    struct dma_page *page;
359
360    list_for_each_entry(page, &pool->page_list, page_list) {
361        if (dma < page->dma)
362            continue;
363        if (dma < (page->dma + pool->allocation))
364            return page;
365    }
366    return NULL;
367}
368
369/**
370 * dma_pool_free - put block back into dma pool
371 * @pool: the dma pool holding the block
372 * @vaddr: virtual address of block
373 * @dma: dma address of block
374 *
375 * Caller promises neither device nor driver will again touch this block
376 * unless it is first re-allocated.
377 */
378void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
379{
380    struct dma_page *page;
381    unsigned long flags;
382    unsigned int offset;
383
384    spin_lock_irqsave(&pool->lock, flags);
385    page = pool_find_page(pool, dma);
386    if (!page) {
387        spin_unlock_irqrestore(&pool->lock, flags);
388        if (pool->dev)
389            dev_err(pool->dev,
390                "dma_pool_free %s, %p/%lx (bad dma)\n",
391                pool->name, vaddr, (unsigned long)dma);
392        else
393            printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
394                   pool->name, vaddr, (unsigned long)dma);
395        return;
396    }
397
398    offset = vaddr - page->vaddr;
399#ifdef DMAPOOL_DEBUG
400    if ((dma - page->dma) != offset) {
401        spin_unlock_irqrestore(&pool->lock, flags);
402        if (pool->dev)
403            dev_err(pool->dev,
404                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
405                pool->name, vaddr, (unsigned long long)dma);
406        else
407            printk(KERN_ERR
408                   "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
409                   pool->name, vaddr, (unsigned long long)dma);
410        return;
411    }
412    {
413        unsigned int chain = page->offset;
414        while (chain < pool->allocation) {
415            if (chain != offset) {
416                chain = *(int *)(page->vaddr + chain);
417                continue;
418            }
419            spin_unlock_irqrestore(&pool->lock, flags);
420            if (pool->dev)
421                dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
422                    "already free\n", pool->name,
423                    (unsigned long long)dma);
424            else
425                printk(KERN_ERR "dma_pool_free %s, dma %Lx "
426                    "already free\n", pool->name,
427                    (unsigned long long)dma);
428            return;
429        }
430    }
431    memset(vaddr, POOL_POISON_FREED, pool->size);
432#endif
433
434    page->in_use--;
435    *(int *)vaddr = page->offset;
436    page->offset = offset;
437    if (waitqueue_active(&pool->waitq))
438        wake_up_locked(&pool->waitq);
439    /*
440     * Resist a temptation to do
441     * if (!is_page_busy(page)) pool_free_page(pool, page);
442     * Better have a few empty pages hang around.
443     */
444    spin_unlock_irqrestore(&pool->lock, flags);
445}
446EXPORT_SYMBOL(dma_pool_free);
447
448/*
449 * Managed DMA pool
450 */
451static void dmam_pool_release(struct device *dev, void *res)
452{
453    struct dma_pool *pool = *(struct dma_pool **)res;
454
455    dma_pool_destroy(pool);
456}
457
458static int dmam_pool_match(struct device *dev, void *res, void *match_data)
459{
460    return *(struct dma_pool **)res == match_data;
461}
462
463/**
464 * dmam_pool_create - Managed dma_pool_create()
465 * @name: name of pool, for diagnostics
466 * @dev: device that will be doing the DMA
467 * @size: size of the blocks in this pool.
468 * @align: alignment requirement for blocks; must be a power of two
469 * @allocation: returned blocks won't cross this boundary (or zero)
470 *
471 * Managed dma_pool_create(). DMA pool created with this function is
472 * automatically destroyed on driver detach.
473 */
474struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
475                  size_t size, size_t align, size_t allocation)
476{
477    struct dma_pool **ptr, *pool;
478
479    ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
480    if (!ptr)
481        return NULL;
482
483    pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
484    if (pool)
485        devres_add(dev, ptr);
486    else
487        devres_free(ptr);
488
489    return pool;
490}
491EXPORT_SYMBOL(dmam_pool_create);
492
493/**
494 * dmam_pool_destroy - Managed dma_pool_destroy()
495 * @pool: dma pool that will be destroyed
496 *
497 * Managed dma_pool_destroy().
498 */
499void dmam_pool_destroy(struct dma_pool *pool)
500{
501    struct device *dev = pool->dev;
502
503    dma_pool_destroy(pool);
504    WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
505}
506EXPORT_SYMBOL(dmam_pool_destroy);
507

Archive Download this file



interactive