Re: [dpdk-dev] [PATCH v2] examples/client_server_mp: check port ownership

[Stephen Hemminger <stephen@networkplumber.org>]

On Sun, 7 Jul 2019 05:44:55 +0000
Matan Azrad <matan@mellanox.com> wrote:

> > +	for (count = 0; pm != 0; pm >>= 1, ++count) {
> > +		struct rte_eth_dev_owner owner;
> > +
> > +		if ((pm & 0x1) == 0)
> > +			continue;
> > +
> > +		if (count >= max_ports) {
> > +			printf("WARNING: requested port %u not present -
> > ignoring\n",
> > +				count);
> > +			continue;
> > +		}
> > +		if (rte_eth_dev_owner_get(count, &owner) < 0) {
> > +			printf("ERROR: can not find port %u owner\n",
> > count);  
> 
> What if some entity will take ownership later?
> If you want the app will be ownership aware:
> 	if you sure that you want this port to be owned by this application you need to take ownership on it.
> else:
> the port is hidden by RTE_ETH_FOREACH_DEV if it is owned by some entity. 
> see how it was done in testpmd function: port_id_is_invalid().

There are no mysterious entities in DPDK.
The only thing that can happen later is hotplug, and that will not change state
of existing port.

This model is used for all applications.  The application does not
take ownership, only device drivers do.

The whole portmask as command-line parameter is a bad user experience
now, but that is a different problem.