root/mm/dmapool.c

DEFINITIONS

1. show_pools
2. dma_pool_create
3. pool_initialise_page
4. pool_alloc_page
5. is_page_busy
6. pool_free_page
7. dma_pool_destroy
8. dma_pool_alloc
9. pool_find_page
10. dma_pool_free
11. dmam_pool_release
12. dmam_pool_match
13. dmam_pool_create
14. dmam_pool_destroy

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * DMA Pool allocator
   4  *
   5  * Copyright 2001 David Brownell
   6  * Copyright 2007 Intel Corporation
   7  *   Author: Matthew Wilcox <willy@linux.intel.com>
   8  *
   9  * This allocator returns small blocks of a given size which are DMA-able by
  10  * the given device.  It uses the dma_alloc_coherent page allocator to get
  11  * new pages, then splits them up into blocks of the required size.
  12  * Many older drivers still have their own code to do this.
  13  *
  14  * The current design of this allocator is fairly simple.  The pool is
  15  * represented by the 'struct dma_pool' which keeps a doubly-linked list of
  16  * allocated pages.  Each page in the page_list is split into blocks of at
  17  * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
  18  * list of free blocks within the page.  Used blocks aren't tracked, but we
  19  * keep a count of how many are currently allocated from each page.
  20  */
  21 
  22 #include <linux/device.h>
  23 #include <linux/dma-mapping.h>
  24 #include <linux/dmapool.h>
  25 #include <linux/kernel.h>
  26 #include <linux/list.h>
  27 #include <linux/export.h>
  28 #include <linux/mutex.h>
  29 #include <linux/poison.h>
  30 #include <linux/sched.h>
  31 #include <linux/slab.h>
  32 #include <linux/stat.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/string.h>
  35 #include <linux/types.h>
  36 #include <linux/wait.h>
  37 
  38 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
  39 #define DMAPOOL_DEBUG 1
  40 #endif
  41 
  42 struct dma_pool {               /* the pool */
  43         struct list_head page_list;
  44         spinlock_t lock;
  45         size_t size;
  46         struct device *dev;
  47         size_t allocation;
  48         size_t boundary;
  49         char name[32];
  50         struct list_head pools;
  51 };
  52 
  53 struct dma_page {               /* cacheable header for 'allocation' bytes */
  54         struct list_head page_list;
  55         void *vaddr;
  56         dma_addr_t dma;
  57         unsigned int in_use;
  58         unsigned int offset;
  59 };
  60 
  61 static DEFINE_MUTEX(pools_lock);
  62 static DEFINE_MUTEX(pools_reg_lock);
  63 
  64 static ssize_t
  65 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  66 {
  67         unsigned temp;
  68         unsigned size;
  69         char *next;
  70         struct dma_page *page;
  71         struct dma_pool *pool;
  72 
  73         next = buf;
  74         size = PAGE_SIZE;
  75 
  76         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  77         size -= temp;
  78         next += temp;
  79 
  80         mutex_lock(&pools_lock);
  81         list_for_each_entry(pool, &dev->dma_pools, pools) {
  82                 unsigned pages = 0;
  83                 unsigned blocks = 0;
  84 
  85                 spin_lock_irq(&pool->lock);
  86                 list_for_each_entry(page, &pool->page_list, page_list) {
  87                         pages++;
  88                         blocks += page->in_use;
  89                 }
  90                 spin_unlock_irq(&pool->lock);
  91 
  92                 /* per-pool info, no real statistics yet */
  93                 temp = scnprintf(next, size, "%-16s %4u %4zu %4zu %2u\n",
  94                                  pool->name, blocks,
  95                                  pages * (pool->allocation / pool->size),
  96                                  pool->size, pages);
  97                 size -= temp;
  98                 next += temp;
  99         }
 100         mutex_unlock(&pools_lock);
 101 
 102         return PAGE_SIZE - size;
 103 }
 104 
 105 static DEVICE_ATTR(pools, 0444, show_pools, NULL);
 106 
 107 /**
 108  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 109  * @name: name of pool, for diagnostics
 110  * @dev: device that will be doing the DMA
 111  * @size: size of the blocks in this pool.
 112  * @align: alignment requirement for blocks; must be a power of two
 113  * @boundary: returned blocks won't cross this power of two boundary
 114  * Context: not in_interrupt()
 115  *
 116  * Given one of these pools, dma_pool_alloc()
 117  * may be used to allocate memory.  Such memory will all have "consistent"
 118  * DMA mappings, accessible by the device and its driver without using
 119  * cache flushing primitives.  The actual size of blocks allocated may be
 120  * larger than requested because of alignment.
 121  *
 122  * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 123  * cross that size boundary.  This is useful for devices which have
 124  * addressing restrictions on individual DMA transfers, such as not crossing
 125  * boundaries of 4KBytes.
 126  *
 127  * Return: a dma allocation pool with the requested characteristics, or
 128  * %NULL if one can't be created.
 129  */
 130 struct 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         bool empty = false;
 136 
 137         if (align == 0)
 138                 align = 1;
 139         else if (align & (align - 1))
 140                 return NULL;
 141 
 142         if (size == 0)
 143                 return NULL;
 144         else if (size < 4)
 145                 size = 4;
 146 
 147         if ((size % align) != 0)
 148                 size = ALIGN(size, align);
 149 
 150         allocation = max_t(size_t, size, PAGE_SIZE);
 151 
 152         if (!boundary)
 153                 boundary = allocation;
 154         else if ((boundary < size) || (boundary & (boundary - 1)))
 155                 return NULL;
 156 
 157         retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
 158         if (!retval)
 159                 return retval;
 160 
 161         strlcpy(retval->name, name, sizeof(retval->name));
 162 
 163         retval->dev = dev;
 164 
 165         INIT_LIST_HEAD(&retval->page_list);
 166         spin_lock_init(&retval->lock);
 167         retval->size = size;
 168         retval->boundary = boundary;
 169         retval->allocation = allocation;
 170 
 171         INIT_LIST_HEAD(&retval->pools);
 172 
 173         /*
 174          * pools_lock ensures that the ->dma_pools list does not get corrupted.
 175          * pools_reg_lock ensures that there is not a race between
 176          * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
 177          * when the first invocation of dma_pool_create() failed on
 178          * device_create_file() and the second assumes that it has been done (I
 179          * know it is a short window).
 180          */
 181         mutex_lock(&pools_reg_lock);
 182         mutex_lock(&pools_lock);
 183         if (list_empty(&dev->dma_pools))
 184                 empty = true;
 185         list_add(&retval->pools, &dev->dma_pools);
 186         mutex_unlock(&pools_lock);
 187         if (empty) {
 188                 int err;
 189 
 190                 err = device_create_file(dev, &dev_attr_pools);
 191                 if (err) {
 192                         mutex_lock(&pools_lock);
 193                         list_del(&retval->pools);
 194                         mutex_unlock(&pools_lock);
 195                         mutex_unlock(&pools_reg_lock);
 196                         kfree(retval);
 197                         return NULL;
 198                 }
 199         }
 200         mutex_unlock(&pools_reg_lock);
 201         return retval;
 202 }
 203 EXPORT_SYMBOL(dma_pool_create);
 204 
 205 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 206 {
 207         unsigned int offset = 0;
 208         unsigned int next_boundary = pool->boundary;
 209 
 210         do {
 211                 unsigned int next = offset + pool->size;
 212                 if (unlikely((next + pool->size) >= next_boundary)) {
 213                         next = next_boundary;
 214                         next_boundary += pool->boundary;
 215                 }
 216                 *(int *)(page->vaddr + offset) = next;
 217                 offset = next;
 218         } while (offset < pool->allocation);
 219 }
 220 
 221 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 222 {
 223         struct dma_page *page;
 224 
 225         page = kmalloc(sizeof(*page), mem_flags);
 226         if (!page)
 227                 return NULL;
 228         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 229                                          &page->dma, mem_flags);
 230         if (page->vaddr) {
 231 #ifdef  DMAPOOL_DEBUG
 232                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 233 #endif
 234                 pool_initialise_page(pool, page);
 235                 page->in_use = 0;
 236                 page->offset = 0;
 237         } else {
 238                 kfree(page);
 239                 page = NULL;
 240         }
 241         return page;
 242 }
 243 
 244 static inline bool is_page_busy(struct dma_page *page)
 245 {
 246         return page->in_use != 0;
 247 }
 248 
 249 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 250 {
 251         dma_addr_t dma = page->dma;
 252 
 253 #ifdef  DMAPOOL_DEBUG
 254         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 255 #endif
 256         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 257         list_del(&page->page_list);
 258         kfree(page);
 259 }
 260 
 261 /**
 262  * dma_pool_destroy - destroys a pool of dma memory blocks.
 263  * @pool: dma pool that will be destroyed
 264  * Context: !in_interrupt()
 265  *
 266  * Caller guarantees that no more memory from the pool is in use,
 267  * and that nothing will try to use the pool after this call.
 268  */
 269 void dma_pool_destroy(struct dma_pool *pool)
 270 {
 271         bool empty = false;
 272 
 273         if (unlikely(!pool))
 274                 return;
 275 
 276         mutex_lock(&pools_reg_lock);
 277         mutex_lock(&pools_lock);
 278         list_del(&pool->pools);
 279         if (pool->dev && list_empty(&pool->dev->dma_pools))
 280                 empty = true;
 281         mutex_unlock(&pools_lock);
 282         if (empty)
 283                 device_remove_file(pool->dev, &dev_attr_pools);
 284         mutex_unlock(&pools_reg_lock);
 285 
 286         while (!list_empty(&pool->page_list)) {
 287                 struct dma_page *page;
 288                 page = list_entry(pool->page_list.next,
 289                                   struct dma_page, page_list);
 290                 if (is_page_busy(page)) {
 291                         if (pool->dev)
 292                                 dev_err(pool->dev,
 293                                         "dma_pool_destroy %s, %p busy\n",
 294                                         pool->name, page->vaddr);
 295                         else
 296                                 pr_err("dma_pool_destroy %s, %p busy\n",
 297                                        pool->name, page->vaddr);
 298                         /* leak the still-in-use consistent memory */
 299                         list_del(&page->page_list);
 300                         kfree(page);
 301                 } else
 302                         pool_free_page(pool, page);
 303         }
 304 
 305         kfree(pool);
 306 }
 307 EXPORT_SYMBOL(dma_pool_destroy);
 308 
 309 /**
 310  * dma_pool_alloc - get a block of consistent memory
 311  * @pool: dma pool that will produce the block
 312  * @mem_flags: GFP_* bitmask
 313  * @handle: pointer to dma address of block
 314  *
 315  * Return: the kernel virtual address of a currently unused block,
 316  * and reports its dma address through the handle.
 317  * If such a memory block can't be allocated, %NULL is returned.
 318  */
 319 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 320                      dma_addr_t *handle)
 321 {
 322         unsigned long flags;
 323         struct dma_page *page;
 324         size_t offset;
 325         void *retval;
 326 
 327         might_sleep_if(gfpflags_allow_blocking(mem_flags));
 328 
 329         spin_lock_irqsave(&pool->lock, flags);
 330         list_for_each_entry(page, &pool->page_list, page_list) {
 331                 if (page->offset < pool->allocation)
 332                         goto ready;
 333         }
 334 
 335         /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
 336         spin_unlock_irqrestore(&pool->lock, flags);
 337 
 338         page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
 339         if (!page)
 340                 return NULL;
 341 
 342         spin_lock_irqsave(&pool->lock, flags);
 343 
 344         list_add(&page->page_list, &pool->page_list);
 345  ready:
 346         page->in_use++;
 347         offset = page->offset;
 348         page->offset = *(int *)(page->vaddr + offset);
 349         retval = offset + page->vaddr;
 350         *handle = offset + page->dma;
 351 #ifdef  DMAPOOL_DEBUG
 352         {
 353                 int i;
 354                 u8 *data = retval;
 355                 /* page->offset is stored in first 4 bytes */
 356                 for (i = sizeof(page->offset); i < pool->size; i++) {
 357                         if (data[i] == POOL_POISON_FREED)
 358                                 continue;
 359                         if (pool->dev)
 360                                 dev_err(pool->dev,
 361                                         "dma_pool_alloc %s, %p (corrupted)\n",
 362                                         pool->name, retval);
 363                         else
 364                                 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
 365                                         pool->name, retval);
 366 
 367                         /*
 368                          * Dump the first 4 bytes even if they are not
 369                          * POOL_POISON_FREED
 370                          */
 371                         print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
 372                                         data, pool->size, 1);
 373                         break;
 374                 }
 375         }
 376         if (!(mem_flags & __GFP_ZERO))
 377                 memset(retval, POOL_POISON_ALLOCATED, pool->size);
 378 #endif
 379         spin_unlock_irqrestore(&pool->lock, flags);
 380 
 381         if (want_init_on_alloc(mem_flags))
 382                 memset(retval, 0, pool->size);
 383 
 384         return retval;
 385 }
 386 EXPORT_SYMBOL(dma_pool_alloc);
 387 
 388 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 389 {
 390         struct dma_page *page;
 391 
 392         list_for_each_entry(page, &pool->page_list, page_list) {
 393                 if (dma < page->dma)
 394                         continue;
 395                 if ((dma - page->dma) < pool->allocation)
 396                         return page;
 397         }
 398         return NULL;
 399 }
 400 
 401 /**
 402  * dma_pool_free - put block back into dma pool
 403  * @pool: the dma pool holding the block
 404  * @vaddr: virtual address of block
 405  * @dma: dma address of block
 406  *
 407  * Caller promises neither device nor driver will again touch this block
 408  * unless it is first re-allocated.
 409  */
 410 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 411 {
 412         struct dma_page *page;
 413         unsigned long flags;
 414         unsigned int offset;
 415 
 416         spin_lock_irqsave(&pool->lock, flags);
 417         page = pool_find_page(pool, dma);
 418         if (!page) {
 419                 spin_unlock_irqrestore(&pool->lock, flags);
 420                 if (pool->dev)
 421                         dev_err(pool->dev,
 422                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
 423                                 pool->name, vaddr, (unsigned long)dma);
 424                 else
 425                         pr_err("dma_pool_free %s, %p/%lx (bad dma)\n",
 426                                pool->name, vaddr, (unsigned long)dma);
 427                 return;
 428         }
 429 
 430         offset = vaddr - page->vaddr;
 431         if (want_init_on_free())
 432                 memset(vaddr, 0, pool->size);
 433 #ifdef  DMAPOOL_DEBUG
 434         if ((dma - page->dma) != offset) {
 435                 spin_unlock_irqrestore(&pool->lock, flags);
 436                 if (pool->dev)
 437                         dev_err(pool->dev,
 438                                 "dma_pool_free %s, %p (bad vaddr)/%pad\n",
 439                                 pool->name, vaddr, &dma);
 440                 else
 441                         pr_err("dma_pool_free %s, %p (bad vaddr)/%pad\n",
 442                                pool->name, vaddr, &dma);
 443                 return;
 444         }
 445         {
 446                 unsigned int chain = page->offset;
 447                 while (chain < pool->allocation) {
 448                         if (chain != offset) {
 449                                 chain = *(int *)(page->vaddr + chain);
 450                                 continue;
 451                         }
 452                         spin_unlock_irqrestore(&pool->lock, flags);
 453                         if (pool->dev)
 454                                 dev_err(pool->dev, "dma_pool_free %s, dma %pad already free\n",
 455                                         pool->name, &dma);
 456                         else
 457                                 pr_err("dma_pool_free %s, dma %pad already free\n",
 458                                        pool->name, &dma);
 459                         return;
 460                 }
 461         }
 462         memset(vaddr, POOL_POISON_FREED, pool->size);
 463 #endif
 464 
 465         page->in_use--;
 466         *(int *)vaddr = page->offset;
 467         page->offset = offset;
 468         /*
 469          * Resist a temptation to do
 470          *    if (!is_page_busy(page)) pool_free_page(pool, page);
 471          * Better have a few empty pages hang around.
 472          */
 473         spin_unlock_irqrestore(&pool->lock, flags);
 474 }
 475 EXPORT_SYMBOL(dma_pool_free);
 476 
 477 /*
 478  * Managed DMA pool
 479  */
 480 static void dmam_pool_release(struct device *dev, void *res)
 481 {
 482         struct dma_pool *pool = *(struct dma_pool **)res;
 483 
 484         dma_pool_destroy(pool);
 485 }
 486 
 487 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 488 {
 489         return *(struct dma_pool **)res == match_data;
 490 }
 491 
 492 /**
 493  * dmam_pool_create - Managed dma_pool_create()
 494  * @name: name of pool, for diagnostics
 495  * @dev: device that will be doing the DMA
 496  * @size: size of the blocks in this pool.
 497  * @align: alignment requirement for blocks; must be a power of two
 498  * @allocation: returned blocks won't cross this boundary (or zero)
 499  *
 500  * Managed dma_pool_create().  DMA pool created with this function is
 501  * automatically destroyed on driver detach.
 502  *
 503  * Return: a managed dma allocation pool with the requested
 504  * characteristics, or %NULL if one can't be created.
 505  */
 506 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 507                                   size_t size, size_t align, size_t allocation)
 508 {
 509         struct dma_pool **ptr, *pool;
 510 
 511         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 512         if (!ptr)
 513                 return NULL;
 514 
 515         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 516         if (pool)
 517                 devres_add(dev, ptr);
 518         else
 519                 devres_free(ptr);
 520 
 521         return pool;
 522 }
 523 EXPORT_SYMBOL(dmam_pool_create);
 524 
 525 /**
 526  * dmam_pool_destroy - Managed dma_pool_destroy()
 527  * @pool: dma pool that will be destroyed
 528  *
 529  * Managed dma_pool_destroy().
 530  */
 531 void dmam_pool_destroy(struct dma_pool *pool)
 532 {
 533         struct device *dev = pool->dev;
 534 
 535         WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
 536 }
 537 EXPORT_SYMBOL(dmam_pool_destroy);