FreeBSD/Linux Kernel Cross Reference
sys/mm/dmapool.c

     /*
      * DMA Pool allocator
      *
      * Copyright 2001 David Brownell
      * Copyright 2007 Intel Corporation
      *   Author: Matthew Wilcox <willy@linux.intel.com>
      *
      * This software may be redistributed and/or modified under the terms of
      * the GNU General Public License ("GPL") version 2 as published by the
     * Free Software Foundation.
     *
     * This allocator returns small blocks of a given size which are DMA-able by
     * the given device.  It uses the dma_alloc_coherent page allocator to get
     * new pages, then splits them up into blocks of the required size.
     * Many older drivers still have their own code to do this.
     *
     * The current design of this allocator is fairly simple.  The pool is
     * represented by the 'struct dma_pool' which keeps a doubly-linked list of
     * allocated pages.  Each page in the page_list is split into blocks of at
     * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
     * list of free blocks within the page.  Used blocks aren't tracked, but we
     * keep a count of how many are currently allocated from each page.
     */
    
    #include <linux/device.h>
    #include <linux/dma-mapping.h>
    #include <linux/dmapool.h>
    #include <linux/kernel.h>
    #include <linux/list.h>
    #include <linux/export.h>
    #include <linux/mutex.h>
    #include <linux/poison.h>
    #include <linux/sched.h>
    #include <linux/slab.h>
    #include <linux/stat.h>
    #include <linux/spinlock.h>
    #include <linux/string.h>
    #include <linux/types.h>
    #include <linux/wait.h>
    
    #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
    #define DMAPOOL_DEBUG 1
    #endif
    
    struct dma_pool {               /* the pool */
            struct list_head page_list;
            spinlock_t lock;
            size_t size;
            struct device *dev;
            size_t allocation;
            size_t boundary;
            char name[32];
            struct list_head pools;
    };
    
    struct dma_page {               /* cacheable header for 'allocation' bytes */
            struct list_head page_list;
            void *vaddr;
            dma_addr_t dma;
            unsigned int in_use;
            unsigned int offset;
    };
    
    static DEFINE_MUTEX(pools_lock);
    
    static ssize_t
    show_pools(struct device *dev, struct device_attribute *attr, char *buf)
    {
            unsigned temp;
            unsigned size;
            char *next;
            struct dma_page *page;
            struct dma_pool *pool;
    
            next = buf;
            size = PAGE_SIZE;
    
            temp = scnprintf(next, size, "poolinfo - 0.1\n");
            size -= temp;
            next += temp;
    
            mutex_lock(&pools_lock);
            list_for_each_entry(pool, &dev->dma_pools, pools) {
                    unsigned pages = 0;
                    unsigned blocks = 0;
    
                    spin_lock_irq(&pool->lock);
                    list_for_each_entry(page, &pool->page_list, page_list) {
                            pages++;
                            blocks += page->in_use;
                    }
                    spin_unlock_irq(&pool->lock);
    
                    /* per-pool info, no real statistics yet */
                    temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
                                     pool->name, blocks,
                                     pages * (pool->allocation / pool->size),
                                     pool->size, pages);
                    size -= temp;
                   next += temp;
           }
           mutex_unlock(&pools_lock);
   
           return PAGE_SIZE - size;
   }
   
   static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
   
   /**
    * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
    * @name: name of pool, for diagnostics
    * @dev: device that will be doing the DMA
    * @size: size of the blocks in this pool.
    * @align: alignment requirement for blocks; must be a power of two
    * @boundary: returned blocks won't cross this power of two boundary
    * Context: !in_interrupt()
    *
    * Returns a dma allocation pool with the requested characteristics, or
    * null if one can't be created.  Given one of these pools, dma_pool_alloc()
    * may be used to allocate memory.  Such memory will all have "consistent"
    * DMA mappings, accessible by the device and its driver without using
    * cache flushing primitives.  The actual size of blocks allocated may be
    * larger than requested because of alignment.
    *
    * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
    * cross that size boundary.  This is useful for devices which have
    * addressing restrictions on individual DMA transfers, such as not crossing
    * boundaries of 4KBytes.
    */
   struct dma_pool *dma_pool_create(const char *name, struct device *dev,
                                    size_t size, size_t align, size_t boundary)
   {
           struct dma_pool *retval;
           size_t allocation;
   
           if (align == 0) {
                   align = 1;
           } else if (align & (align - 1)) {
                   return NULL;
           }
   
           if (size == 0) {
                   return NULL;
           } else if (size < 4) {
                   size = 4;
           }
   
           if ((size % align) != 0)
                   size = ALIGN(size, align);
   
           allocation = max_t(size_t, size, PAGE_SIZE);
   
           if (!boundary) {
                   boundary = allocation;
           } else if ((boundary < size) || (boundary & (boundary - 1))) {
                   return NULL;
           }
   
           retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
           if (!retval)
                   return retval;
   
           strlcpy(retval->name, name, sizeof(retval->name));
   
           retval->dev = dev;
   
           INIT_LIST_HEAD(&retval->page_list);
           spin_lock_init(&retval->lock);
           retval->size = size;
           retval->boundary = boundary;
           retval->allocation = allocation;
   
           if (dev) {
                   int ret;
   
                   mutex_lock(&pools_lock);
                   if (list_empty(&dev->dma_pools))
                           ret = device_create_file(dev, &dev_attr_pools);
                   else
                           ret = 0;
                   /* note:  not currently insisting "name" be unique */
                   if (!ret)
                           list_add(&retval->pools, &dev->dma_pools);
                   else {
                           kfree(retval);
                           retval = NULL;
                   }
                   mutex_unlock(&pools_lock);
           } else
                   INIT_LIST_HEAD(&retval->pools);
   
           return retval;
   }
   EXPORT_SYMBOL(dma_pool_create);
   
   static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
   {
           unsigned int offset = 0;
           unsigned int next_boundary = pool->boundary;
   
           do {
                   unsigned int next = offset + pool->size;
                   if (unlikely((next + pool->size) >= next_boundary)) {
                           next = next_boundary;
                           next_boundary += pool->boundary;
                   }
                   *(int *)(page->vaddr + offset) = next;
                   offset = next;
           } while (offset < pool->allocation);
   }
   
   static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
   {
           struct dma_page *page;
   
           page = kmalloc(sizeof(*page), mem_flags);
           if (!page)
                   return NULL;
           page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
                                            &page->dma, mem_flags);
           if (page->vaddr) {
   #ifdef  DMAPOOL_DEBUG
                   memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
   #endif
                   pool_initialise_page(pool, page);
                   page->in_use = 0;
                   page->offset = 0;
           } else {
                   kfree(page);
                   page = NULL;
           }
           return page;
   }
   
   static inline int is_page_busy(struct dma_page *page)
   {
           return page->in_use != 0;
   }
   
   static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
   {
           dma_addr_t dma = page->dma;
   
   #ifdef  DMAPOOL_DEBUG
           memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
   #endif
           dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
           list_del(&page->page_list);
           kfree(page);
   }
   
   /**
    * dma_pool_destroy - destroys a pool of dma memory blocks.
    * @pool: dma pool that will be destroyed
    * Context: !in_interrupt()
    *
    * Caller guarantees that no more memory from the pool is in use,
    * and that nothing will try to use the pool after this call.
    */
   void dma_pool_destroy(struct dma_pool *pool)
   {
           mutex_lock(&pools_lock);
           list_del(&pool->pools);
           if (pool->dev && list_empty(&pool->dev->dma_pools))
                   device_remove_file(pool->dev, &dev_attr_pools);
           mutex_unlock(&pools_lock);
   
           while (!list_empty(&pool->page_list)) {
                   struct dma_page *page;
                   page = list_entry(pool->page_list.next,
                                     struct dma_page, page_list);
                   if (is_page_busy(page)) {
                           if (pool->dev)
                                   dev_err(pool->dev,
                                           "dma_pool_destroy %s, %p busy\n",
                                           pool->name, page->vaddr);
                           else
                                   printk(KERN_ERR
                                          "dma_pool_destroy %s, %p busy\n",
                                          pool->name, page->vaddr);
                           /* leak the still-in-use consistent memory */
                           list_del(&page->page_list);
                           kfree(page);
                   } else
                           pool_free_page(pool, page);
           }
   
           kfree(pool);
   }
   EXPORT_SYMBOL(dma_pool_destroy);
   
   /**
    * dma_pool_alloc - get a block of consistent memory
    * @pool: dma pool that will produce the block
    * @mem_flags: GFP_* bitmask
    * @handle: pointer to dma address of block
    *
    * This returns the kernel virtual address of a currently unused block,
    * and reports its dma address through the handle.
    * If such a memory block can't be allocated, %NULL is returned.
    */
   void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
                        dma_addr_t *handle)
   {
           unsigned long flags;
           struct dma_page *page;
           size_t offset;
           void *retval;
   
           might_sleep_if(mem_flags & __GFP_WAIT);
   
           spin_lock_irqsave(&pool->lock, flags);
           list_for_each_entry(page, &pool->page_list, page_list) {
                   if (page->offset < pool->allocation)
                           goto ready;
           }
   
           /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
           spin_unlock_irqrestore(&pool->lock, flags);
   
           page = pool_alloc_page(pool, mem_flags);
           if (!page)
                   return NULL;
   
           spin_lock_irqsave(&pool->lock, flags);
   
           list_add(&page->page_list, &pool->page_list);
    ready:
           page->in_use++;
           offset = page->offset;
           page->offset = *(int *)(page->vaddr + offset);
           retval = offset + page->vaddr;
           *handle = offset + page->dma;
   #ifdef  DMAPOOL_DEBUG
           {
                   int i;
                   u8 *data = retval;
                   /* page->offset is stored in first 4 bytes */
                   for (i = sizeof(page->offset); i < pool->size; i++) {
                           if (data[i] == POOL_POISON_FREED)
                                   continue;
                           if (pool->dev)
                                   dev_err(pool->dev,
                                           "dma_pool_alloc %s, %p (corruped)\n",
                                           pool->name, retval);
                           else
                                   pr_err("dma_pool_alloc %s, %p (corruped)\n",
                                           pool->name, retval);
   
                           /*
                            * Dump the first 4 bytes even if they are not
                            * POOL_POISON_FREED
                            */
                           print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
                                           data, pool->size, 1);
                           break;
                   }
           }
           memset(retval, POOL_POISON_ALLOCATED, pool->size);
   #endif
           spin_unlock_irqrestore(&pool->lock, flags);
           return retval;
   }
   EXPORT_SYMBOL(dma_pool_alloc);
   
   static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
   {
           struct dma_page *page;
   
           list_for_each_entry(page, &pool->page_list, page_list) {
                   if (dma < page->dma)
                           continue;
                   if (dma < (page->dma + pool->allocation))
                           return page;
           }
           return NULL;
   }
   
   /**
    * dma_pool_free - put block back into dma pool
    * @pool: the dma pool holding the block
    * @vaddr: virtual address of block
    * @dma: dma address of block
    *
    * Caller promises neither device nor driver will again touch this block
    * unless it is first re-allocated.
    */
   void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
   {
           struct dma_page *page;
           unsigned long flags;
           unsigned int offset;
   
           spin_lock_irqsave(&pool->lock, flags);
           page = pool_find_page(pool, dma);
           if (!page) {
                   spin_unlock_irqrestore(&pool->lock, flags);
                   if (pool->dev)
                           dev_err(pool->dev,
                                   "dma_pool_free %s, %p/%lx (bad dma)\n",
                                   pool->name, vaddr, (unsigned long)dma);
                   else
                           printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
                                  pool->name, vaddr, (unsigned long)dma);
                   return;
           }
   
           offset = vaddr - page->vaddr;
   #ifdef  DMAPOOL_DEBUG
           if ((dma - page->dma) != offset) {
                   spin_unlock_irqrestore(&pool->lock, flags);
                   if (pool->dev)
                           dev_err(pool->dev,
                                   "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
                                   pool->name, vaddr, (unsigned long long)dma);
                   else
                           printk(KERN_ERR
                                  "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
                                  pool->name, vaddr, (unsigned long long)dma);
                   return;
           }
           {
                   unsigned int chain = page->offset;
                   while (chain < pool->allocation) {
                           if (chain != offset) {
                                   chain = *(int *)(page->vaddr + chain);
                                   continue;
                           }
                           spin_unlock_irqrestore(&pool->lock, flags);
                           if (pool->dev)
                                   dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
                                           "already free\n", pool->name,
                                           (unsigned long long)dma);
                           else
                                   printk(KERN_ERR "dma_pool_free %s, dma %Lx "
                                           "already free\n", pool->name,
                                           (unsigned long long)dma);
                           return;
                   }
           }
           memset(vaddr, POOL_POISON_FREED, pool->size);
   #endif
   
           page->in_use--;
           *(int *)vaddr = page->offset;
           page->offset = offset;
           /*
            * Resist a temptation to do
            *    if (!is_page_busy(page)) pool_free_page(pool, page);
            * Better have a few empty pages hang around.
            */
           spin_unlock_irqrestore(&pool->lock, flags);
   }
   EXPORT_SYMBOL(dma_pool_free);
   
   /*
    * Managed DMA pool
    */
   static void dmam_pool_release(struct device *dev, void *res)
   {
           struct dma_pool *pool = *(struct dma_pool **)res;
   
           dma_pool_destroy(pool);
   }
   
   static int dmam_pool_match(struct device *dev, void *res, void *match_data)
   {
           return *(struct dma_pool **)res == match_data;
   }
   
   /**
    * dmam_pool_create - Managed dma_pool_create()
    * @name: name of pool, for diagnostics
    * @dev: device that will be doing the DMA
    * @size: size of the blocks in this pool.
    * @align: alignment requirement for blocks; must be a power of two
    * @allocation: returned blocks won't cross this boundary (or zero)
    *
    * Managed dma_pool_create().  DMA pool created with this function is
    * automatically destroyed on driver detach.
    */
   struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
                                     size_t size, size_t align, size_t allocation)
   {
           struct dma_pool **ptr, *pool;
   
           ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
           if (!ptr)
                   return NULL;
   
           pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
           if (pool)
                   devres_add(dev, ptr);
           else
                   devres_free(ptr);
   
           return pool;
   }
   EXPORT_SYMBOL(dmam_pool_create);
   
   /**
    * dmam_pool_destroy - Managed dma_pool_destroy()
    * @pool: dma pool that will be destroyed
    *
    * Managed dma_pool_destroy().
    */
   void dmam_pool_destroy(struct dma_pool *pool)
   {
           struct device *dev = pool->dev;
   
           WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
           dma_pool_destroy(pool);
   }
   EXPORT_SYMBOL(dmam_pool_destroy);

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