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Date: Wed, 21 Jul 2021 21:12:05 +0000
From: Dennis Zhou <dennis@...nel.org>
To: Yury Norov <yury.norov@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-mmc@...r.kernel.org,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Petr Mladek <pmladek@...e.com>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Tejun Heo <tj@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Wolfram Sang <wsa+renesas@...g-engineering.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Christoph Lameter <cl@...ux.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/4] bitmap: unify find_bit operations
On Sun, Jul 18, 2021 at 07:17:53PM -0700, Yury Norov 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@...il.com>
> ---
> 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
>
Acked-by: Dennis Zhou <dennis@...nel.org>
Thanks,
Dennis
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