RE: [PATCH 4/4] drivers: dma-contiguous: add initialization from device tree

["Joonsoo Kim" <iamjoonsoo.kim@lge.com>]

> -----Original Message-----
> From: Marek Szyprowski [mailto:m.szyprowski@samsung.com]
> Sent: Wednesday, July 02, 2014 7:49 PM
> To: linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linaro-mm-sig@lists.linaro.org; devicetree@vger.kernel.org; linux-
> doc@vger.kernel.org
> Cc: Marek Szyprowski; Benjamin Herrenschmidt; Arnd Bergmann; Michal
> Nazarewicz; Grant Likely; Tomasz Figa; Sascha Hauer; Laura Abbott; Rob
> Herring; Olof Johansson; Pawel Moll; Mark Rutland; Stephen Warren; Ian
> Campbell; Tomasz Figa; Kumar Gala; Nishanth Peethambaran; Marc; Josh
> Cartwright; Catalin Marinas; Will Deacon; Paul Mackerras; Jon Medhurst;
> Joonsoo Kim; Aneesh Kumar K.V.; Andrew Morton
> Subject: [PATCH 4/4] drivers: dma-contiguous: add initialization from
> device tree
> 
> Add a code to create CMA region from reserved memory and add support for
> handling 'shared-dma-pool' reserved-memory device tree nodes.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>  drivers/base/dma-contiguous.c | 67
> +++++++++++++++++++++++++++++++++++++++++
>  include/linux/cma.h           |  3 ++
>  mm/cma.c                      | 69
++++++++++++++++++++++++++++++++-----------
>  3 files changed, 122 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
> index 6606abdf880c..b77ea8bac176 100644
> --- a/drivers/base/dma-contiguous.c
> +++ b/drivers/base/dma-contiguous.c
> @@ -211,3 +211,70 @@ bool dma_release_from_contiguous(struct device *dev,
> struct page *pages,
>  {
>  	return cma_release(dev_get_cma_area(dev), pages, count);
>  }
> +
> +/*
> + * Support for reserved memory regions defined in device tree
> + */
> +#ifdef CONFIG_OF_RESERVED_MEM
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_reserved_mem.h>
> +
> +#undef pr_fmt
> +#define pr_fmt(fmt) fmt
> +
> +static void rmem_cma_device_init(struct reserved_mem *rmem, struct device
> *dev)
> +{
> +	struct cma *cma = rmem->priv;
> +	dev_set_cma_area(dev, cma);
> +}
> +
> +static void rmem_cma_device_release(struct reserved_mem *rmem,
> +				    struct device *dev)
> +{
> +	dev_set_cma_area(dev, NULL);
> +}
> +
> +static const struct reserved_mem_ops rmem_cma_ops = {
> +	.device_init	= rmem_cma_device_init,
> +	.device_release = rmem_cma_device_release,
> +};
> +
> +static int __init rmem_cma_setup(struct reserved_mem *rmem)
> +{
> +	phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1,
> pageblock_order);
> +	phys_addr_t mask = align - 1;
> +	unsigned long node = rmem->fdt_node;
> +	struct cma *cma;
> +	int err;
> +
> +	if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
> +	    of_get_flat_dt_prop(node, "no-map", NULL))
> +		return -EINVAL;
> +
> +	if ((rmem->base & mask) || (rmem->size & mask)) {
> +		pr_err("Reserved memory: incorrect alignment of CMA
> region\n");
> +		return -EINVAL;
> +	}
> +
> +	err = cma_init_reserved_mem(rmem->base, rmem->size, 0, &cma);
> +	if (err) {
> +		pr_err("Reserved memory: unable to setup CMA region\n");
> +		return err;
> +	}
> +	/* Architecture specific contiguous memory fixup. */
> +	dma_contiguous_early_fixup(rmem->base, rmem->size);
> +
> +	if (of_get_flat_dt_prop(node, "linux,cma-default", NULL))
> +		dma_contiguous_set_default(cma);
> +
> +	rmem->ops = &rmem_cma_ops;
> +	rmem->priv = cma;
> +
> +	pr_info("Reserved memory: created CMA memory pool at %pa, size %ld
> MiB\n",
> +		&rmem->base, (unsigned long)rmem->size / SZ_1M);
> +
> +	return 0;
> +}
> +RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
> +#endif
> diff --git a/include/linux/cma.h b/include/linux/cma.h
> index 32cab7a425f9..9a18a2b1934c 100644
> --- a/include/linux/cma.h
> +++ b/include/linux/cma.h
> @@ -16,6 +16,9 @@ extern int __init cma_declare_contiguous(phys_addr_t
> size,
>  			phys_addr_t base, phys_addr_t limit,
>  			phys_addr_t alignment, unsigned int order_per_bit,
>  			bool fixed, struct cma **res_cma);
> +extern int cma_init_reserved_mem(phys_addr_t size,
> +					phys_addr_t base, int order_per_bit,
> +					struct cma **res_cma);
>  extern struct page *cma_alloc(struct cma *cma, int count, unsigned int
> align);
>  extern bool cma_release(struct cma *cma, struct page *pages, int count);
>  #endif
> diff --git a/mm/cma.c b/mm/cma.c
> index 4b251b037e1b..c3d84016d432 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -140,6 +140,54 @@ static int __init cma_init_reserved_areas(void)
>  core_initcall(cma_init_reserved_areas);
> 
>  /**
> + * cma_init_reserved_mem() - create custom contiguous area from reserved
> memory
> + * @base: Base address of the reserved area
> + * @size: Size of the reserved area (in bytes),
> + * @order_per_bit: Order of pages represented by one bit on bitmap.
> + * @res_cma: Pointer to store the created cma region.
> + *
> + * This function creates custom contiguous area from already reserved
> memory.
> + */
> +int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
> +				 int order_per_bit, struct cma **res_cma)
> +{
> +	struct cma *cma;
> +	phys_addr_t alignment;
> +
> +	/* Sanity checks */
> +	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
> +		pr_err("Not enough slots for CMA reserved regions!\n");
> +		return -ENOSPC;
> +	}
> +
> +	if (!size || !memblock_is_region_reserved(base, size))
> +		return -EINVAL;
> +
> +	/* ensure minimal alignment requied by mm core */
> +	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
> +
> +	/* alignment should be aligned with order_per_bit */
> +	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
> +		return -EINVAL;
> +
> +	if (ALIGN(base, alignment) != base || ALIGN(size, alignment) !=
> size)
> +		return -EINVAL;
> +
> +	/*
> +	 * Each reserved area must be initialised later, when more kernel
> +	 * subsystems (like slab allocator) are available.
> +	 */
> +	cma = &cma_areas[cma_area_count];
> +	cma->base_pfn = PFN_DOWN(base);
> +	cma->count = size >> PAGE_SHIFT;
> +	cma->order_per_bit = order_per_bit;
> +	*res_cma = cma;
> +	cma_area_count++;
> +
> +	return 0;
> +}
> +
> +/**
>   * cma_declare_contiguous() - reserve custom contiguous area
>   * @base: Base address of the reserved area optional, use 0 for any
>   * @size: Size of the reserved area (in bytes),
> @@ -162,18 +210,12 @@ int __init cma_declare_contiguous(phys_addr_t base,
>  			phys_addr_t alignment, unsigned int order_per_bit,
>  			bool fixed, struct cma **res_cma)
>  {
> -	struct cma *cma;
> -	int ret = 0;
> +	int ret;
> 
>  	pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n",
>  		__func__, (unsigned long)size, (unsigned long)base,
>  		(unsigned long)limit, (unsigned long)alignment);
> 
> -	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
> -		pr_err("Not enough slots for CMA reserved regions!\n");
> -		return -ENOSPC;
> -	}
> -

Hello, Marek.

After this change, if we have not enough cma_areas, memory will leak.
I think that we need separate function to check constraint and this
function should be called before reserving memory in
cma_declare_contiguous().

BTW, this mail doesn't appear in LKML. What happens? :)

Thanks.