Re: [PATCH v3] net/tap: add queues when attaching from secondary process

[Thomas Monjalon <thomas@monjalon.net>]

20/07/2018 17:35, Wiles, Keith:
> > On Jul 20, 2018, at 4:15 AM, Thomas Monjalon <thomas@monjalon.net> wrote:
> > +	/* FIXME: handle replies.nb_received > 1 */
> 
> I am not a big fan of having TODO or FIXME comments in the code.

What don't you like in such comments?

> Can we remove them and just describe the problem and what would happen
> or not happen if the condition occurs?

You mean describing the problem in the code?

> If we need to add this support in the future then we need to put these
> in a enhancement tracker or someplace else.

The limitation is documented in the guide (limit of 8 queues).

> > +	reply = &replies.msgs[0];

[...]
> > +	/* FIXME: split message if more queues than RTE_MP_MAX_FD_NUM */
> 
> Here too.

This limitation is related to the previous one (send only one message,
receive only message).

> > +	RTE_ASSERT(reply.num_fds <= RTE_MP_MAX_FD_NUM);
> > +
> > +	/* Send reply */
> > +	strcpy(reply.name, request->name);
> > +	strcpy(reply_param->port_name, request_param->port_name);
> 
> Normally we use the snprintf or strlcpy() functions for the above should we do that here too?

Yes it looks to be a good idea.


> > @@ -1946,8 +2056,18 @@ rte_pmd_tap_probe(struct rte_vdev_device *dev)
> > 			TAP_LOG(ERR, "Failed to probe %s", name);
> > 			return -1;
> > 		}
> > -		/* TODO: request info from primary to set up Rx and Tx */
> > 		eth_dev->dev_ops = &ops;
> > +		eth_dev->rx_pkt_burst = pmd_rx_burst;
> > +		eth_dev->tx_pkt_burst = pmd_tx_burst;
> > +
> > +		if (!rte_eal_primary_proc_alive(NULL)) {
> > +			TAP_LOG(ERR, "Primary process is missing");
> > +			return -1;
> > +		}
> > +		ret = tap_mp_attach_queues(name, eth_dev);
> > +		if (ret != 0)
> > +			return -1;
> 
> Does the call above need to be wrapped using if secondary process or is this for both primary and secondary?

It is already in a "secondary only" block.

> > +	/* Register IPC feed callback */
> > +	ret = rte_mp_action_register(TAP_MP_KEY, tap_mp_sync_queues);
> > +	if (ret < 0 && rte_errno != EEXIST) {
> > +		TAP_LOG(ERR, "%s: Failed to register IPC callback: %s",
> > +			tuntap_name, strerror(rte_errno));
> > +		goto leave;
> > +	}
> 
> Same for this one as above?

This code path is executed only in primary or creation of port in secondary.
I think it is fine.

However I am thinking it should be registered only once for all TAP ports.