[libvirt] [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd

[Corey Bryant]

On 06/26/2012 04:50 PM, Luiz Capitulino wrote:
> On Tue, 26 Jun 2012 13:45:52 +0200
> Kevin Wolf <kwolf at redhat.com> wrote:
>
>> Am 26.06.2012 11:10, schrieb Daniel P. Berrange:
>>> I was thinking about some of the sources complexity when using
>>> FD passing from libvirt and wanted to raise one idea for discussion
>>> before we continue.
>>>
>>> With this proposed series, we have usage akin to:
>>>
>>>    1. pass_fd FDSET={M} -> returns a string "/dev/fd/N" showing QEMU's
>>>       view of the FD
>>>    2. drive_add file=/dev/fd/N
>>>    3. if failure:
>>>         close_fd "/dev/fd/N"
>>
>> In fact, there are more steps:
>>
>> 4. use it successfully
>> 5. close_fd "/dev/fd/N"
>>
>> I think it would well be possible that qemu just closes the fd when it's
>> not used internally any more.
>
> pass-fd could have a flag indicating qemu to do that.
>

It seems like libvirt would be in a better position to understand when a 
file is no longer in use, and then it can call close_fd.  No?  Of course 
the the only fd that needs to be closed is the originally passed fd. 
The dup'd fd's are closed by QEMU.

-- 
Regards,
Corey