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SubjectRe: [PATCHv4 5/5] arm64: Add atomic pool for non-coherent and CMA allocations.
On Wed, Jul 02, 2014 at 11:03:38AM -0700, Laura Abbott wrote:
[...]
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
[...]
> +static struct gen_pool *atomic_pool;
> +
> +#define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K
> +static size_t atomic_pool_size = DEFAULT_DMA_COHERENT_POOL_SIZE;

There doesn't seem to be much use for this since it can't be overridden
via init_dma_coherent_pool_size like on ARM.

> +static int __free_from_pool(void *start, size_t size)
> +{
> + if (!__in_atomic_pool(start, size))
> + return 0;
> +
> + gen_pool_free(atomic_pool, (unsigned long)start, size);
> +
> + return 1;
> +}
> +
> +

There's a gratuituous blank line here.

> static void *__dma_alloc_coherent(struct device *dev, size_t size,
> dma_addr_t *dma_handle, gfp_t flags,
> struct dma_attrs *attrs)
> @@ -53,7 +103,8 @@ static void *__dma_alloc_coherent(struct device *dev, size_t size,
> if (IS_ENABLED(CONFIG_ZONE_DMA) &&
> dev->coherent_dma_mask <= DMA_BIT_MASK(32))
> flags |= GFP_DMA;
> - if (IS_ENABLED(CONFIG_DMA_CMA)) {
> +
> + if (!(flags & __GFP_WAIT) && IS_ENABLED(CONFIG_DMA_CMA)) {

I think the diff would be more readable here if this wasn't introducing
a blank linke and kept the IS_ENABLED() first.

> struct page *page;
>
> size = PAGE_ALIGN(size);
> @@ -73,50 +124,56 @@ static void __dma_free_coherent(struct device *dev, size_t size,
> void *vaddr, dma_addr_t dma_handle,
> struct dma_attrs *attrs)
> {
> + bool freed;
> + phys_addr_t paddr = dma_to_phys(dev, dma_handle);
> +
> if (dev == NULL) {
> WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
> return;
> }
>
> - if (IS_ENABLED(CONFIG_DMA_CMA)) {
> - phys_addr_t paddr = dma_to_phys(dev, dma_handle);
>
> - dma_release_from_contiguous(dev,

The above leaves an unnecessary blank line in place.

> ptr = __dma_alloc_coherent(dev, size, dma_handle, flags, attrs);
> if (!ptr)
> goto no_mem;
> - map = kmalloc(sizeof(struct page *) << order, flags & ~GFP_DMA);
> - if (!map)
> - goto no_map;
>
> /* remove any dirty cache lines on the kernel alias */
> __dma_flush_range(ptr, ptr + size);
>
> +

Adds an unnecessary blank line.

> @@ -332,6 +391,67 @@ static struct notifier_block amba_bus_nb = {
>
> extern int swiotlb_late_init_with_default_size(size_t default_size);
>
> +static int __init atomic_pool_init(void)
> +{
> + pgprot_t prot = __pgprot(PROT_NORMAL_NC);
> + unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
> + struct page *page;
> + void *addr;
> +
> +

There's another gratuituous blank line here...

> + if (dev_get_cma_area(NULL))
> + page = dma_alloc_from_contiguous(NULL, nr_pages,
> + get_order(atomic_pool_size));
> + else
> + page = alloc_pages(GFP_KERNEL, get_order(atomic_pool_size));
> +
> +

and here.

> + if (page) {
> + int ret;
> +
> + atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
> + if (!atomic_pool)
> + goto free_page;
> +
> + addr = dma_common_contiguous_remap(page, atomic_pool_size,
> + VM_USERMAP, prot, atomic_pool_init);
> +
> + if (!addr)
> + goto destroy_genpool;
> +
> + memset(addr, 0, atomic_pool_size);
> + __dma_flush_range(addr, addr + atomic_pool_size);
> +
> + ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
> + page_to_phys(page),
> + atomic_pool_size, -1);
> + if (ret)
> + goto remove_mapping;
> +
> + gen_pool_set_algo(atomic_pool,
> + gen_pool_first_fit_order_align, NULL);
> +
> + pr_info("DMA: preallocated %zd KiB pool for atomic allocations\n",

I think this should be "%zu" because atomic_pool_size is a size_t, not a
ssize_t.

> + atomic_pool_size / 1024);
> + return 0;
> + }
> + goto out;
> +
> +remove_mapping:
> + dma_common_free_remap(addr, atomic_pool_size, VM_USERMAP);
> +destroy_genpool:
> + gen_pool_destroy(atomic_pool);
> + atomic_pool == NULL;

This probably doesn't belong here.

> +free_page:
> + if (!dma_release_from_contiguous(NULL, page, nr_pages))
> + __free_pages(page, get_order(atomic_pool_size));

You use get_order(atomic_pool_size) a lot, perhaps it should be a
temporary variable?

> +out:
> + pr_err("DMA: failed to allocate %zx KiB pool for atomic coherent allocation\n",
> + atomic_pool_size / 1024);

Print in decimal rather than hexadecimal?

Thierry
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