Re: [dpdk-dev] [PATCH v2 2/4] ethdev: add siblings iterators

[Thomas Monjalon <thomas@monjalon.net>]

27/02/2019 11:07, Gaëtan Rivet:
> Hi Thomas,
> 
> On Wed, Feb 20, 2019 at 11:10:49PM +0100, Thomas Monjalon wrote:
> > If multiple ports share the same hardware device (rte_device),
> > they are siblings and can be found thanks to the new functions
> > and loop macros.
> > One iterator takes a port id as reference,
> > while the other one directly refers to the parent device.
> > 
> > The ownership is not checked because siblings may have
> > different owners.
> > 
> > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > ---
> >  lib/librte_ethdev/rte_ethdev.c           | 20 +++++++++++
> >  lib/librte_ethdev/rte_ethdev.h           | 46 ++++++++++++++++++++++++
> >  lib/librte_ethdev/rte_ethdev_version.map |  2 ++
> >  3 files changed, 68 insertions(+)
> > 
> > diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> > index b3b2fb1dba..42154787f8 100644
> > --- a/lib/librte_ethdev/rte_ethdev.c
> > +++ b/lib/librte_ethdev/rte_ethdev.c
> > @@ -340,6 +340,26 @@ rte_eth_find_next(uint16_t port_id)
> >  	return port_id;
> >  }
> >  
> > +uint16_t __rte_experimental
> > +rte_eth_find_next_of(uint16_t port_id, const struct rte_device *parent)
> > +{
> > +	while (port_id < RTE_MAX_ETHPORTS &&
> > +			rte_eth_devices[port_id].state == RTE_ETH_DEV_UNUSED &&
> > +			rte_eth_devices[port_id].device != parent)
> > +		port_id++;
> 
> Why not call rte_eth_find_next directly from this function, and
> add your specific test on top of it?
> 
> Something like:
> 
>     	while (port_id < RTE_MAX_ETHPORTS &&
>     	       rte_eth_devices[port_id].device != parent)
>     		port_id = rte_eth_find_next(port_id + 1);
> 
> this way you won't have to rewrite the test on the device state. Having the
> logic expressed in several places would make reworking the device states more
> complicated than necessary if it were to happen (just as you did when switching
> the test from !(ATTACHED || REMOVED) to (UNUSED).

About the intent, you are right.
About the solution, it seems buggy. We can try to find another way
of coding this loop by using rte_eth_find_next()
and adding the parent condition.