Re: [Linaro-mm-sig] [v3 1/4] ARM: dma-mapping: atomic_pool with struct page **pages

On Fri, Aug 24, 2012 at 11:29:02AM +0300, Hiroshi Doyu wrote:

struct page **pages is necessary to align with non atomic path in __iommu_get_pages(). atomic_pool() has the intialized **pages instead of just *page.

Signed-off-by: Hiroshi Doyu hdoyu@nvidia.com

arch/arm/mm/dma-mapping.c | 17 +++++++++++++---- 1 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 601da7a..b14ee64 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -296,7 +296,7 @@ struct dma_pool { unsigned long *bitmap; unsigned long nr_pages; void *vaddr;

• struct page *page;

• struct page **pages;

}; static struct dma_pool atomic_pool = { @@ -335,12 +335,16 @@ static int __init atomic_pool_init(void) unsigned long nr_pages = pool->size >> PAGE_SHIFT; unsigned long *bitmap; struct page *page;

• struct page **pages; void *ptr; int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long);
• size_t size = nr_pages * sizeof(struct page *);

• bitmap = kzalloc(bitmap_size, GFP_KERNEL);

• size += bitmap_size;
• bitmap = kzalloc(size, GFP_KERNEL); if (!bitmap) goto no_bitmap;
• pages = (void *)bitmap + bitmap_size;

So you stuck a bitmap field in front of the array then? Why not just define a structure where this is clearly defined instead of doing the casting.

if (IS_ENABLED(CONFIG_CMA)) ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page); @@ -348,9 +352,14 @@ static int __init atomic_pool_init(void) ptr = __alloc_remap_buffer(NULL, pool->size, GFP_KERNEL, prot, &page, NULL); if (ptr) {

• int i;
  

• for (i = 0; i < nr_pages; i++)
  

• 	pages[i] = page + i;
  

• spin_lock_init(&pool->lock); pool->vaddr = ptr;

• pool->page = page;
  

• pool->pages = pages;
  

  pool->bitmap = bitmap; pool->nr_pages = nr_pages; pr_info("DMA: preallocated %u KiB pool for atomic coherent allocations\n",

@@ -481,7 +490,7 @@ static void *__alloc_from_pool(size_t size, struct page **ret_page) if (pageno < pool->nr_pages) { bitmap_set(pool->bitmap, pageno, count); ptr = pool->vaddr + PAGE_SIZE * pageno;

• *ret_page = pool->page + pageno;
  

• *ret_page = pool->pages[pageno];
  

  } else { pr_err_once("ERROR: %u KiB atomic DMA coherent pool is too small!\n" "Please increase it with coherent_pool= kernel parameter!\n",

-- 1.7.5.4