linux-kernel - Re: 2.6.28-rc5: unused variable in pagetable

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Message-ID: <20081117082526.GA28786@elte.hu>
Date:	Mon, 17 Nov 2008 09:25:26 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Andrey Borzenkov <arvidjaar@...l.ru>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.28-rc5: unused variable in pagetable_init


* Andrey Borzenkov <arvidjaar@...l.ru> wrote:

>   CC      arch/x86/mm/init_32.o
> /home/bor/src/linux-git/arch/x86/mm/init_32.c: In function ‘pagetable_init’:
> /home/bor/src/linux-git/arch/x86/mm/init_32.c:515: warning: unused variable ‘pgd_base’
> 
> Well, pagetable_init is noop unless HIGHMEM is defined so it could 
> be as simple as that.
> 
> Or is something else expected to go into pagetable_init for more 
> general case?
> 
> --- arch/x86/mm/init_32.c       2008-11-10 06:19:14.000000000 +0300
> +++ /tmp/init_32.c      2008-11-17 06:52:21.383685722 +0300
> @@ -435,9 +435,17 @@ static void __init set_highmem_pages_ini
>  }
>  #endif /* !CONFIG_NUMA */
> 
> +static void __init pagetable_init(void)
> +{
> +       pgd_t *pgd_base = swapper_pg_dir;
> +
> +       permanent_kmaps_init(pgd_base);
> +}
> +
>  #else
>  # define permanent_kmaps_init(pgd_base)                do { } while (0)
>  # define set_highmem_pages_init()      do { } while (0)
> +# define pagetable_init()      do { } while (0)
>  #endif /* CONFIG_HIGHMEM */
> 
>  void __init native_pagetable_setup_start(pgd_t *base)
> @@ -510,13 +518,6 @@ static void __init early_ioremap_page_ta
>         early_ioremap_reset();
>  }
> 
> -static void __init pagetable_init(void)
> -{
> -       pgd_t *pgd_base = swapper_pg_dir;
> -
> -       permanent_kmaps_init(pgd_base);
> -}
> -
>  #ifdef CONFIG_ACPI_SLEEP

The better fix would be to convert permanent_kmaps_init() from a macro 
to an (empty) inline. That way CPP does not eat away the code and GCC 
will known that the variable is indeed used.

	Ingo
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