Re: [PATCH 2/4] bitmap: unify find_bit operations

[Ulf Hansson <ulf.hansson@linaro.org>]

On Mon, 19 Jul 2021 at 04:18, Yury Norov <yury.norov@gmail.com> wrote:
>
> bitmap_for_each_{set,clear}_region() are similar to for_each_bit()
> macros in include/linux/find.h, but interface and implementation
> of them are different.
>
> This patch adds for_each_bitrange() macros and drops unused
> bitmap_*_region() API in sake of unification.
>
> Signed-off-by: Yury Norov <yury.norov@gmail.com>

Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

Kind regards
Uffe

> ---
>  drivers/mmc/host/renesas_sdhi_core.c |  2 +-
>  include/linux/bitmap.h               | 41 --------------------
>  include/linux/find.h                 | 56 ++++++++++++++++++++++++++++
>  mm/percpu.c                          | 20 ++++------
>  4 files changed, 65 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
> index e49ca0f7fe9a..efd33b1fc467 100644
> --- a/drivers/mmc/host/renesas_sdhi_core.c
> +++ b/drivers/mmc/host/renesas_sdhi_core.c
> @@ -647,7 +647,7 @@ static int renesas_sdhi_select_tuning(struct tmio_mmc_host *host)
>          * is at least SH_MOBILE_SDHI_MIN_TAP_ROW probes long then use the
>          * center index as the tap, otherwise bail out.
>          */
> -       bitmap_for_each_set_region(bitmap, rs, re, 0, taps_size) {
> +       for_each_set_bitrange(rs, re, bitmap, taps_size) {
>                 if (re - rs > tap_cnt) {
>                         tap_end = re;
>                         tap_start = rs;
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index 3f7c6731b203..96670abf49bd 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -55,12 +55,6 @@ struct device;
>   *  bitmap_clear(dst, pos, nbits)               Clear specified bit area
>   *  bitmap_find_next_zero_area(buf, len, pos, n, mask)  Find bit free area
>   *  bitmap_find_next_zero_area_off(buf, len, pos, n, mask, mask_off)  as above
> - *  bitmap_next_clear_region(map, &start, &end, nbits)  Find next clear region
> - *  bitmap_next_set_region(map, &start, &end, nbits)  Find next set region
> - *  bitmap_for_each_clear_region(map, rs, re, start, end)
> - *                                             Iterate over all clear regions
> - *  bitmap_for_each_set_region(map, rs, re, start, end)
> - *                                             Iterate over all set regions
>   *  bitmap_shift_right(dst, src, n, nbits)      *dst = *src >> n
>   *  bitmap_shift_left(dst, src, n, nbits)       *dst = *src << n
>   *  bitmap_cut(dst, src, first, n, nbits)       Cut n bits from first, copy rest
> @@ -459,41 +453,6 @@ static inline void bitmap_replace(unsigned long *dst,
>                 __bitmap_replace(dst, old, new, mask, nbits);
>  }
>
> -static inline void bitmap_next_clear_region(unsigned long *bitmap,
> -                                           unsigned int *rs, unsigned int *re,
> -                                           unsigned int end)
> -{
> -       *rs = find_next_zero_bit(bitmap, end, *rs);
> -       *re = find_next_bit(bitmap, end, *rs + 1);
> -}
> -
> -static inline void bitmap_next_set_region(unsigned long *bitmap,
> -                                         unsigned int *rs, unsigned int *re,
> -                                         unsigned int end)
> -{
> -       *rs = find_next_bit(bitmap, end, *rs);
> -       *re = find_next_zero_bit(bitmap, end, *rs + 1);
> -}
> -
> -/*
> - * Bitmap region iterators.  Iterates over the bitmap between [@start, @end).
> - * @rs and @re should be integer variables and will be set to start and end
> - * index of the current clear or set region.
> - */
> -#define bitmap_for_each_clear_region(bitmap, rs, re, start, end)            \
> -       for ((rs) = (start),                                                 \
> -            bitmap_next_clear_region((bitmap), &(rs), &(re), (end));        \
> -            (rs) < (re);                                                    \
> -            (rs) = (re) + 1,                                                \
> -            bitmap_next_clear_region((bitmap), &(rs), &(re), (end)))
> -
> -#define bitmap_for_each_set_region(bitmap, rs, re, start, end)              \
> -       for ((rs) = (start),                                                 \
> -            bitmap_next_set_region((bitmap), &(rs), &(re), (end));          \
> -            (rs) < (re);                                                    \
> -            (rs) = (re) + 1,                                                \
> -            bitmap_next_set_region((bitmap), &(rs), &(re), (end)))
> -
>  /**
>   * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
>   * @n: u64 value
> diff --git a/include/linux/find.h b/include/linux/find.h
> index ae9ed52b52b8..5bb6db213bcb 100644
> --- a/include/linux/find.h
> +++ b/include/linux/find.h
> @@ -301,6 +301,62 @@ unsigned long find_next_bit_le(const void *addr, unsigned
>              (bit) < (size);                                    \
>              (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
>
> +/**
> + * for_each_set_bitrange - iterate over all set bit ranges [b; e)
> + * @b: bit offset of start of current bitrange (first set bit)
> + * @e: bit offset of end of current bitrange (first unset bit)
> + * @addr: bitmap address to base the search on
> + * @size: bitmap size in number of bits
> + */
> +#define for_each_set_bitrange(b, e, addr, size)                        \
> +       for ((b) = find_next_bit((addr), (size), 0),            \
> +            (e) = find_next_zero_bit((addr), (size), (b) + 1); \
> +            (b) < (size);                                      \
> +            (b) = find_next_bit((addr), (size), (e) + 1),      \
> +            (e) = find_next_zero_bit((addr), (size), (b) + 1))
> +
> +/**
> + * for_each_set_bitrange_from - iterate over set bit ranges [b; e)
> + * @b: bit offset of start of current bitrange (first set bit); must be initialized
> + * @e: bit offset of end of current bitrange (first unset bit)
> + * @addr: bitmap address to base the search on
> + * @size: bitmap size in number of bits
> + */
> +#define for_each_set_bitrange_from(b, e, addr, size)           \
> +       for ((b) = find_next_bit((addr), (size), (b)),          \
> +            (e) = find_next_zero_bit((addr), (size), (b) + 1); \
> +            (b) < (size);                                      \
> +            (b) = find_next_bit((addr), (size), (e) + 1),      \
> +            (e) = find_next_zero_bit((addr), (size), (b) + 1))
> +
> +/**
> + * for_each_clear_bitrange - iterate over all unset bit ranges [b; e)
> + * @b: bit offset of start of current bitrange (first unset bit)
> + * @e: bit offset of end of current bitrange (first set bit)
> + * @addr: bitmap address to base the search on
> + * @size: bitmap size in number of bits
> + */
> +#define for_each_clear_bitrange(b, e, addr, size)              \
> +       for ((b) = find_next_zero_bit((addr), (size), 0),       \
> +            (e) = find_next_bit((addr), (size), (b) + 1);      \
> +            (b) < (size);                                      \
> +            (b) = find_next_zero_bit((addr), (size), (e) + 1), \
> +            (e) = find_next_bit((addr), (size), (b) + 1))
> +
> +/**
> + * for_each_clear_bitrange_from - iterate over unset bit ranges [b; e)
> + * @b: bit offset of start of current bitrange (first unset bit); must be initialized
> + * @e: bit offset of end of current bitrange (first set bit)
> + * @addr: bitmap address to base the search on
> + * @size: bitmap size in number of bits
> + */
> +#define for_each_clear_bitrange_from(b, e, addr, size)         \
> +       for ((b) = find_next_zero_bit((addr), (size), (b)),     \
> +            (e) = find_next_bit((addr), (size), (b) + 1);      \
> +            (b) < (size);                                      \
> +            (b) = find_next_zero_bit((addr), (size), (e) + 1), \
> +            (e) = find_next_bit((addr), (size), (b) + 1))
> +
>  /**
>   * for_each_set_clump8 - iterate over bitmap for each 8-bit clump with set bits
>   * @start: bit offset to start search and to store the current iteration offset
> diff --git a/mm/percpu.c b/mm/percpu.c
> index 25461571dcc5..6d518e822983 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -780,7 +780,7 @@ static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
>  {
>         struct pcpu_block_md *block = chunk->md_blocks + index;
>         unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
> -       unsigned int rs, re, start;     /* region start, region end */
> +       unsigned int start, end;        /* region start, region end */
>
>         /* promote scan_hint to contig_hint */
>         if (block->scan_hint) {
> @@ -796,9 +796,8 @@ static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
>         block->right_free = 0;
>
>         /* iterate over free areas and update the contig hints */
> -       bitmap_for_each_clear_region(alloc_map, rs, re, start,
> -                                    PCPU_BITMAP_BLOCK_BITS)
> -               pcpu_block_update(block, rs, re);
> +       for_each_clear_bitrange_from(start, end, alloc_map, PCPU_BITMAP_BLOCK_BITS)
> +               pcpu_block_update(block, start, end);
>  }
>
>  /**
> @@ -1856,13 +1855,12 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
>
>         /* populate if not all pages are already there */
>         if (!is_atomic) {
> -               unsigned int page_start, page_end, rs, re;
> +               unsigned int page_end, rs, re;
>
> -               page_start = PFN_DOWN(off);
> +               rs = PFN_DOWN(off);
>                 page_end = PFN_UP(off + size);
>
> -               bitmap_for_each_clear_region(chunk->populated, rs, re,
> -                                            page_start, page_end) {
> +               for_each_clear_bitrange_from(rs, re, chunk->populated, page_end) {
>                         WARN_ON(chunk->immutable);
>
>                         ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
> @@ -2018,8 +2016,7 @@ static void pcpu_balance_free(bool empty_only)
>         list_for_each_entry_safe(chunk, next, &to_free, list) {
>                 unsigned int rs, re;
>
> -               bitmap_for_each_set_region(chunk->populated, rs, re, 0,
> -                                          chunk->nr_pages) {
> +               for_each_set_bitrange(rs, re, chunk->populated, chunk->nr_pages) {
>                         pcpu_depopulate_chunk(chunk, rs, re);
>                         spin_lock_irq(&pcpu_lock);
>                         pcpu_chunk_depopulated(chunk, rs, re);
> @@ -2089,8 +2086,7 @@ static void pcpu_balance_populated(void)
>                         continue;
>
>                 /* @chunk can't go away while pcpu_alloc_mutex is held */
> -               bitmap_for_each_clear_region(chunk->populated, rs, re, 0,
> -                                            chunk->nr_pages) {
> +               for_each_clear_bitrange(rs, re, chunk->populated, chunk->nr_pages) {
>                         int nr = min_t(int, re - rs, nr_to_pop);
>
>                         spin_unlock_irq(&pcpu_lock);
> --
> 2.30.2
>