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SubjectRe: [RESEND PATCH v2 3/9] asm-generic: Move some macros from linux/bitops.h to a new bits.h file
Hi Andrew,

On Fri, Jul 06, 2018 at 05:30:49PM -0700, Andrew Morton wrote:
> On Tue, 19 Jun 2018 13:53:08 +0100 Will Deacon <will.deacon@arm.com> wrote:
>
> > In preparation for implementing the asm-generic atomic bitops in terms
> > of atomic_long_*, we need to prevent asm/atomic.h implementations from
> > pulling in linux/bitops.h. A common reason for this include is for the
> > BITS_PER_BYTE definition, so move this and some other BIT() and masking
> > macros into a new header file, linux/bits.h
> >
> > --- a/include/linux/bitops.h
> > +++ b/include/linux/bitops.h
> > @@ -2,29 +2,9 @@
> > #ifndef _LINUX_BITOPS_H
> > #define _LINUX_BITOPS_H
> > #include <asm/types.h>
> > +#include <linux/bits.h>
> >
> > -#ifdef __KERNEL__
> > -#define BIT(nr) (1UL << (nr))
> > -#define BIT_ULL(nr) (1ULL << (nr))
> > -#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
> > -#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
> > -#define BIT_ULL_MASK(nr) (1ULL << ((nr) % BITS_PER_LONG_LONG))
> > -#define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG)
> > -#define BITS_PER_BYTE 8
> > #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> > -#endif
>
> Why does it leave BITS_TO_LONGS() in place?
>
> That becomes unfortunate with Chris's patch, so I'm moving
> BITS_TO_LONGS() into bits.h.

The reason I avoided that was because it would pull in the dreaded
kernel.h for DIV_ROUND_UP, and then we're back to circular include hell :(

Will


> From: Chris Wilson <chris@chris-wilson.co.uk>
> Subject: include/linux/bitops.h: introduce BITS_PER_TYPE
>
> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the macro
> to bitops.h, alongside BITS_PER_BYTE, for wider usage.
>
> Link: http://lkml.kernel.org/r/20180706094458.14116-1-chris@chris-wilson.co.uk
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Andy Gospodarek <gospo@broadcom.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> include/linux/bitops.h | 3 ++-
> include/linux/net_dim.h | 1 -
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff -puN include/linux/bitops.h~bitops-introduce-bits_per_type include/linux/bitops.h
> --- a/include/linux/bitops.h~bitops-introduce-bits_per_type
> +++ a/include/linux/bitops.h
> @@ -11,7 +11,8 @@
> #define BIT_ULL_MASK(nr) (1ULL << ((nr) % BITS_PER_LONG_LONG))
> #define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG)
> #define BITS_PER_BYTE 8
> -#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
> +#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
> #endif
>
> /*
> diff -puN include/linux/net_dim.h~bitops-introduce-bits_per_type include/linux/net_dim.h
> --- a/include/linux/net_dim.h~bitops-introduce-bits_per_type
> +++ a/include/linux/net_dim.h
> @@ -363,7 +363,6 @@ static inline void net_dim_sample(u16 ev
> }
>
> #define NET_DIM_NEVENTS 64
> -#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
> #define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))
>
> static inline void net_dim_calc_stats(struct net_dim_sample *start,
> _
>

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