Subject: Re: [PATCH v9 2/5] genalloc:support allocating specific region

From: Scott Wood <[email-masked]>
Date: Thu, 17 Sep 2015 15:19:44 -0500

On Mon, 2015-09-14 at 09:38 +0800, Zhao Qiang wrote:
> Add new algo for genalloc, it reserve a specific region of
> memory matching the size requirement (no alignment constraint)
> 
> Signed-off-by: Zhao Qiang <[email-masked]>
> ---
> Changes for v9:
>       - reserve a specific region, if the return region
>       - is not during the specific region, return fail.
> 
>  include/linux/genalloc.h | 11 +++++++++++
>  lib/genalloc.c           | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
> index aaf3dc2..85e3b2f 100644
> --- a/include/linux/genalloc.h
> +++ b/include/linux/genalloc.h
> @@ -82,6 +82,13 @@ struct genpool_data_align {
>       int align;              /* alignment by bytes for starting address */
>  };
>  
> +/*
> + *  gen_pool data descriptor for gen_pool_fixed_fit.
> + */
> +struct genpool_data_fixed {
> +     unsigned long offset;           /* The offset of the specific region */
> +};
> +
>  extern struct gen_pool *gen_pool_create(int, int);
>  extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned 
> long);
>  extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
> @@ -121,6 +128,10 @@ extern unsigned long gen_pool_first_fit(unsigned long 
> *map, unsigned long size,
>               unsigned long start, unsigned int nr, void *data,
>               struct gen_pool *pool);
>  
> +extern unsigned long gen_pool_fixed_fit(unsigned long *map,
> +             unsigned long size, unsigned long start, unsigned int nr,
> +             void *data, struct gen_pool *pool);
> +

"fixed fit" doesn't make much sense...  How about "fixed_alloc"?

 /**
> + * gen_pool_fixed_fit - reserve a specific region of
> + * matching the size requirement (no alignment constraint)
> + * @map: The address to base the search on
> + * @size: The bitmap size in bits
> + * @start: The bitnumber to start searching at
> + * @nr: The number of zeroed bits we're looking for
> + * @data: data for alignment
> + * @pool: pool to get order from
> + */
> +unsigned long gen_pool_fixed_fit(unsigned long *map, unsigned long size,
> +             unsigned long start, unsigned int nr, void *data,
> +             struct gen_pool *pool)
> +{
> +     struct genpool_data_fixed *fixed_data;
> +     int order;
> +     unsigned long offset_bit;
> +     unsigned long start_bit;
> +
> +     fixed_data = data;
> +     order = pool->min_alloc_order;
> +     offset_bit = fixed_data->offset >> order;
> +     start_bit = bitmap_find_next_zero_area(map, size,
> +                     start + offset_bit, nr, 0);
> +     if (start_bit != offset_bit)
> +             start_bit = size;
> +     return start_bit;
> +}
> +EXPORT_SYMBOL(gen_pool_fixed_fit);

This would be simpler with bitmap_allocate_region().

-Scott