linux-kernel - RE: [PATCH 3/3] Xen physical cpus interface

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Date:	Fri, 11 May 2012 13:12:13 +0000
From:	"Liu, Jinsong" <jinsong.liu@...el.com>
To:	'Konrad Rzeszutek Wilk' <konrad.wilk@...cle.com>
CC:	"'xen-devel@...ts.xensource.com'" <xen-devel@...ts.xensource.com>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 3/3] Xen physical cpus interface

Liu, Jinsong wrote:
> Just notice your reply (so quick :)
> 
> Agree and will update later, except 1 concern below.
> 
> Konrad Rzeszutek Wilk wrote:
>>> 
>>> Hmm, it's good if it's convenient to do it automatically via
>>> dev->release. However, dev container (pcpu) would be free at some
>>> other error cases, so I prefer do it 'manually'.
>> 
>> You could also call pcpu_release(..) to do it manually.
>> 
> 
> that means kfree(pcpu) would be done twice at some error cases, do
> you think it really good? 
> 

Ping.

I think error recovery should be kept inside error logic level itself, if try to recover upper level error would bring trouble.

In our example, there are 2 logic levels:
pcpu level (as container), and dev level (subfield used for sys)
dev->release should only recover error occurred at dev/sys level, and the pcpu error should be recovered at pcpu level.

If dev->release try to recover its container pcpu level error, like list_del/kfree(pcpu), it would make confusing. i.e., considering pcpu_sys_create(), 2 error cases:
device_register fail, and device_create_file fail --> how can the caller decide kfree(pcpu) or not?

So how about recover pcpu error manually and explicitly?

Thanks,
Jinsong--
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