linux-kernel - Re: [PATCH] x86: squash lines for simple wrapper functions

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Date:   Thu, 8 Sep 2016 08:33:59 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     x86@...nel.org, Ingo Molnar <mingo@...hat.com>,
        Toshi Kani <toshi.kani@....com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Borislav Petkov <bp@...e.de>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        "H. Peter Anvin" <hpa@...or.com>, Nathan Zimmer <nzimmer@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Mike Travis <travis@....com>,
        Daniel J Blueman <daniel@...ascale.com>,
        Dimitri Sivanich <sivanich@....com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Hedi Berriche <hedi@....com>,
        Steffen Persvold <sp@...ascale.com>,
        Alex Thorlton <athorlton@....com>,
        Wei Jiangang <weijg.fnst@...fujitsu.com>
Subject: Re: [PATCH] x86: squash lines for simple wrapper functions


* Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:

> Remove unneeded variables and assignments.  I am also removing
> unnecessary parentheses while I am here.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
> 
>  arch/x86/kernel/apic/apic_flat_64.c  | 16 +++-------------
>  arch/x86/kernel/apic/apic_numachip.c |  5 +----
>  arch/x86/kernel/apic/x2apic_uv_x.c   |  5 +----
>  arch/x86/mm/pat_rbtree.c             |  4 +---
>  arch/x86/platform/uv/bios_uv.c       |  7 ++-----
>  arch/x86/platform/uv/tlb_uv.c        |  6 +-----
>  6 files changed, 9 insertions(+), 34 deletions(-)
> 
> diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
> index 5b2ae10..c7228f9 100644
> --- a/arch/x86/kernel/apic/apic_flat_64.c
> +++ b/arch/x86/kernel/apic/apic_flat_64.c
> @@ -116,27 +116,17 @@ static void flat_send_IPI_all(int vector)
>  
>  static unsigned int flat_get_apic_id(unsigned long x)
>  {
> -	unsigned int id;
> -
> -	id = (((x)>>24) & 0xFFu);
> -
> -	return id;
> +	return ((x) >> 24) & 0xFFu;

So while we are removing unnecessary things, exactly why does the 'x' need 
parentheses?

>  static unsigned long set_apic_id(unsigned int id)
>  {
> -	unsigned long x;
> -
> -	x = ((id & 0xFFu)<<24);
> -	return x;
> +	return (id & 0xFFu) << 24;

'id' is already unsigned, why does the 'u' have to be stressed in the literal? 
(Ditto for other places as well)

>  static unsigned long numachip1_set_apic_id(unsigned int id)
>  {
> -	unsigned long x;
> -
> -	x = ((id & 0xffU) << 24);
> -	return x;
> +	return (id & 0xffU) << 24;
>  }

Why is the spelling of the literal inconsistent here with the other patterns?

> +++ b/arch/x86/kernel/apic/x2apic_uv_x.c
> @@ -533,11 +533,8 @@ static unsigned int x2apic_get_apic_id(unsigned long x)
>  
>  static unsigned long set_apic_id(unsigned int id)
>  {
> -	unsigned long x;
> -
>  	/* maskout x2apic_extra_bits ? */
> -	x = id;
> -	return x;
> +	return id;
>  }

This was clearly left there to document a quirk and as a placeholder for future 
changes.

Thanks,

	Ingo