Re: [libvirt] [RFC: PATCHv4 00/15] outgoing migration via fd: rather than exec:
On 03/11/2011 05:15 AM, Paolo Bonzini wrote:
On 03/11/2011 05:30 AM, Wen Congyang wrote:
>> > Yep, makes sense. I'm double checking whether I reliably closed the
>> > write end of the socket in all paths, and it may boil down to
>> changing
>> > the child to_always_ sendmsg even if there is no fd to send.
>> I'm still
>> > thinking about it.
>
> Using SOCK_STREAM instead of SOCK_DGRAM to create socketpair can
> resolve this
> problem. But I don't know why.
At least with AF_INET that would be obvious: with SOCK_STRAM exiting
the child will close the connection. With a datagram socket, the
parent can still wait for other messages to the same UDP port.
I have no idea whether things work the same for AF_UNIX, but
apparently they do. :)
Not only does this fix the problem, the other uses of socketpair() in
libvirt also use SOCKET_STREAM instead of SOCKET_DGRAM.
So I'd say this is an acceptable fix.