Re: [PATCH net 4/8] i40e: Fix XDP program unloading while removing the driver

[Michal Kubiak <michal.kubiak@intel.com>]

On Wed, Jun 05, 2024 at 12:29:57PM -0700, Jakub Kicinski wrote:
> On Wed, 5 Jun 2024 17:00:02 +0200 Michal Kubiak wrote:
> > I am afraid checking for NULL won't be enough here.
> > Normally, when ndo_bpf is called from the user space application, that
> > callback can be called with NULL too (when the user just wants to unload
> > the XDP program). In such a case, apart from calling bpf_prog_put(), we
> > have to rebuild our internal data structures (queues, pointers, counters
> > etc.) to restore the i40e driver working back in normal mode (with no
> > XDP program).
> 
> Apologizes for asking a question which can be answered by studying 
> the code longer, but why do you need to rebuild internal data
> structures for a device which is *down*. Unregistering or not.

Excuse me, but I don't understand why we should assume that a device is
*down* when that callback is being called?
Maybe I didn't make it clear, but the ndo_bpf can be called every time
when the userspace application wants to load or unload the XDP program.
It can happen when a device is *up* and also when the link is *up*.

Michal