linux-kernel - Re: [patch 1/5] x2apic, IR: cleanup X86_X2APIC and INTR

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Date:	Tue, 21 Apr 2009 08:58:41 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	hpa@...or.com, tglx@...utronix.de, linux-kernel@...r.kernel.org,
	dwmw2@...radead.org, Weidong Han <weidong.han@...el.com>
Subject: Re: [patch 1/5] x2apic, IR: cleanup X86_X2APIC and INTR_REMAP
	config checks

* Suresh Siddha <suresh.b.siddha@...el.com> wrote:

> Add x2apic_supported() to cleanup CONFIG_X86_X2APIC checks.
> 
> Fix CONFIG_INTR_REMAP checks.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
> Cc: Weidong Han <weidong.han@...el.com>
> ---
> 
> Index: tip/arch/x86/include/asm/apic.h

Ob'nit'pick: please generate diffstats for future patches as it 
makes in-email review much easier.

The diffstat is:

 arch/x86/include/asm/apic.h          |   10 +++----
 arch/x86/include/asm/io_apic.h       |    2 -
 arch/x86/include/asm/irq_remapping.h |    2 -
 arch/x86/kernel/apic/apic.c          |   49 ++++++++---------------------------
 arch/x86/kernel/apic/io_apic.c       |    2 -
 arch/x86/kernel/apic/probe_64.c      |    2 -
 include/linux/dmar.h                 |    2 +
 7 files changed, 21 insertions(+), 48 deletions(-)

Which already shows that the patch has a very nice cleanup factor.

I've added an "[ Impact: cleanup ]" tag to it - the patch is not 
supposed to have any functional side-effects, right? (i.e. has no 
fixes embedded in it.)

a question:

>  	if (intr_remapping_enabled)
>  		disable_intr_remapping();

Could the intr_remapping_enabled check be moved inside 
disable_intr_remapping(), and thus the ugly 'if (flag)' construct 
could go away?

>  	if (intr_remapping_enabled) {
> +		reenable_intr_remapping(x2apic_mode);
>  		unmask_8259A();
>  		restore_IO_APIC_setup(ioapic_entries);
>  		free_ioapic_entries(ioapic_entries);
>  	}

Ditto - shouldnt this sequence move into reenable_intr_remapping() - 
or into a new helper function? (or is it too single-purpose)

Anyway, this already looks good as-is so i can apply it if you do 
delta patches on top of it to improve it further.

	Ingo
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