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Linux/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 
 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 bool 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         if (unlikely(!pool))
275                 return;
276 
277         mutex_lock(&pools_reg_lock);
278         mutex_lock(&pools_lock);
279         list_del(&pool->pools);
280         if (pool->dev && list_empty(&pool->dev->dma_pools))
281                 empty = true;
282         mutex_unlock(&pools_lock);
283         if (empty)
284                 device_remove_file(pool->dev, &dev_attr_pools);
285         mutex_unlock(&pools_reg_lock);
286 
287         while (!list_empty(&pool->page_list)) {
288                 struct dma_page *page;
289                 page = list_entry(pool->page_list.next,
290                                   struct dma_page, page_list);
291                 if (is_page_busy(page)) {
292                         if (pool->dev)
293                                 dev_err(pool->dev,
294                                         "dma_pool_destroy %s, %p busy\n",
295                                         pool->name, page->vaddr);
296                         else
297                                 pr_err("dma_pool_destroy %s, %p busy\n",
298                                        pool->name, page->vaddr);
299                         /* leak the still-in-use consistent memory */
300                         list_del(&page->page_list);
301                         kfree(page);
302                 } else
303                         pool_free_page(pool, page);
304         }
305 
306         kfree(pool);
307 }
308 EXPORT_SYMBOL(dma_pool_destroy);
309 
310 /**
311  * dma_pool_alloc - get a block of consistent memory
312  * @pool: dma pool that will produce the block
313  * @mem_flags: GFP_* bitmask
314  * @handle: pointer to dma address of block
315  *
316  * This returns the kernel virtual address of a currently unused block,
317  * and reports its dma address through the handle.
318  * If such a memory block can't be allocated, %NULL is returned.
319  */
320 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
321                      dma_addr_t *handle)
322 {
323         unsigned long flags;
324         struct dma_page *page;
325         size_t offset;
326         void *retval;
327 
328         might_sleep_if(gfpflags_allow_blocking(mem_flags));
329 
330         spin_lock_irqsave(&pool->lock, flags);
331         list_for_each_entry(page, &pool->page_list, page_list) {
332                 if (page->offset < pool->allocation)
333                         goto ready;
334         }
335 
336         /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
337         spin_unlock_irqrestore(&pool->lock, flags);
338 
339         page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
340         if (!page)
341                 return NULL;
342 
343         spin_lock_irqsave(&pool->lock, flags);
344 
345         list_add(&page->page_list, &pool->page_list);
346  ready:
347         page->in_use++;
348         offset = page->offset;
349         page->offset = *(int *)(page->vaddr + offset);
350         retval = offset + page->vaddr;
351         *handle = offset + page->dma;
352 #ifdef  DMAPOOL_DEBUG
353         {
354                 int i;
355                 u8 *data = retval;
356                 /* page->offset is stored in first 4 bytes */
357                 for (i = sizeof(page->offset); i < pool->size; i++) {
358                         if (data[i] == POOL_POISON_FREED)
359                                 continue;
360                         if (pool->dev)
361                                 dev_err(pool->dev,
362                                         "dma_pool_alloc %s, %p (corrupted)\n",
363                                         pool->name, retval);
364                         else
365                                 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
366                                         pool->name, retval);
367 
368                         /*
369                          * Dump the first 4 bytes even if they are not
370                          * POOL_POISON_FREED
371                          */
372                         print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
373                                         data, pool->size, 1);
374                         break;
375                 }
376         }
377         if (!(mem_flags & __GFP_ZERO))
378                 memset(retval, POOL_POISON_ALLOCATED, pool->size);
379 #endif
380         spin_unlock_irqrestore(&pool->lock, flags);
381 
382         if (mem_flags & __GFP_ZERO)
383                 memset(retval, 0, pool->size);
384 
385         return retval;
386 }
387 EXPORT_SYMBOL(dma_pool_alloc);
388 
389 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
390 {
391         struct dma_page *page;
392 
393         list_for_each_entry(page, &pool->page_list, page_list) {
394                 if (dma < page->dma)
395                         continue;
396                 if ((dma - page->dma) < pool->allocation)
397                         return page;
398         }
399         return NULL;
400 }
401 
402 /**
403  * dma_pool_free - put block back into dma pool
404  * @pool: the dma pool holding the block
405  * @vaddr: virtual address of block
406  * @dma: dma address of block
407  *
408  * Caller promises neither device nor driver will again touch this block
409  * unless it is first re-allocated.
410  */
411 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
412 {
413         struct dma_page *page;
414         unsigned long flags;
415         unsigned int offset;
416 
417         spin_lock_irqsave(&pool->lock, flags);
418         page = pool_find_page(pool, dma);
419         if (!page) {
420                 spin_unlock_irqrestore(&pool->lock, flags);
421                 if (pool->dev)
422                         dev_err(pool->dev,
423                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
424                                 pool->name, vaddr, (unsigned long)dma);
425                 else
426                         pr_err("dma_pool_free %s, %p/%lx (bad dma)\n",
427                                pool->name, vaddr, (unsigned long)dma);
428                 return;
429         }
430 
431         offset = vaddr - page->vaddr;
432 #ifdef  DMAPOOL_DEBUG
433         if ((dma - page->dma) != offset) {
434                 spin_unlock_irqrestore(&pool->lock, flags);
435                 if (pool->dev)
436                         dev_err(pool->dev,
437                                 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
438                                 pool->name, vaddr, (unsigned long long)dma);
439                 else
440                         pr_err("dma_pool_free %s, %p (bad vaddr)/%Lx\n",
441                                pool->name, vaddr, (unsigned long long)dma);
442                 return;
443         }
444         {
445                 unsigned int chain = page->offset;
446                 while (chain < pool->allocation) {
447                         if (chain != offset) {
448                                 chain = *(int *)(page->vaddr + chain);
449                                 continue;
450                         }
451                         spin_unlock_irqrestore(&pool->lock, flags);
452                         if (pool->dev)
453                                 dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
454                                         pool->name, (unsigned long long)dma);
455                         else
456                                 pr_err("dma_pool_free %s, dma %Lx already free\n",
457                                        pool->name, (unsigned long long)dma);
458                         return;
459                 }
460         }
461         memset(vaddr, POOL_POISON_FREED, pool->size);
462 #endif
463 
464         page->in_use--;
465         *(int *)vaddr = page->offset;
466         page->offset = offset;
467         /*
468          * Resist a temptation to do
469          *    if (!is_page_busy(page)) pool_free_page(pool, page);
470          * Better have a few empty pages hang around.
471          */
472         spin_unlock_irqrestore(&pool->lock, flags);
473 }
474 EXPORT_SYMBOL(dma_pool_free);
475 
476 /*
477  * Managed DMA pool
478  */
479 static void dmam_pool_release(struct device *dev, void *res)
480 {
481         struct dma_pool *pool = *(struct dma_pool **)res;
482 
483         dma_pool_destroy(pool);
484 }
485 
486 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
487 {
488         return *(struct dma_pool **)res == match_data;
489 }
490 
491 /**
492  * dmam_pool_create - Managed dma_pool_create()
493  * @name: name of pool, for diagnostics
494  * @dev: device that will be doing the DMA
495  * @size: size of the blocks in this pool.
496  * @align: alignment requirement for blocks; must be a power of two
497  * @allocation: returned blocks won't cross this boundary (or zero)
498  *
499  * Managed dma_pool_create().  DMA pool created with this function is
500  * automatically destroyed on driver detach.
501  */
502 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
503                                   size_t size, size_t align, size_t allocation)
504 {
505         struct dma_pool **ptr, *pool;
506 
507         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
508         if (!ptr)
509                 return NULL;
510 
511         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
512         if (pool)
513                 devres_add(dev, ptr);
514         else
515                 devres_free(ptr);
516 
517         return pool;
518 }
519 EXPORT_SYMBOL(dmam_pool_create);
520 
521 /**
522  * dmam_pool_destroy - Managed dma_pool_destroy()
523  * @pool: dma pool that will be destroyed
524  *
525  * Managed dma_pool_destroy().
526  */
527 void dmam_pool_destroy(struct dma_pool *pool)
528 {
529         struct device *dev = pool->dev;
530 
531         WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
532 }
533 EXPORT_SYMBOL(dmam_pool_destroy);
534 

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