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Message-ID: <xa1ty4rpwbsh.fsf@mina86.com>
Date: Wed, 05 Nov 2014 22:57:34 +0100
From: Michal Nazarewicz <mina86@...a86.com>
To: Gregory Fong <gregory.0xf0@...il.com>, linux-mm@...ck.org
Cc: linux-arm-kernel@...ts.infradead.org, f.fainelli@...il.com,
Michal Nazarewicz <m.nazarewicz@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Gregory Fong <gregory.0xf0@...il.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Andrew Morton <akpm@...ux-foundation.org>,
Jan Kara <jack@...e.cz>, Masanari Iida <standby24x7@...il.com>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] lib: bitmap: Added alignment offset for bitmap_find_next_zero_area()
On Wed, Nov 05 2014, Gregory Fong wrote:
> From: Michal Nazarewicz <m.nazarewicz@...sung.com>
Please change to mina86@...a86.com. My Samsung address is no longer
valid. Ditto on signed-off-by line.
>
> This commit adds a bitmap_find_next_zero_area_off() function which
> works like bitmap_find_next_zero_area() function expect it allows an
> offset to be specified when alignment is checked. This lets caller
> request a bit such that its number plus the offset is aligned
> according to the mask.
>
> Signed-off-by: Michal Nazarewicz <m.nazarewicz@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> CC: Michal Nazarewicz <mina86@...a86.com>
> [gregory.0xf0@...il.com: Retrieved from
> https://patchwork.linuxtv.org/patch/6254/ and updated documentation]
> Signed-off-by: Gregory Fong <gregory.0xf0@...il.com>
> ---
> include/linux/bitmap.h | 36 +++++++++++++++++++++++++++++++-----
> lib/bitmap.c | 24 +++++++++++++-----------
> 2 files changed, 44 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index e1c8d08..34e020c 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -45,6 +45,7 @@
> * bitmap_set(dst, pos, nbits) Set specified bit area
> * 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) as above
> * bitmap_shift_right(dst, src, n, nbits) *dst = *src >> n
> * bitmap_shift_left(dst, src, n, nbits) *dst = *src << n
> * bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
> @@ -114,11 +115,36 @@ extern int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
>
> extern void bitmap_set(unsigned long *map, unsigned int start, int len);
> extern void bitmap_clear(unsigned long *map, unsigned int start, int len);
> -extern unsigned long bitmap_find_next_zero_area(unsigned long *map,
> - unsigned long size,
> - unsigned long start,
> - unsigned int nr,
> - unsigned long align_mask);
> +
> +extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
> + unsigned long size,
> + unsigned long start,
> + unsigned int nr,
> + unsigned long align_mask,
> + unsigned long align_offset);
> +
> +/**
> + * bitmap_find_next_zero_area - find a contiguous aligned zero area
> + * @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
> + * @align_mask: Alignment mask for zero area
> + *
> + * The @align_mask should be one less than a power of 2; the effect is that
> + * the bit offset of all zero areas this function finds is multiples of that
> + * power of 2. A @align_mask of 0 means no alignment is required.
> + */
> +static inline unsigned long
> +bitmap_find_next_zero_area(unsigned long *map,
> + unsigned long size,
> + unsigned long start,
> + unsigned int nr,
> + unsigned long align_mask)
> +{
> + return bitmap_find_next_zero_area_off(map, size, start, nr,
> + align_mask, 0);
> +}
>
> extern int bitmap_scnprintf(char *buf, unsigned int len,
> const unsigned long *src, int nbits);
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index b499ab6..969ae8f 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -326,30 +326,32 @@ void bitmap_clear(unsigned long *map, unsigned int start, int len)
> }
> EXPORT_SYMBOL(bitmap_clear);
>
> -/*
> - * bitmap_find_next_zero_area - find a contiguous aligned zero area
> +/**
> + * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
> * @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
> * @align_mask: Alignment mask for zero area
> + * @align_offset: Alignment offset for zero area.
> *
> * The @align_mask should be one less than a power of 2; the effect is that
> - * the bit offset of all zero areas this function finds is multiples of that
> - * power of 2. A @align_mask of 0 means no alignment is required.
> + * the bit offset of all zero areas this function finds plus @align_offset
> + * is multiple of that power of 2.
> */
> -unsigned long bitmap_find_next_zero_area(unsigned long *map,
> - unsigned long size,
> - unsigned long start,
> - unsigned int nr,
> - unsigned long align_mask)
> +unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
> + unsigned long size,
> + unsigned long start,
> + unsigned int nr,
> + unsigned long align_mask,
> + unsigned long align_offset)
> {
> unsigned long index, end, i;
> again:
> index = find_next_zero_bit(map, size, start);
>
> /* Align allocation */
> - index = __ALIGN_MASK(index, align_mask);
> + index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
>
> end = index + nr;
> if (end > size)
> @@ -361,7 +363,7 @@ again:
> }
> return index;
> }
> -EXPORT_SYMBOL(bitmap_find_next_zero_area);
> +EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
>
> /*
> * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
> --
> 1.9.1
>
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
--
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