Re: [Qemu-devel] [vhost-user BUG ?] QEMU process segfault when shutdown or reboot with vhost-user

[zhanghailiang]

On 2015/11/3 22:54, Marc-André Lureau wrote:
> Hi
>
> On Tue, Nov 3, 2015 at 2:01 PM, zhanghailiang
> <address@hidden> wrote:
> > The corresponding codes where gdb reports error are: (We have added some
> > codes in net.c)
>
> Can you reproduce with unmodified qemu? Could you give instructions to do so?

OK, i will try to do it. There is nothing special, we run iperf tool in VM,
and then shutdown or reboot it. There is change you can catch segfault.

> > ssize_t qemu_deliver_packet(NetClientState *sender,
> >                              unsigned flags,
> >                              const uint8_t *data,
> >                              size_t size,
> >                              void *opaque)
> > {
> >      NetClientState *nc = opaque;
> >      ssize_t ret;
> >
> >      if (nc->link_down) {
> >          return size;
> >      }
> >
> >      if (nc->receive_disabled) {
> >          return 0;
> >      }
> >
> >      if (flags & QEMU_NET_PACKET_FLAG_RAW && nc->info->receive_raw) {
> >          ret = nc->info->receive_raw(nc, data, size);
> >      } else {
> >          ret = nc->info->receive(nc, data, size);   ----> Here is 510 line
> >      }
> >
> > I'm not quite familiar with vhost-user, but for vhost-user, these two
> > callback functions seem to be always NULL,
> > Why we can come here ?
>
> You should not come here, vhost-user has nc->receive_disabled (it
> changes in 2.5)

I have looked at the newest codes, i think we can still have chance to
come here, since we will change nc->receive_disable to false temporarily in
qemu_flush_or_purge_queued_packets(), there is no difference between 2.3 and 2.5
for this.
Besides, is it possible for !QTAILQ_EMPTY(&queue->packets) to be true
in qemu_net_queue_flush() for vhost-user ?

i will try to reproduce it by using newest qemu.

Thanks,
zhanghailiang