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Message-ID: <36ca99e90809070055u3b3b8415i2a5dbfb6bf617d35@mail.gmail.com>
Date: Sun, 7 Sep 2008 09:55:17 +0200
From: "Bert Wesarg" <bert.wesarg@googlemail.com>
To: "Mike Travis" <travis@sgi.com>
Subject: Re: [RFC 11/13] genapic: reduce stack pressuge in io_apic.c step 3 target_cpus
Cc: "Ingo Molnar" <mingo@elte.hu>, "Andrew Morton" <akpm@linux-foundation.org>,
       davej@codemonkey.org.uk, "David Miller" <davem@davemloft.net>,
       "Eric Dumazet" <dada1@cosmosbay.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       "Jack Steiner" <steiner@sgi.com>,
       "Jeremy Fitzhardinge" <jeremy@goop.org>, "Jes Sorensen" <jes@sgi.com>,
       "H. Peter Anvin" <hpa@zytor.com>,
       "Thomas Gleixner" <tglx@linutronix.de>, linux-kernel@vger.kernel.org
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On Sun, Sep 7, 2008 at 01:50, Mike Travis <travis@sgi.com> wrote:
>  * Step 3 "target_cpus" of cleaning up io_apic.c modifies the TARGET_CPUS
>    interface to pass a pointer to the returned mask for arch X86_64,
>    removing yet another "cpumask_t variable on the stack".
>
>        target_cpus = TARGET_CPUS;
>
>    becomes:
>
>        TARGET_CPUS(target_cpus);
>
>    For x86_32 this is expanded to:
>
>        target_cpus = (genapic->target_cpus());
>
>    For x86_64 this is expanded to:
>
>        target_cpus = (genapic->target_cpus)(&(target_cpus));
But its expended to:
         (genapic->target_cpus)(&(target_cpus));

> -#define TARGET_CPUS      (genapic->target_cpus())
> +#define TARGET_CPUS(retval) (genapic->target_cpus)(&(retval))


> +#ifdef CONFIG_X86_64
> +#define TARGET_CPUS(retval)      (genapic->target_cpus)(&(retval))
> +#else
> +#define TARGET_CPUS(retval)      retval = (genapic->target_cpus())
> +#endif

Bert