linux-kernel - Re: [PATCH v11 07/10] iommu/vt-d: enable kdump support in iommu module

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Date:	Wed, 13 May 2015 10:36:46 +0800
From:	Baoquan He <bhe@...hat.com>
To:	"Li, ZhenHua" <zhen-hual@...com>
Cc:	dwmw2@...radead.org, indou.takao@...fujitsu.com, joro@...tes.org,
	vgoyal@...hat.com, dyoung@...hat.com,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
	alex.williamson@...hat.com, ddutile@...hat.com,
	ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
	doug.hatch@...com, jerry.hoemann@...com, tom.vaden@...com,
	li.zhang6@...com, lisa.mitchell@...com, billsumnerlinux@...il.com,
	rwright@...com
Subject: Re: [PATCH v11 07/10] iommu/vt-d: enable kdump support in iommu
 module

On 05/13/15 at 10:28am, Li, ZhenHua wrote:
> >>+static u8 g_translation_pre_enabled;
> >Hi Zhenhua,
> >
> >I haven't checked patch one by one, am going through the code flow.
> >
> >About g_translation_pre_enabled, I don't think it's necessary to define
> >it as a global variable. Both its assignment and judgement are in
> >init_dmars(). In this situation a local variable translation_pre_enabled
> >in init_dmars() is enough.
> >
> >You can assign value to it here:
> >
> >		iommu_check_pre_te_status(iommu);
> >		if (iommu->pre_enabled_trans) {
> >			translation_pre_enabled = 1;
> >			...
> >		}
> >
> >Thanks
> >Baoquan
> >
> Hi Baoquan,
> This variable is only be used in this file, for it is defined as static.
> Till now, I think both global and local variable are fine, got the same
> thing.
> But I believe global is better, because if other functions want to
> know whether translation is enabled, this global variable is a good
> choice.

OK, I don't insist on this. But I think we don't have obligation to
consider the future usage for a function or variable. We can often see a
static function is redefined as non-static since it need be used in
other file or the similar thing for variable. It's also good to change
it when it's really needed.

Anyway, I am fine with this. Just for now it's a little uncomfortable to
me.

Thanks
Baoquan
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