Re: [PATCH v3] net/vhost: fix segfault when creating vdev dynamically

["Chen, Junjie J" <junjie.j.chen@intel.com>]

Thanks for report, I just summited this patch to fix:
https://dpdk.org/dev/patchwork/patch/37765/ 

> 
> Hi,
> 
> On Fri, Mar 30, 2018 at 02:58:31PM +0800, Junjie Chen wrote:
> >When creating vdev dynamically, vhost pmd driver starts directly
> >without checking TX/RX queues are ready or not, and thus causes
> >segmentation fault when vhost library accesses queues. This patch adds
> >a flag to check whether queues are setup or not, and adds queues setup
> >into dev_start function to allow user to start them after setting up.
> 
> for me, with this patch vhost enqueue/dequeue code is never called because
> 
>   if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
> 
> this check in eth_vhost_rx() is always true.
> 
> When I revert this patch it works as usual.
> 
> My testpmd cmdline is:
> 
> gdb --args $RTE_SDK/install/bin/testpmd -l 0,2,3,4,5 --socket-mem=1024 -n 4 \
>     --vdev 'net_vhost0,iface=/tmp/vhost-user1' \
>     --vdev 'net_vhost1,iface=/tmp/vhost-user2' -- \
>     --portmask=f  --rxq=1 --txq=1 \
>     --nb-cores=4 --forward-mode=io  -i
> 
> After starting testpmd I issue commands "set portlist 0,2,1,3", start my guest
> and start another testpmd issue in the guest.
> 
> Another problem I see: Before this patch I could start testpmd, issue the
> portlist command and type "start". If I do this now I get an infinite loop of
> "VHOST CONFIG device not found" messages.
> 
> 
> regards,
> Jens