linux-kernel - Re: [PATCH v5 07/12] x86/apic: Unify interrupt mode setup for UP system

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Message-ID: <adbe8114-45b9-2869-3906-a9c5745eb749@cn.fujitsu.com>
Date:   Mon, 3 Jul 2017 10:34:40 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <xen-devel@...ts.xenproject.org>, <mingo@...nel.org>,
        <hpa@...or.com>, <ebiederm@...ssion.com>, <bhe@...hat.com>,
        <boris.ostrovsky@...cle.com>, <peterz@...radead.org>,
        <izumi.taku@...fujitsu.com>
Subject: Re: [PATCH v5 07/12] x86/apic: Unify interrupt mode setup for UP
 system

Hi Thomas,

At 07/03/2017 02:19 AM, Thomas Gleixner wrote:
> On Fri, 30 Jun 2017, Dou Liyang wrote:
>>  static inline int apic_force_enable(unsigned long addr)
>> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
>> index 0601054..9bf7e95 100644
>> --- a/arch/x86/kernel/apic/apic.c
>> +++ b/arch/x86/kernel/apic/apic.c
>> @@ -1198,6 +1198,10 @@ static int __init apic_intr_mode_select(int *upmode)
>>  	}
>>  #endif
>>
>> +#ifdef CONFIG_UP_LATE_INIT
>> +	*upmode = true;
>> +#endif
>
> This is really wrong. The upmode decision, which is required for calling
> apic_bsp_setup() should not happen here, really. As I told you in the
> previous patch, use the return code and then you can make further decisions
> in apic_intr_mode_init().

Really thanks for your detail explaining, I learned more than i read
from books about the programming skill.

>
> And you do it there w/o any ifdeffery:
>
> static void apic_intr_mode_init(void)
> {
> 	bool upmode = IS_ENABLED(CONFIG_UP_LATE_INIT);
>
> 	switch (....) {
> 	case XXXX:
> 		upmode = true;
> 		....
> 	}
> 	apic_bsp_setup(upmode);
> }

This looks more beautiful than mine.  I will use it in the next version.

Thanks,

	dou.

>
> Thanks,
>
> 	tglx
>
>
>