diff options
| -rw-r--r-- | mm/dmapool.c | 119 |
1 files changed, 58 insertions, 61 deletions
diff --git a/mm/dmapool.c b/mm/dmapool.c index e2ea454..72e7ece 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -17,7 +17,9 @@ * 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. + * 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> @@ -38,7 +40,6 @@ struct dma_pool { /* the pool */ struct list_head page_list; spinlock_t lock; - size_t blocks_per_page; size_t size; struct device *dev; size_t allocation; @@ -51,8 +52,8 @@ struct dma_page { /* cacheable header for 'allocation' bytes */ struct list_head page_list; void *vaddr; dma_addr_t dma; - unsigned in_use; - unsigned long bitmap[0]; + unsigned int in_use; + unsigned int offset; }; #define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000) @@ -87,8 +88,8 @@ show_pools(struct device *dev, struct device_attribute *attr, char *buf) /* per-pool info, no real statistics yet */ temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n", - pool->name, - blocks, pages * pool->blocks_per_page, + pool->name, blocks, + pages * (pool->allocation / pool->size), pool->size, pages); size -= temp; next += temp; @@ -132,8 +133,11 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, return NULL; } - if (size == 0) + if (size == 0) { return NULL; + } else if (size < 4) { + size = 4; + } if ((size % align) != 0) size = ALIGN(size, align); @@ -160,7 +164,6 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, spin_lock_init(&retval->lock); retval->size = size; retval->allocation = allocation; - retval->blocks_per_page = allocation / size; init_waitqueue_head(&retval->waitq); if (dev) { @@ -186,28 +189,36 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, } EXPORT_SYMBOL(dma_pool_create); +static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) +{ + unsigned int offset = 0; + + do { + unsigned int next = offset + pool->size; + if (unlikely((next + pool->size) >= pool->allocation)) + next = pool->allocation; + *(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; - int mapsize; - - mapsize = pool->blocks_per_page; - mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG; - mapsize *= sizeof(long); - page = kmalloc(mapsize + sizeof *page, mem_flags); + page = kmalloc(sizeof(*page), mem_flags); if (!page) return NULL; - page->vaddr = dma_alloc_coherent(pool->dev, - pool->allocation, + page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation, &page->dma, mem_flags); if (page->vaddr) { - memset(page->bitmap, 0xff, mapsize); /* bit set == free */ #ifdef CONFIG_DEBUG_SLAB memset(page->vaddr, POOL_POISON_FREED, pool->allocation); #endif + pool_initialise_page(pool, page); list_add(&page->page_list, &pool->page_list); page->in_use = 0; + page->offset = 0; } else { kfree(page); page = NULL; @@ -215,14 +226,9 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) return page; } -static inline int is_page_busy(int blocks, unsigned long *bitmap) +static inline int is_page_busy(struct dma_page *page) { - while (blocks > 0) { - if (*bitmap++ != ~0UL) - return 1; - blocks -= BITS_PER_LONG; - } - return 0; + return page->in_use != 0; } static void pool_free_page(struct dma_pool *pool, struct dma_page *page) @@ -257,7 +263,7 @@ void dma_pool_destroy(struct dma_pool *pool) struct dma_page *page; page = list_entry(pool->page_list.next, struct dma_page, page_list); - if (is_page_busy(pool->blocks_per_page, page->bitmap)) { + if (is_page_busy(page)) { if (pool->dev) dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n", @@ -292,27 +298,14 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, { unsigned long flags; struct dma_page *page; - int map, block; size_t offset; void *retval; spin_lock_irqsave(&pool->lock, flags); restart: list_for_each_entry(page, &pool->page_list, page_list) { - int i; - /* only cachable accesses here ... */ - for (map = 0, i = 0; - i < pool->blocks_per_page; i += BITS_PER_LONG, map++) { - if (page->bitmap[map] == 0) - continue; - block = ffz(~page->bitmap[map]); - if ((i + block) < pool->blocks_per_page) { - clear_bit(block, &page->bitmap[map]); - offset = (BITS_PER_LONG * map) + block; - offset *= pool->size; - goto ready; - } - } + if (page->offset < pool->allocation) + goto ready; } page = pool_alloc_page(pool, GFP_ATOMIC); if (!page) { @@ -333,10 +326,10 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, goto done; } - clear_bit(0, &page->bitmap[0]); - offset = 0; ready: page->in_use++; + offset = page->offset; + page->offset = *(int *)(page->vaddr + offset); retval = offset + page->vaddr; *handle = offset + page->dma; #ifdef CONFIG_DEBUG_SLAB @@ -379,7 +372,7 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { struct dma_page *page; unsigned long flags; - int map, block; + unsigned int offset; page = pool_find_page(pool, dma); if (!page) { @@ -393,13 +386,9 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) return; } - block = dma - page->dma; - block /= pool->size; - map = block / BITS_PER_LONG; - block %= BITS_PER_LONG; - + offset = vaddr - page->vaddr; #ifdef CONFIG_DEBUG_SLAB - if (((dma - page->dma) + (void *)page->vaddr) != vaddr) { + if ((dma - page->dma) != offset) { if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n", @@ -410,28 +399,36 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) pool->name, vaddr, (unsigned long long)dma); return; } - if (page->bitmap[map] & (1UL << block)) { - 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; + { + unsigned int chain = page->offset; + while (chain < pool->allocation) { + if (chain != offset) { + chain = *(int *)(page->vaddr + chain); + continue; + } + 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 spin_lock_irqsave(&pool->lock, flags); page->in_use--; - set_bit(block, &page->bitmap[map]); + *(int *)vaddr = page->offset; + page->offset = offset; if (waitqueue_active(&pool->waitq)) wake_up_locked(&pool->waitq); /* * Resist a temptation to do - * if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page); + * if (!is_page_busy(page)) pool_free_page(pool, page); * Better have a few empty pages hang around. */ spin_unlock_irqrestore(&pool->lock, flags); |
