Re: [dpdk-dev] [RFC] ethdev: complete closing to free all resources

[Thomas Monjalon <thomas@monjalon.net>]

10/09/2018 10:54, Andrew Rybchenko:
> On 09/10/2018 11:42 AM, Thomas Monjalon wrote:
> > 10/09/2018 10:03, Andrew Rybchenko:
> >> On 09/08/2018 02:39 AM, Thomas Monjalon wrote:
> >>> After closing a port, it cannot be restarted.
> >>> So there is no reason to not free all associated resources.
> >>>
> >>> The last step was done with rte_eth_dev_detach() which is deprecated.
> >>> Instead of removing the associated rte_device, the driver should check
> >>> if no more port (ethdev, cryptodev, etc) is still open for the device.
> >>> Then the device resources can be freed by the driver inside the
> >>> dev_close() driver callback operation.
> >>>
> >>> The last ethdev freeing (dev_private and final release), which were done
> >>> by rte_eth_dev_detach(), are now done at the end of rte_eth_dev_close().
> >> For me, it sounds more logical to kill dev_close and keep detach.
> >> IMHO, dev_close is artificial and hardly useful. detach is a local pair
> >> to attach.
> > I don't get your point.
> >
> > In order to free a port, we need close + detach.
> > We can keep only one.
> > I choose close because:
> > 	1) attach/detach are deprecated
> > 	2) probe/close is a more obvious pair
> > 	3) we need the driver to free the lower level resources
> 
> Yes, I'm sorry I used bad terminology.
> We have probe/remove pair for both PCI and vdev drivers and I mean
> that remove is a better candidate to be kept (as a pair for probe which
> allocates all resources).

OK, yes probe/remove is the pair at EAL level.
But if we want to request removal at ethdev level, rte_eth_dev_close
is the function.

Note that there is no function to request creation of an ethdev port.
Adding a new port is done only by the PMD during probing (rte_bus level).