Re: [Qemu-devel] [PATCH v8 16/54] Return path: Open a return path on QEMUFile for sockets

[Daniel P. Berrange]

On Tue, Sep 29, 2015 at 09:37:40AM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
> 
> Postcopy needs a method to send messages from the destination back to
> the source, this is the 'return path'.
> 
> Wire it up for 'socket' QEMUFile's.

I find this to be a pretty wierd approach to the problem. THe underlying
transport is bi-directional, so I would expect to have a single QEMUFile
object that allowed bi-directional I/O on it, rather than creating a
second QEMUFile for the back channel, which was forbidden from closing
the shared FD.

I can understand why you've done this though - since we only have a
single buffer embedded in QEMUFile.  I wonder though if we'd be better
off changing QEMUFile to have a 'inbuf' and 'outbuf' intead of just
'buf' and likewise iniov & outiov. Then we can allow bi-directional
I/O on the single QEMUFile object which is a more natural fit.

Regards,
Daniel
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