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SubjectRe: [PATCH 5/5 v2] x86: PAT: make pat_x_mtrr_type() more readable
On Wed, 18 Jun 2008, Andreas Herrmann wrote:
> And the attached patch makes it even shorter.
> (patch against tip/x86/pat -- where your patch is already residing)

Yes, that's delightful, even better, thanks. After accusing you
of an uninteresting BUG on a fifth value from 2 bits, I had an
inkling that maybe my patch was therefore still stupidly verbose.

> ---
> [PATCH] x86: shrink pat_x_mtrr_type to its essentials
>
> Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>

Acked-by: Hugh Dickins <hugh@veritas.com>

> ---
> arch/x86/mm/pat.c | 30 +++++++++++-------------------
> 1 files changed, 11 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
> index ac3a2b1..227df3c 100644
> --- a/arch/x86/mm/pat.c
> +++ b/arch/x86/mm/pat.c
> @@ -161,29 +161,21 @@ static DEFINE_SPINLOCK(memtype_lock); /* protects memtype list */
> */
> static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type)
> {
> - u8 mtrr_type;
> -
> - /*
> - * We return the PAT request directly for types where PAT takes
> - * precedence with respect to MTRR and for UC_MINUS.
> - * Consistency checks with other PAT requests is done later
> - * while going through memtype list.
> - */
> - if (req_type == _PAGE_CACHE_WC ||
> - req_type == _PAGE_CACHE_UC_MINUS ||
> - req_type == _PAGE_CACHE_UC)
> - return req_type;
> -
> /*
> * Look for MTRR hint to get the effective type in case where PAT
> * request is for WB.
> */
> - mtrr_type = mtrr_type_lookup(start, end);
> - if (mtrr_type == MTRR_TYPE_UNCACHABLE)
> - return _PAGE_CACHE_UC;
> - if (mtrr_type == MTRR_TYPE_WRCOMB)
> - return _PAGE_CACHE_WC;
> - return _PAGE_CACHE_WB;
> + if (req_type == _PAGE_CACHE_WB) {
> + u8 mtrr_type;
> +
> + mtrr_type = mtrr_type_lookup(start, end);
> + if (mtrr_type == MTRR_TYPE_UNCACHABLE)
> + return _PAGE_CACHE_UC;
> + if (mtrr_type == MTRR_TYPE_WRCOMB)
> + return _PAGE_CACHE_WC;
> + }
> +
> + return req_type;
> }
>
> /*


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