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TOMOYO Linux Cross Reference
Linux/mm/dmapool.c

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  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 
 45 struct 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 
 56 struct 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 static DEFINE_MUTEX(pools_lock);
 65 static DEFINE_MUTEX(pools_reg_lock);
 66 
 67 static ssize_t
 68 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
 69 {
 70         unsigned temp;
 71         unsigned size;
 72         char *next;
 73         struct dma_page *page;
 74         struct dma_pool *pool;
 75 
 76         next = buf;
 77         size = PAGE_SIZE;
 78 
 79         temp = scnprintf(next, size, "poolinfo - 0.1\n");
 80         size -= temp;
 81         next += temp;
 82 
 83         mutex_lock(&pools_lock);
 84         list_for_each_entry(pool, &dev->dma_pools, pools) {
 85                 unsigned pages = 0;
 86                 unsigned blocks = 0;
 87 
 88                 spin_lock_irq(&pool->lock);
 89                 list_for_each_entry(page, &pool->page_list, page_list) {
 90                         pages++;
 91                         blocks += page->in_use;
 92                 }
 93                 spin_unlock_irq(&pool->lock);
 94 
 95                 /* per-pool info, no real statistics yet */
 96                 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
 97                                  pool->name, blocks,
 98                                  pages * (pool->allocation / pool->size),
 99                                  pool->size, pages);
100                 size -= temp;
101                 next += temp;
102         }
103         mutex_unlock(&pools_lock);
104 
105         return PAGE_SIZE - size;
106 }
107 
108 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
109 
110 /**
111  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
112  * @name: name of pool, for diagnostics
113  * @dev: device that will be doing the DMA
114  * @size: size of the blocks in this pool.
115  * @align: alignment requirement for blocks; must be a power of two
116  * @boundary: returned blocks won't cross this power of two boundary
117  * Context: !in_interrupt()
118  *
119  * Returns a dma allocation pool with the requested characteristics, or
120  * null if one can't be created.  Given one of these pools, dma_pool_alloc()
121  * may be used to allocate memory.  Such memory will all have "consistent"
122  * DMA mappings, accessible by the device and its driver without using
123  * cache flushing primitives.  The actual size of blocks allocated may be
124  * larger than requested because of alignment.
125  *
126  * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
127  * cross that size boundary.  This is useful for devices which have
128  * addressing restrictions on individual DMA transfers, such as not crossing
129  * boundaries of 4KBytes.
130  */
131 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
132                                  size_t size, size_t align, size_t boundary)
133 {
134         struct dma_pool *retval;
135         size_t allocation;
136         bool empty = false;
137 
138         if (align == 0)
139                 align = 1;
140         else if (align & (align - 1))
141                 return NULL;
142 
143         if (size == 0)
144                 return NULL;
145         else if (size < 4)
146                 size = 4;
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         retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
159         if (!retval)
160                 return retval;
161 
162         strlcpy(retval->name, name, sizeof(retval->name));
163 
164         retval->dev = dev;
165 
166         INIT_LIST_HEAD(&retval->page_list);
167         spin_lock_init(&retval->lock);
168         retval->size = size;
169         retval->boundary = boundary;
170         retval->allocation = allocation;
171 
172         INIT_LIST_HEAD(&retval->pools);
173 
174         /*
175          * pools_lock ensures that the ->dma_pools list does not get corrupted.
176          * pools_reg_lock ensures that there is not a race between
177          * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
178          * when the first invocation of dma_pool_create() failed on
179          * device_create_file() and the second assumes that it has been done (I
180          * know it is a short window).
181          */
182         mutex_lock(&pools_reg_lock);
183         mutex_lock(&pools_lock);
184         if (list_empty(&dev->dma_pools))
185                 empty = true;
186         list_add(&retval->pools, &dev->dma_pools);
187         mutex_unlock(&pools_lock);
188         if (empty) {
189                 int err;
190 
191                 err = device_create_file(dev, &dev_attr_pools);
192                 if (err) {
193                         mutex_lock(&pools_lock);
194                         list_del(&retval->pools);
195                         mutex_unlock(&pools_lock);
196                         mutex_unlock(&pools_reg_lock);
197                         kfree(retval);
198                         return NULL;
199                 }
200         }
201         mutex_unlock(&pools_reg_lock);
202         return retval;
203 }
204 EXPORT_SYMBOL(dma_pool_create);
205 
206 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
207 {
208         unsigned int offset = 0;
209         unsigned int next_boundary = pool->boundary;
210 
211         do {
212                 unsigned int next = offset + pool->size;
213                 if (unlikely((next + pool->size) >= next_boundary)) {
214                         next = next_boundary;
215                         next_boundary += pool->boundary;
216                 }
217                 *(int *)(page->vaddr + offset) = next;
218                 offset = next;
219         } while (offset < pool->allocation);
220 }
221 
222 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
223 {
224         struct dma_page *page;
225 
226         page = kmalloc(sizeof(*page), mem_flags);
227         if (!page)
228                 return NULL;
229         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
230                                          &page->dma, mem_flags);
231         if (page->vaddr) {
232 #ifdef  DMAPOOL_DEBUG
233                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
234 #endif
235                 pool_initialise_page(pool, page);
236                 page->in_use = 0;
237                 page->offset = 0;
238         } else {
239                 kfree(page);
240                 page = NULL;
241         }
242         return page;
243 }
244 
245 static inline int is_page_busy(struct dma_page *page)
246 {
247         return page->in_use != 0;
248 }
249 
250 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
251 {
252         dma_addr_t dma = page->dma;
253 
254 #ifdef  DMAPOOL_DEBUG
255         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
256 #endif
257         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
258         list_del(&page->page_list);
259         kfree(page);
260 }
261 
262 /**
263  * dma_pool_destroy - destroys a pool of dma memory blocks.
264  * @pool: dma pool that will be destroyed
265  * Context: !in_interrupt()
266  *
267  * Caller guarantees that no more memory from the pool is in use,
268  * and that nothing will try to use the pool after this call.
269  */
270 void dma_pool_destroy(struct dma_pool *pool)
271 {
272         bool empty = false;
273 
274         mutex_lock(&pools_reg_lock);
275         mutex_lock(&pools_lock);
276         list_del(&pool->pools);
277         if (pool->dev && list_empty(&pool->dev->dma_pools))
278                 empty = true;
279         mutex_unlock(&pools_lock);
280         if (empty)
281                 device_remove_file(pool->dev, &dev_attr_pools);
282         mutex_unlock(&pools_reg_lock);
283 
284         while (!list_empty(&pool->page_list)) {
285                 struct dma_page *page;
286                 page = list_entry(pool->page_list.next,
287                                   struct dma_page, page_list);
288                 if (is_page_busy(page)) {
289                         if (pool->dev)
290                                 dev_err(pool->dev,
291                                         "dma_pool_destroy %s, %p busy\n",
292                                         pool->name, page->vaddr);
293                         else
294                                 printk(KERN_ERR
295                                        "dma_pool_destroy %s, %p busy\n",
296                                        pool->name, page->vaddr);
297                         /* leak the still-in-use consistent memory */
298                         list_del(&page->page_list);
299                         kfree(page);
300                 } else
301                         pool_free_page(pool, page);
302         }
303 
304         kfree(pool);
305 }
306 EXPORT_SYMBOL(dma_pool_destroy);
307 
308 /**
309  * dma_pool_alloc - get a block of consistent memory
310  * @pool: dma pool that will produce the block
311  * @mem_flags: GFP_* bitmask
312  * @handle: pointer to dma address of block
313  *
314  * This returns the kernel virtual address of a currently unused block,
315  * and reports its dma address through the handle.
316  * If such a memory block can't be allocated, %NULL is returned.
317  */
318 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
319                      dma_addr_t *handle)
320 {
321         unsigned long flags;
322         struct dma_page *page;
323         size_t offset;
324         void *retval;
325 
326         might_sleep_if(mem_flags & __GFP_WAIT);
327 
328         spin_lock_irqsave(&pool->lock, flags);
329         list_for_each_entry(page, &pool->page_list, page_list) {
330                 if (page->offset < pool->allocation)
331                         goto ready;
332         }
333 
334         /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
335         spin_unlock_irqrestore(&pool->lock, flags);
336 
337         page = pool_alloc_page(pool, mem_flags);
338         if (!page)
339                 return NULL;
340 
341         spin_lock_irqsave(&pool->lock, flags);
342 
343         list_add(&page->page_list, &pool->page_list);
344  ready:
345         page->in_use++;
346         offset = page->offset;
347         page->offset = *(int *)(page->vaddr + offset);
348         retval = offset + page->vaddr;
349         *handle = offset + page->dma;
350 #ifdef  DMAPOOL_DEBUG
351         {
352                 int i;
353                 u8 *data = retval;
354                 /* page->offset is stored in first 4 bytes */
355                 for (i = sizeof(page->offset); i < pool->size; i++) {
356                         if (data[i] == POOL_POISON_FREED)
357                                 continue;
358                         if (pool->dev)
359                                 dev_err(pool->dev,
360                                         "dma_pool_alloc %s, %p (corrupted)\n",
361                                         pool->name, retval);
362                         else
363                                 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
364                                         pool->name, retval);
365 
366                         /*
367                          * Dump the first 4 bytes even if they are not
368                          * POOL_POISON_FREED
369                          */
370                         print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
371                                         data, pool->size, 1);
372                         break;
373                 }
374         }
375         memset(retval, POOL_POISON_ALLOCATED, pool->size);
376 #endif
377         spin_unlock_irqrestore(&pool->lock, flags);
378         return retval;
379 }
380 EXPORT_SYMBOL(dma_pool_alloc);
381 
382 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
383 {
384         struct dma_page *page;
385 
386         list_for_each_entry(page, &pool->page_list, page_list) {
387                 if (dma < page->dma)
388                         continue;
389                 if (dma < (page->dma + pool->allocation))
390                         return page;
391         }
392         return NULL;
393 }
394 
395 /**
396  * dma_pool_free - put block back into dma pool
397  * @pool: the dma pool holding the block
398  * @vaddr: virtual address of block
399  * @dma: dma address of block
400  *
401  * Caller promises neither device nor driver will again touch this block
402  * unless it is first re-allocated.
403  */
404 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
405 {
406         struct dma_page *page;
407         unsigned long flags;
408         unsigned int offset;
409 
410         spin_lock_irqsave(&pool->lock, flags);
411         page = pool_find_page(pool, dma);
412         if (!page) {
413                 spin_unlock_irqrestore(&pool->lock, flags);
414                 if (pool->dev)
415                         dev_err(pool->dev,
416                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
417                                 pool->name, vaddr, (unsigned long)dma);
418                 else
419                         printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
420                                pool->name, vaddr, (unsigned long)dma);
421                 return;
422         }
423 
424         offset = vaddr - page->vaddr;
425 #ifdef  DMAPOOL_DEBUG
426         if ((dma - page->dma) != offset) {
427                 spin_unlock_irqrestore(&pool->lock, flags);
428                 if (pool->dev)
429                         dev_err(pool->dev,
430                                 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
431                                 pool->name, vaddr, (unsigned long long)dma);
432                 else
433                         printk(KERN_ERR
434                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
435                                pool->name, vaddr, (unsigned long long)dma);
436                 return;
437         }
438         {
439                 unsigned int chain = page->offset;
440                 while (chain < pool->allocation) {
441                         if (chain != offset) {
442                                 chain = *(int *)(page->vaddr + chain);
443                                 continue;
444                         }
445                         spin_unlock_irqrestore(&pool->lock, flags);
446                         if (pool->dev)
447                                 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
448                                         "already free\n", pool->name,
449                                         (unsigned long long)dma);
450                         else
451                                 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
452                                         "already free\n", pool->name,
453                                         (unsigned long long)dma);
454                         return;
455                 }
456         }
457         memset(vaddr, POOL_POISON_FREED, pool->size);
458 #endif
459 
460         page->in_use--;
461         *(int *)vaddr = page->offset;
462         page->offset = offset;
463         /*
464          * Resist a temptation to do
465          *    if (!is_page_busy(page)) pool_free_page(pool, page);
466          * Better have a few empty pages hang around.
467          */
468         spin_unlock_irqrestore(&pool->lock, flags);
469 }
470 EXPORT_SYMBOL(dma_pool_free);
471 
472 /*
473  * Managed DMA pool
474  */
475 static void dmam_pool_release(struct device *dev, void *res)
476 {
477         struct dma_pool *pool = *(struct dma_pool **)res;
478 
479         dma_pool_destroy(pool);
480 }
481 
482 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
483 {
484         return *(struct dma_pool **)res == match_data;
485 }
486 
487 /**
488  * dmam_pool_create - Managed dma_pool_create()
489  * @name: name of pool, for diagnostics
490  * @dev: device that will be doing the DMA
491  * @size: size of the blocks in this pool.
492  * @align: alignment requirement for blocks; must be a power of two
493  * @allocation: returned blocks won't cross this boundary (or zero)
494  *
495  * Managed dma_pool_create().  DMA pool created with this function is
496  * automatically destroyed on driver detach.
497  */
498 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
499                                   size_t size, size_t align, size_t allocation)
500 {
501         struct dma_pool **ptr, *pool;
502 
503         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
504         if (!ptr)
505                 return NULL;
506 
507         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
508         if (pool)
509                 devres_add(dev, ptr);
510         else
511                 devres_free(ptr);
512 
513         return pool;
514 }
515 EXPORT_SYMBOL(dmam_pool_create);
516 
517 /**
518  * dmam_pool_destroy - Managed dma_pool_destroy()
519  * @pool: dma pool that will be destroyed
520  *
521  * Managed dma_pool_destroy().
522  */
523 void dmam_pool_destroy(struct dma_pool *pool)
524 {
525         struct device *dev = pool->dev;
526 
527         WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
528 }
529 EXPORT_SYMBOL(dmam_pool_destroy);
530 

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