Re: [dpdk-dev] [PATCH] net/vhost: fix segfault when creating vdev dynamically

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

Hi Jianfeng

> On 3/28/2018 12:05 AM, Junjie Chen wrote:
> > when creating vdev dynamically, vhost pmd driver start directly
> > without checking TX/RX queues ready or not, and thus cause
> > segmentation fault when vhost library accessing queues. This patch add
> > flag to check whether queues setup or not, and add driver start call
> > into dev_start to allow user start it after setting up queue.
> 
> The issue is clear now. But this patch just puts the situation before below fix:
> "it doesn't create the actual datagram socket until you call .dev_start()."

No, if the queue exist, the datagram socket still get created in vhost_create API, since the vhost_driver_register still exist in vhost_create.

> 
> To fix this issue, we might delay the queue setup until we really have queues?
> 
> > Fixes: aed0b12930b33("net/vhost: fix socket file deleted on stop")
> 
> Missed the space between commit number and title. And we keep 12
> characters for the commit id.

Thanks for reminder, will update in v2.
> 
> Thanks,
> Jianfeng
> 
> > Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
> > ---
> >   drivers/net/vhost/rte_eth_vhost.c | 21 +++++++++++++++++++--
> >   1 file changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/vhost/rte_eth_vhost.c
> > b/drivers/net/vhost/rte_eth_vhost.c
> > index 3aae01c..719a150 100644
> > --- a/drivers/net/vhost/rte_eth_vhost.c
> > +++ b/drivers/net/vhost/rte_eth_vhost.c
> > @@ -118,6 +118,7 @@ struct pmd_internal {
> >   	char *iface_name;
> >   	uint16_t max_queues;
> >   	rte_atomic32_t started;
> > +	rte_atomic32_t once;
> >   };
> >
> >   struct internal_list {
> > @@ -772,12 +773,24 @@ rte_eth_vhost_get_vid_from_port_id(uint16_t
> port_id)
> >   static int
> >   eth_dev_start(struct rte_eth_dev *dev)
> >   {
> > +	int ret = 0;
> >   	struct pmd_internal *internal = dev->data->dev_private;
> >
> > +	if (unlikely(rte_atomic32_read(&internal->once) == 0)) {
> > +		ret = rte_vhost_driver_start(internal->iface_name);
> > +		if (ret < 0) {
> > +			RTE_LOG(ERR, PMD, "Failed to start driver for %s\n",
> > +				internal->iface_name);
> > +			return ret;
> > +		}
> > +
> > +		rte_atomic32_set(&internal->once, 1);
> > +	}
> > +
> >   	rte_atomic32_set(&internal->started, 1);
> >   	update_queuing_status(dev);
> >
> > -	return 0;
> > +	return ret;
> >   }
> >
> >   static void
> > @@ -1101,7 +1114,11 @@ eth_dev_vhost_create(struct rte_vdev_device
> *dev, char *iface_name,
> >   		goto error;
> >   	}
> >
> > -	if (rte_vhost_driver_start(iface_name) < 0) {
> > +	if (!data->rx_queues || !data->tx_queues) {
> > +		RTE_LOG(INFO, PMD,
> > +			"TX/RX queue is not ready, driver will not start\n");
> > +		rte_atomic32_set(&internal->once, 0);
> > +	} else if (rte_vhost_driver_start(iface_name) < 0) {
> >   		RTE_LOG(ERR, PMD, "Failed to start driver for %s\n",
> >   			iface_name);
> >   		goto error;