Re: [dpdk-dev] [PATCH v2 1/6] rte_ethdev: add function to check if device is owned

[Thomas Monjalon <thomas@monjalon.net>]

02/04/2020 00:24, Stephen Hemminger:
> On Wed, 01 Apr 2020 23:42:44 +0200
> Thomas Monjalon <thomas@monjalon.net> wrote:
> 
> > 16/03/2020 17:09, Stephen Hemminger:
> > > This is a simple helper function to check if device is owned
> > > (being used as a sub-device).  
> > 
> > I would suggest not restricting ownership to sub-device case.
> > 
> > > It is more convienent than having
> > > applications call rte_eth_dev_owner_get and check the result.  
> > 
> > Yes it is more convenient but I don't like adding such simple wrapper.
> > 
> > I propose to extend rte_eth_dev_owner_get() behaviour:
> > if the owner pointer is NULL, the function returns 0 only
> > if an owner (not RTE_ETH_DEV_NO_OWNER) is found.
> > 
> > So instead of using your wrapper:
> > 	if (rte_eth_dev_is_owned(port_id))
> > you can use:
> > 	if (rte_eth_dev_owner_get(port_id, NULL) == 0)
> 
> That is not how rte_eth_dev_owner_get works now.
> Passing NULL to it would crash.

Indeed this is why I am proposing to extend it
and fill this case.

> And if devices is not owned rte_eth_dev_owner_get() returns 0
> and owner is set to a magic value. We could change the ABI for this 
> since it is marked experimental. But that seems more risky.

This is not an ABI change.
Just manage a case which was crashing previously.