RE: [PATCH 3/3] Xen physical cpus interface

From: Liu, Jinsong
Date: Fri May 11 2012 - 09:12:13 EST

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?


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?

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