On Wed 26-04-17 16:35:49, Igor Stoppa wrote:
> The bitmasks used for ___GFP_xxx can be defined in terms of an enum,
> which doesn't require manual updates to its values.
GFP masks are rarely updated so why is this worth doing?
> As bonus, __GFP_BITS_SHIFT is automatically kept consistent.
this alone doesn't sound like a huge win to me, to be honest. We already
have ___GFP_$FOO and __GFP_FOO you are adding __GFP_$FOO_SHIFT. This is
too much IMHO.
Also the current mm tree has ___GFP_NOLOCKDEP which is not addressed
here so I suspect you have based your change on the Linus tree.
> Signed-off-by: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
> ---
> include/linux/gfp.h | 82 +++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 55 insertions(+), 27 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 0fe0b62..2f894c5 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -14,33 +14,62 @@ struct vm_area_struct;
> * include/trace/events/mmflags.h and tools/perf/builtin-kmem.c
> */
>
> +enum gfp_bitmask_shift {
> + __GFP_DMA_SHIFT = 0,
> + __GFP_HIGHMEM_SHIFT,
> + __GFP_DMA32_SHIFT,
> + __GFP_MOVABLE_SHIFT,
> + __GFP_RECLAIMABLE_SHIFT,
> + __GFP_HIGH_SHIFT,
> + __GFP_IO_SHIFT,
> + __GFP_FS_SHIFT,
> + __GFP_COLD_SHIFT,
> + __GFP_NOWARN_SHIFT,
> + __GFP_REPEAT_SHIFT,
> + __GFP_NOFAIL_SHIFT,
> + __GFP_NORETRY_SHIFT,
> + __GFP_MEMALLOC_SHIFT,
> + __GFP_COMP_SHIFT,
> + __GFP_ZERO_SHIFT,
> + __GFP_NOMEMALLOC_SHIFT,
> + __GFP_HARDWALL_SHIFT,
> + __GFP_THISNODE_SHIFT,
> + __GFP_ATOMIC_SHIFT,
> + __GFP_ACCOUNT_SHIFT,
> + __GFP_NOTRACK_SHIFT,
> + __GFP_DIRECT_RECLAIM_SHIFT,
> + __GFP_WRITE_SHIFT,
> + __GFP_KSWAPD_RECLAIM_SHIFT,
> + __GFP_BITS_SHIFT
> +};
> +
> +
> /* Plain integer GFP bitmasks. Do not use this directly. */
> -#define ___GFP_DMA 0x01u
> -#define ___GFP_HIGHMEM 0x02u
> -#define ___GFP_DMA32 0x04u
> -#define ___GFP_MOVABLE 0x08u
> -#define ___GFP_RECLAIMABLE 0x10u
> -#define ___GFP_HIGH 0x20u
> -#define ___GFP_IO 0x40u
> -#define ___GFP_FS 0x80u
> -#define ___GFP_COLD 0x100u
> -#define ___GFP_NOWARN 0x200u
> -#define ___GFP_REPEAT 0x400u
> -#define ___GFP_NOFAIL 0x800u
> -#define ___GFP_NORETRY 0x1000u
> -#define ___GFP_MEMALLOC 0x2000u
> -#define ___GFP_COMP 0x4000u
> -#define ___GFP_ZERO 0x8000u
> -#define ___GFP_NOMEMALLOC 0x10000u
> -#define ___GFP_HARDWALL 0x20000u
> -#define ___GFP_THISNODE 0x40000u
> -#define ___GFP_ATOMIC 0x80000u
> -#define ___GFP_ACCOUNT 0x100000u
> -#define ___GFP_NOTRACK 0x200000u
> -#define ___GFP_DIRECT_RECLAIM 0x400000u
> -#define ___GFP_WRITE 0x800000u
> -#define ___GFP_KSWAPD_RECLAIM 0x1000000u
> -/* If the above are modified, __GFP_BITS_SHIFT may need updating */
> +#define ___GFP_DMA (1u << __GFP_DMA_SHIFT)
> +#define ___GFP_HIGHMEM (1u << __GFP_HIGHMEM_SHIFT)
> +#define ___GFP_DMA32 (1u << __GFP_DMA32_SHIFT)
> +#define ___GFP_MOVABLE (1u << __GFP_MOVABLE_SHIFT)
> +#define ___GFP_RECLAIMABLE (1u << __GFP_RECLAIMABLE_SHIFT)
> +#define ___GFP_HIGH (1u << __GFP_HIGH_SHIFT)
> +#define ___GFP_IO (1u << __GFP_IO_SHIFT)
> +#define ___GFP_FS (1u << __GFP_FS_SHIFT)
> +#define ___GFP_COLD (1u << __GFP_COLD_SHIFT)
> +#define ___GFP_NOWARN (1u << __GFP_NOWARN_SHIFT)
> +#define ___GFP_REPEAT (1u << __GFP_REPEAT_SHIFT)
> +#define ___GFP_NOFAIL (1u << __GFP_NOFAIL_SHIFT)
> +#define ___GFP_NORETRY (1u << __GFP_NORETRY_SHIFT)
> +#define ___GFP_MEMALLOC (1u << __GFP_MEMALLOC_SHIFT)
> +#define ___GFP_COMP (1u << __GFP_COMP_SHIFT)
> +#define ___GFP_ZERO (1u << __GFP_ZERO_SHIFT)
> +#define ___GFP_NOMEMALLOC (1u << __GFP_NOMEMALLOC_SHIFT)
> +#define ___GFP_HARDWALL (1u << __GFP_HARDWALL_SHIFT)
> +#define ___GFP_THISNODE (1u << __GFP_THISNODE_SHIFT)
> +#define ___GFP_ATOMIC (1u << __GFP_ATOMIC_SHIFT)
> +#define ___GFP_ACCOUNT (1u << __GFP_ACCOUNT_SHIFT)
> +#define ___GFP_NOTRACK (1u << __GFP_NOTRACK_SHIFT)
> +#define ___GFP_DIRECT_RECLAIM (1u << __GFP_DIRECT_RECLAIM_SHIFT)
> +#define ___GFP_WRITE (1u << __GFP_WRITE_SHIFT)
> +#define ___GFP_KSWAPD_RECLAIM (1u << __GFP_KSWAPD_RECLAIM_SHIFT)
>
> /*
> * Physical address zone modifiers (see linux/mmzone.h - low four bits)
> @@ -180,7 +209,6 @@ struct vm_area_struct;
> #define __GFP_NOTRACK_FALSE_POSITIVE (__GFP_NOTRACK)
>
> /* Room for N __GFP_FOO bits */
> -#define __GFP_BITS_SHIFT 25
> #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
>
> /*
> --
> 2.9.3
>
--
Michal Hocko
SUSE Labs
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