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Date: Thu, 11 Mar 2010 09:08:03 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] Re: [PATCH 1/7] Add support for generic notifier
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To: Avi Kivity <avi@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, Paul Brook <paul@codesourcery.com>, Paolo Bonzini <pbonzini@redhat.com>, Gerd Hoffman <kraxel@redhat.com>

On 03/11/2010 08:42 AM, Avi Kivity wrote:
> On 03/11/2010 04:36 PM, Paolo Bonzini wrote:
>> On 03/11/2010 02:42 PM, Avi Kivity wrote:
>>> On 03/11/2010 03:25 PM, Paolo Bonzini wrote:
>>>> I didn't understand the advantage of making QEMUNotifier a
>>>> struct. Instead of using container_of, reusing QEMUBHFunc (renamed to
>>>> QEMUCallbackFunc maybe?) in QEMUNotifierNode [...]
>>>> seems cleaner. You would place the QEMUNotifierNode in VncState in
>>>> order to do the removal later.
>>>
>>> I disagree. container_of() is both a little more type safe, and removes
>>> the need for an extra pointer and memory object.
>> > The caller will almost always have an object in which to embed the
>> > notifier, best to make use of it.
>>
>> It doesn't remove the need for an extra memory object.  Anthony's 
>> design embeds the Notifier but not the NotifierNode.  Indeed, my 
>> design does have an extra pointer (in the NotifierNode, which grows 
>> from 3 to 4 words).
>
> Right.  Well, it should.

It's certainly possible (and reasonable) to stick the QTAIL_NODE() into 
QEMUNotifier.

Regards,

Anthony Liguori

>> I still don't like container_of much, but maybe I'll grow my 
>> appreciation of it with time. :-)
>
> Or grow your dislike of void pointers.
>