Re: [PATCH] backports: remove obsolete linux/bitops.h header

[Hauke Mehrtens <hauke@hauke-m.de>]

On 11/18/2013 03:26 PM, Stefan Assmann wrote:
> The header seems to be obsolete. Removing it and running devel/ckmake didn't
> reveal any errors. Missing parts can always be re-added in the new
> include_next fashion if necessary.
> 
> Signed-off-by: Stefan Assmann <sassmann@kpanic.de>

Some of these functions are needed, because they are not provided by old
kernel versions.

> ---
>  backport/backport-include/linux/bitops.h | 211 -------------------------------
>  1 file changed, 211 deletions(-)
>  delete mode 100644 backport/backport-include/linux/bitops.h
> 
> diff --git a/backport/backport-include/linux/bitops.h b/backport/backport-include/linux/bitops.h
> deleted file mode 100644
> index aa76af1..0000000
> --- a/backport/backport-include/linux/bitops.h
> +++ /dev/null
> @@ -1,211 +0,0 @@
> -#ifndef _LINUX_BITOPS_H
> -#define _LINUX_BITOPS_H
> -#include <asm/types.h>
> -
> -#ifdef	__KERNEL__
> -#define BIT(nr)			(1UL << (nr))
> -#define BIT_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
> -#define BIT_WORD(nr)		((nr) / BITS_PER_LONG)
> -#define BITS_PER_BYTE		8
> -#ifndef BITS_TO_LONGS /* Older kernels define this already */
> -#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> -#endif
> -#endif
> -
> -extern unsigned int __sw_hweight8(unsigned int w);
> -extern unsigned int __sw_hweight16(unsigned int w);
> -extern unsigned int __sw_hweight32(unsigned int w);
> -extern unsigned long __sw_hweight64(__u64 w);
> -
> -/*
> - * Include this here because some architectures need generic_ffs/fls in
> - * scope
> - */
> -#include <asm/bitops.h>
> -
> -#define for_each_set_bit(bit, addr, size) \
> -	for ((bit) = find_first_bit((addr), (size)); \
> -	     (bit) < (size); \
> -	     (bit) = find_next_bit((addr), (size), (bit) + 1))

for_each_set_bit was added in kernel 2.6.34 and it is used by iwlwifi.

> -
> -static __inline__ int get_bitmask_order(unsigned int count)
> -{
> -	int order;
> -
> -	order = fls(count);
> -	return order;	/* We could be slightly more clever with -1 here... */
> -}
> -
> -static __inline__ int get_count_order(unsigned int count)
> -{
> -	int order;
> -
> -	order = fls(count) - 1;
> -	if (count & (count - 1))
> -		order++;
> -	return order;
> -}
> -
> -static inline unsigned long hweight_long(unsigned long w)
> -{
> -	return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
> -}
> -
> -/**
> - * rol32 - rotate a 32-bit value left
> - * @word: value to rotate
> - * @shift: bits to roll
> - */
> -static inline __u32 rol32(__u32 word, unsigned int shift)
> -{
> -	return (word << shift) | (word >> (32 - shift));
> -}
> -
> -/**
> - * ror32 - rotate a 32-bit value right
> - * @word: value to rotate
> - * @shift: bits to roll
> - */
> -static inline __u32 ror32(__u32 word, unsigned int shift)
> -{
> -	return (word >> shift) | (word << (32 - shift));
> -}
> -
> -/**
> - * rol16 - rotate a 16-bit value left
> - * @word: value to rotate
> - * @shift: bits to roll
> - */
> -static inline __u16 rol16(__u16 word, unsigned int shift)
> -{
> -	return (word << shift) | (word >> (16 - shift));
> -}
> -
> -/**
> - * ror16 - rotate a 16-bit value right
> - * @word: value to rotate
> - * @shift: bits to roll
> - */
> -static inline __u16 ror16(__u16 word, unsigned int shift)
> -{
> -	return (word >> shift) | (word << (16 - shift));
> -}
> -
> -/**
> - * rol8 - rotate an 8-bit value left
> - * @word: value to rotate
> - * @shift: bits to roll
> - */
> -static inline __u8 rol8(__u8 word, unsigned int shift)
> -{
> -	return (word << shift) | (word >> (8 - shift));
> -}
> -
> -/**
> - * ror8 - rotate an 8-bit value right
> - * @word: value to rotate
> - * @shift: bits to roll
> - */
> -static inline __u8 ror8(__u8 word, unsigned int shift)
> -{
> -	return (word >> shift) | (word << (8 - shift));
> -}
> -
> -/**
> - * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
> - * @value: value to sign extend
> - * @index: 0 based bit index (0<=index<32) to sign bit
> - */
> -static inline __s32 sign_extend32(__u32 value, int index)
> -{
> -	__u8 shift = 31 - index;
> -	return (__s32)(value << shift) >> shift;
> -}

sign_extend32 was added in kernel 2.6.38, and we have to backport it
because iwlegacy, ath5k and probably more are using it.

> -
> -static inline unsigned fls_long(unsigned long l)
> -{
> -	if (sizeof(l) == 4)
> -		return fls(l);
> -	return fls64(l);
> -}
> -
> -/**
> - * __ffs64 - find first set bit in a 64 bit word
> - * @word: The 64 bit word
> - *
> - * On 64 bit arches this is a synomyn for __ffs
> - * The result is not defined if no bits are set, so check that @word
> - * is non-zero before calling this.
> - */
> -static inline unsigned long __ffs64(u64 word)
> -{
> -#if BITS_PER_LONG == 32
> -	if (((u32)word) == 0UL)
> -		return __ffs((u32)(word >> 32)) + 32;
> -#elif BITS_PER_LONG != 64
> -#error BITS_PER_LONG not 32 or 64
> -#endif
> -	return __ffs((unsigned long)word);
> -}

__ffs64 was added in kernel 2.6.30 and it is used by mac80211

> -
> -#ifdef __KERNEL__
> -#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
> -
> -/**
> - * find_first_bit - find the first set bit in a memory region
> - * @addr: The address to start the search at
> - * @size: The maximum size to search
> - *
> - * Returns the bit number of the first set bit.
> - */
> -extern unsigned long find_first_bit(const unsigned long *addr,
> -				    unsigned long size);
> -
> -/**
> - * find_first_zero_bit - find the first cleared bit in a memory region
> - * @addr: The address to start the search at
> - * @size: The maximum size to search
> - *
> - * Returns the bit number of the first cleared bit.
> - */
> -extern unsigned long find_first_zero_bit(const unsigned long *addr,
> -					 unsigned long size);
> -#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
> -
> -#ifdef CONFIG_GENERIC_FIND_LAST_BIT
> -/**
> - * find_last_bit - find the last set bit in a memory region
> - * @addr: The address to start the search at
> - * @size: The maximum size to search
> - *
> - * Returns the bit number of the first set bit, or size.
> - */
> -extern unsigned long find_last_bit(const unsigned long *addr,
> -				   unsigned long size);
> -#endif /* CONFIG_GENERIC_FIND_LAST_BIT */
> -
> -#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
> -
> -/**
> - * find_next_bit - find the next set bit in a memory region
> - * @addr: The address to base the search on
> - * @offset: The bitnumber to start searching at
> - * @size: The bitmap size in bits
> - */
> -extern unsigned long find_next_bit(const unsigned long *addr,
> -				   unsigned long size, unsigned long offset);
> -
> -/**
> - * find_next_zero_bit - find the next cleared bit in a memory region
> - * @addr: The address to base the search on
> - * @offset: The bitnumber to start searching at
> - * @size: The bitmap size in bits
> - */
> -
> -extern unsigned long find_next_zero_bit(const unsigned long *addr,
> -					unsigned long size,
> -					unsigned long offset);
> -
> -#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
> -#endif /* __KERNEL__ */
> -#endif
>