Hello,
On Friday, August 24, 2012 1:52 PM Hiroshi Doyu wrote:
Konrad Rzeszutek Wilk konrad.wilk@oracle.com wrote @ Fri, 24 Aug 2012 13:13:23 +0200:
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.
I just wanted to allocate only once for the members "pool->bitmap" and "pool->pages" at once. Since the size of a whole bitmap isn't known in advance, I couldn't find any fixed type for this bitmap, which pointer can be shifted without casting. IOW, they are variable length.
IMHO it is better to avoid any non-trivial things in generic arch code. Merging those 2 allocations doesn't save any significant bit of memory and might confuse someone. Better just allocate them separately.
Best regards