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mm/dmapool.c
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/* * 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 |
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* 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. |
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*/ |
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#include <linux/device.h> |
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#include <linux/dma-mapping.h> #include <linux/dmapool.h> |
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#include <linux/kernel.h> #include <linux/list.h> |
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#include <linux/export.h> |
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#include <linux/mutex.h> |
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#include <linux/poison.h> |
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#include <linux/sched.h> |
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#include <linux/slab.h> |
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#include <linux/stat.h> |
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#include <linux/spinlock.h> #include <linux/string.h> #include <linux/types.h> #include <linux/wait.h> |
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#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON) #define DMAPOOL_DEBUG 1 #endif |
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struct dma_pool { /* the pool */ struct list_head page_list; spinlock_t lock; |
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size_t size; struct device *dev; size_t allocation; |
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size_t boundary; |
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char name[32]; |
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struct list_head pools; |
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}; |
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struct dma_page { /* cacheable header for 'allocation' bytes */ struct list_head page_list; void *vaddr; dma_addr_t dma; |
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unsigned int in_use; unsigned int offset; |
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}; |
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static DEFINE_MUTEX(pools_lock); |
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static DEFINE_MUTEX(pools_reg_lock); |
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static ssize_t |
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show_pools(struct device *dev, struct device_attribute *attr, char *buf) |
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{ 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 "); size -= temp; next += temp; |
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mutex_lock(&pools_lock); |
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list_for_each_entry(pool, &dev->dma_pools, pools) { unsigned pages = 0; unsigned blocks = 0; |
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spin_lock_irq(&pool->lock); |
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list_for_each_entry(page, &pool->page_list, page_list) { pages++; blocks += page->in_use; } |
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spin_unlock_irq(&pool->lock); |
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/* per-pool info, no real statistics yet */ temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u ", |
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pool->name, blocks, pages * (pool->allocation / pool->size), |
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pool->size, pages); |
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size -= temp; next += temp; } |
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mutex_unlock(&pools_lock); |
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return PAGE_SIZE - size; } |
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static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL); |
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/** * 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 |
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* @boundary: returned blocks won't cross this power of two boundary |
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* 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. * |
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* If @boundary is nonzero, objects returned from dma_pool_alloc() won't |
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* cross that size boundary. This is useful for devices which have * addressing restrictions on individual DMA transfers, such as not crossing * boundaries of 4KBytes. */ |
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struct dma_pool *dma_pool_create(const char *name, struct device *dev, |
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size_t size, size_t align, size_t boundary) |
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{ |
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struct dma_pool *retval; |
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size_t allocation; |
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bool empty = false; |
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|
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if (align == 0) |
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align = 1; |
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else if (align & (align - 1)) |
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return NULL; |
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|
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if (size == 0) |
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return NULL; |
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else if (size < 4) |
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size = 4; |
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if ((size % align) != 0) size = ALIGN(size, align); |
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allocation = max_t(size_t, size, PAGE_SIZE); |
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if (!boundary) |
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boundary = allocation; |
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else if ((boundary < size) || (boundary & (boundary - 1))) |
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return NULL; |
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retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev)); if (!retval) |
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return retval; |
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strlcpy(retval->name, name, sizeof(retval->name)); |
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retval->dev = dev; |
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INIT_LIST_HEAD(&retval->page_list); spin_lock_init(&retval->lock); |
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retval->size = size; |
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retval->boundary = boundary; |
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retval->allocation = allocation; |
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|
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INIT_LIST_HEAD(&retval->pools); |
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/* * pools_lock ensures that the ->dma_pools list does not get corrupted. * pools_reg_lock ensures that there is not a race between * dma_pool_create() and dma_pool_destroy() or within dma_pool_create() * when the first invocation of dma_pool_create() failed on * device_create_file() and the second assumes that it has been done (I * know it is a short window). */ mutex_lock(&pools_reg_lock); |
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mutex_lock(&pools_lock); |
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if (list_empty(&dev->dma_pools)) empty = true; list_add(&retval->pools, &dev->dma_pools); |
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mutex_unlock(&pools_lock); |
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if (empty) { int err; err = device_create_file(dev, &dev_attr_pools); if (err) { mutex_lock(&pools_lock); list_del(&retval->pools); mutex_unlock(&pools_lock); mutex_unlock(&pools_reg_lock); kfree(retval); return NULL; } } mutex_unlock(&pools_reg_lock); |
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return retval; } |
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EXPORT_SYMBOL(dma_pool_create); |
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static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) { unsigned int offset = 0; |
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unsigned int next_boundary = pool->boundary; |
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do { unsigned int next = offset + pool->size; |
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if (unlikely((next + pool->size) >= next_boundary)) { next = next_boundary; next_boundary += pool->boundary; } |
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*(int *)(page->vaddr + offset) = next; offset = next; } while (offset < pool->allocation); } |
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static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) |
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{ |
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struct dma_page *page; |
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page = kmalloc(sizeof(*page), mem_flags); |
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if (!page) return NULL; |
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page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation, |
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&page->dma, mem_flags); |
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if (page->vaddr) { |
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#ifdef DMAPOOL_DEBUG |
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memset(page->vaddr, POOL_POISON_FREED, pool->allocation); |
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#endif |
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pool_initialise_page(pool, page); |
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page->in_use = 0; |
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page->offset = 0; |
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} else { |
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kfree(page); |
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page = NULL; } return page; } |
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static inline int is_page_busy(struct dma_page *page) |
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{ |
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return page->in_use != 0; |
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} |
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static void pool_free_page(struct dma_pool *pool, struct dma_page *page) |
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{ |
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dma_addr_t dma = page->dma; |
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|
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#ifdef DMAPOOL_DEBUG |
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memset(page->vaddr, POOL_POISON_FREED, pool->allocation); |
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#endif |
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dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma); list_del(&page->page_list); kfree(page); |
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} |
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/** * 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. */ |
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void dma_pool_destroy(struct dma_pool *pool) |
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{ |
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bool empty = false; mutex_lock(&pools_reg_lock); |
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mutex_lock(&pools_lock); |
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list_del(&pool->pools); if (pool->dev && list_empty(&pool->dev->dma_pools)) |
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empty = true; |
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mutex_unlock(&pools_lock); |
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if (empty) device_remove_file(pool->dev, &dev_attr_pools); mutex_unlock(&pools_reg_lock); |
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while (!list_empty(&pool->page_list)) { struct dma_page *page; page = list_entry(pool->page_list.next, struct dma_page, page_list); |
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if (is_page_busy(page)) { |
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if (pool->dev) |
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dev_err(pool->dev, "dma_pool_destroy %s, %p busy ", |
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pool->name, page->vaddr); else |
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printk(KERN_ERR "dma_pool_destroy %s, %p busy ", pool->name, page->vaddr); |
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/* leak the still-in-use consistent memory */ |
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list_del(&page->page_list); kfree(page); |
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} else |
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pool_free_page(pool, page); |
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} |
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kfree(pool); |
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} |
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EXPORT_SYMBOL(dma_pool_destroy); |
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/** * 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. |
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* If such a memory block can't be allocated, %NULL is returned. |
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*/ |
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void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle) |
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{ |
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unsigned long flags; struct dma_page *page; |
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size_t offset; void *retval; |
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might_sleep_if(mem_flags & __GFP_WAIT); |
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spin_lock_irqsave(&pool->lock, flags); |
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list_for_each_entry(page, &pool->page_list, page_list) { |
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if (page->offset < pool->allocation) goto ready; |
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} |
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/* pool_alloc_page() might sleep, so temporarily drop &pool->lock */ spin_unlock_irqrestore(&pool->lock, flags); |
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page = pool_alloc_page(pool, mem_flags); if (!page) return NULL; |
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spin_lock_irqsave(&pool->lock, flags); |
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list_add(&page->page_list, &pool->page_list); |
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ready: |
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page->in_use++; |
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offset = page->offset; page->offset = *(int *)(page->vaddr + offset); |
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retval = offset + page->vaddr; *handle = offset + page->dma; |
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#ifdef DMAPOOL_DEBUG |
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{ 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, |
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"dma_pool_alloc %s, %p (corrupted) ", |
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pool->name, retval); else |
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pr_err("dma_pool_alloc %s, %p (corrupted) ", |
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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; } } |
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memset(retval, POOL_POISON_ALLOCATED, pool->size); |
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#endif |
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spin_unlock_irqrestore(&pool->lock, flags); |
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return retval; } |
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EXPORT_SYMBOL(dma_pool_alloc); |
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|
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static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) |
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{ |
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struct dma_page *page; |
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|
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list_for_each_entry(page, &pool->page_list, page_list) { if (dma < page->dma) continue; if (dma < (page->dma + pool->allocation)) |
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return page; |
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} |
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return NULL; |
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} |
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/** * 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. */ |
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void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) |
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{ |
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struct dma_page *page; unsigned long flags; |
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unsigned int offset; |
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|
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spin_lock_irqsave(&pool->lock, flags); |
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page = pool_find_page(pool, dma); if (!page) { |
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spin_unlock_irqrestore(&pool->lock, flags); |
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if (pool->dev) |
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dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma) ", pool->name, vaddr, (unsigned long)dma); |
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else |
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printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma) ", pool->name, vaddr, (unsigned long)dma); |
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return; } |
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offset = vaddr - page->vaddr; |
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#ifdef DMAPOOL_DEBUG |
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if ((dma - page->dma) != offset) { |
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spin_unlock_irqrestore(&pool->lock, flags); |
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if (pool->dev) |
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dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx ", pool->name, vaddr, (unsigned long long)dma); |
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else |
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printk(KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx ", pool->name, vaddr, (unsigned long long)dma); |
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return; } |
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{ unsigned int chain = page->offset; while (chain < pool->allocation) { if (chain != offset) { chain = *(int *)(page->vaddr + chain); continue; } |
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spin_unlock_irqrestore(&pool->lock, flags); |
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if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, dma %Lx " "already free ", pool->name, (unsigned long long)dma); else printk(KERN_ERR "dma_pool_free %s, dma %Lx " "already free ", pool->name, (unsigned long long)dma); return; } |
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} |
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memset(vaddr, POOL_POISON_FREED, pool->size); |
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#endif |
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page->in_use--; |
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*(int *)vaddr = page->offset; page->offset = offset; |
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/* * Resist a temptation to do |
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* if (!is_page_busy(page)) pool_free_page(pool, page); |
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* Better have a few empty pages hang around. */ |
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spin_unlock_irqrestore(&pool->lock, flags); |
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} |
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EXPORT_SYMBOL(dma_pool_free); |
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|
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/* * 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; } |
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EXPORT_SYMBOL(dmam_pool_create); |
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/** * 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; |
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WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool)); |
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} |
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EXPORT_SYMBOL(dmam_pool_destroy); |