Re: qemu couldn't connect the unix domain socket

[Stefano Brivio <sbrivio@redhat.com>]

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Hi Feng Li,

On Thu, 28 Oct 2021 12:25:29 +0800
Li Feng <fengli(a)smartx.com> wrote:

> Add cc.

Sorry, I missed your email. It looks like on Mailman3, if I'm the owner
of a list, I'm not automatically a member receiving posts from the list
itself -- added myself as member, too.

> On Tue, Oct 26, 2021 at 1:28 PM Li Feng <fengli(a)smartx.com> wrote:
> >
> > Hi,
> > I just tested the master code, the passt just exited without any error.
> >
> > ```
> > $ ./passt
> > Outbound interface: ens192
> > ARP:
> >     address: 00:50:56:be:9d:1f
> > DHCP:
> >     assign: 192.168.64.217
> >     mask: 255.255.240.0
> >     router: 192.168.64.1
> >         search:
> >             .
> > UNIX domain socket bound at /tmp/passt_1.socket
> >
> > You can now start qrap:
> >     ./qrap 5 kvm ... -net socket,fd=5 -net nic,model=virtio
> > or directly qemu, patched with:
> >     qemu/0001-net-Allow-also-UNIX-domain-sockets-to-be-used-as-net.patch
> > as follows:
> >     kvm ... -net socket,connect=/tmp/passt_1.socket -net nic,model=virtio
> > 21-10-26 13:23:43 root(a)192.168.64.217:~/passt(master✗)

passt will fork into background as soon as it gets a connection. Can
you retry running it as:

	./passt -f -d

so we can see if something strange is going on (-f stands for
--foreground, -d for --debug)? Because:

> > ```
> > Another terminal:
> > ```
> > $ bash x.sh
> > recv: Connection reset by peer
> > Probe of /tmp/passt_1.socket failed
> > connect: No such file or directory
> > Probe of /tmp/passt_2.socket failed
> > connect: No such file or directory
> > Probe of /tmp/passt_3.socket failed
> > ...
> > ```

...well, this shouldn't happen. It's probing /tmp/passt_1.socket and
failing to get an answer.

This just happened to another user, in that case seccomp was
terminating passt because on his system daemon() called a different set
of syscalls compared to my system:

	https://passt.top/passt/commit/?id=1fc6416cf9446cbf75818fd61772610e74709065

and I expect some more issues like these at the beginning, I didn't
test it on different distributions yet.

By the way, I'm working on adding tests for a few distributions right
now, so that we can catch those early.

-- 
Stefano