From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B93B9475; Wed, 2 Oct 2024 14:49:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880545; cv=none; b=ASO4+KATlUytorlffBQAJVanIw/XmQH/YonBBvEqVnQd1oWHBGdbeI/EaIICce/EV7GvgVLkWBH5kwXgGXWD3a/OUmFihJj+adsMSnEFu/+5KbNVYZbLC8AoS+KJXHrTgQfQpa52CSo7v3OV4QWP9RUsZHmP19lWl+ENb1IJznw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880545; c=relaxed/simple; bh=2ZGVH5u9bGxffknAm4x1w3632T1V/rEADPzNgcJJHGk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qxCLKmRHy+1mVRoec/MdF4BTkew0YgiW0H7sszKAu+BR96Z91SScqNmw+vZX4UHpjyIOYWLB7IO6c49tpha+culjpGQUcf/zFoKEsUfapcOuWY8xF3gVH7uzcaB227ie9bMHbsQNr4fhR3z9rVi6wsiepSdixeHEXgfFPvs9flg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ASWjrJC7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ASWjrJC7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A296C4CEC2; Wed, 2 Oct 2024 14:49:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727880545; bh=2ZGVH5u9bGxffknAm4x1w3632T1V/rEADPzNgcJJHGk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ASWjrJC7WEz1VMhW49KAQIf4NtiRyCTy9w1kESGS7aAUHPpTMAmLS3Ih8JBxBqaZc d/JGYjRFlgBJzd9oNY+u6MrHCde02IP6uJFB48lnWd6SJ4oe9zGGgj6GVkHhitMujA SH6pF1q18B1zcViTTYqL4JxuijC/sJY1Lu5g3xsE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Arnd Bergmann , Syed Nayyar Waris , William Breathitt Gray , Yury Norov , Alexander Potapenko , Andy Shevchenko , Alexander Lobakin , "David S. Miller" , Sasha Levin Subject: [PATCH 6.6 495/538] lib/bitmap: add bitmap_{read,write}() Date: Wed, 2 Oct 2024 15:02:14 +0200 Message-ID: <20241002125811.979384170@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125751.964700919@linuxfoundation.org> References: <20241002125751.964700919@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Syed Nayyar Waris [ Upstream commit 63c15822b8dd02a2423cfd92232245ace3f7a11b ] The two new functions allow reading/writing values of length up to BITS_PER_LONG bits at arbitrary position in the bitmap. The code was taken from "bitops: Introduce the for_each_set_clump macro" by Syed Nayyar Waris with a number of changes and simplifications: - instead of using roundup(), which adds an unnecessary dependency on , we calculate space as BITS_PER_LONG-offset; - indentation is reduced by not using else-clauses (suggested by checkpatch for bitmap_get_value()); - bitmap_get_value()/bitmap_set_value() are renamed to bitmap_read() and bitmap_write(); - some redundant computations are omitted. Cc: Arnd Bergmann Signed-off-by: Syed Nayyar Waris Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/lkml/fe12eedf3666f4af5138de0e70b67a07c7f40338.1592224129.git.syednwaris@gmail.com/ Suggested-by: Yury Norov Co-developed-by: Alexander Potapenko Signed-off-by: Alexander Potapenko Reviewed-by: Andy Shevchenko Acked-by: Yury Norov Signed-off-by: Yury Norov Signed-off-by: Alexander Lobakin Signed-off-by: David S. Miller Stable-dep-of: 77b0b98bb743 ("btrfs: subpage: fix the bitmap dump which can cause bitmap corruption") Signed-off-by: Sasha Levin --- include/linux/bitmap.h | 77 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 3c8d2b87a9edc..729ec2453149f 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -77,6 +77,10 @@ struct device; * bitmap_to_arr64(buf, src, nbits) Copy nbits from buf to u64[] dst * bitmap_get_value8(map, start) Get 8bit value from map at start * bitmap_set_value8(map, value, start) Set 8bit value to map at start + * bitmap_read(map, start, nbits) Read an nbits-sized value from + * map at start + * bitmap_write(map, value, start, nbits) Write an nbits-sized value to + * map at start * * Note, bitmap_zero() and bitmap_fill() operate over the region of * unsigned longs, that is, bits behind bitmap till the unsigned long @@ -613,6 +617,79 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value, map[index] |= value << offset; } +/** + * bitmap_read - read a value of n-bits from the memory region + * @map: address to the bitmap memory region + * @start: bit offset of the n-bit value + * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG + * + * Returns: value of @nbits bits located at the @start bit offset within the + * @map memory region. For @nbits = 0 and @nbits > BITS_PER_LONG the return + * value is undefined. + */ +static inline unsigned long bitmap_read(const unsigned long *map, + unsigned long start, + unsigned long nbits) +{ + size_t index = BIT_WORD(start); + unsigned long offset = start % BITS_PER_LONG; + unsigned long space = BITS_PER_LONG - offset; + unsigned long value_low, value_high; + + if (unlikely(!nbits || nbits > BITS_PER_LONG)) + return 0; + + if (space >= nbits) + return (map[index] >> offset) & BITMAP_LAST_WORD_MASK(nbits); + + value_low = map[index] & BITMAP_FIRST_WORD_MASK(start); + value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits); + return (value_low >> offset) | (value_high << space); +} + +/** + * bitmap_write - write n-bit value within a memory region + * @map: address to the bitmap memory region + * @value: value to write, clamped to nbits + * @start: bit offset of the n-bit value + * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG. + * + * bitmap_write() behaves as-if implemented as @nbits calls of __assign_bit(), + * i.e. bits beyond @nbits are ignored: + * + * for (bit = 0; bit < nbits; bit++) + * __assign_bit(start + bit, bitmap, val & BIT(bit)); + * + * For @nbits == 0 and @nbits > BITS_PER_LONG no writes are performed. + */ +static inline void bitmap_write(unsigned long *map, unsigned long value, + unsigned long start, unsigned long nbits) +{ + size_t index; + unsigned long offset; + unsigned long space; + unsigned long mask; + bool fit; + + if (unlikely(!nbits || nbits > BITS_PER_LONG)) + return; + + mask = BITMAP_LAST_WORD_MASK(nbits); + value &= mask; + offset = start % BITS_PER_LONG; + space = BITS_PER_LONG - offset; + fit = space >= nbits; + index = BIT_WORD(start); + + map[index] &= (fit ? (~(mask << offset)) : ~BITMAP_FIRST_WORD_MASK(start)); + map[index] |= value << offset; + if (fit) + return; + + map[index + 1] &= BITMAP_FIRST_WORD_MASK(start + nbits); + map[index + 1] |= (value >> space); +} + #endif /* __ASSEMBLY__ */ #endif /* __LINUX_BITMAP_H */ -- 2.43.0