On Sat, Feb 28, 2026 at 11:34 PM Jakub Kicinski <[email protected]> wrote: > > On Thu, 26 Feb 2026 10:46:53 -0800 Kiran Kella wrote: > > This is achieved by propagating the psp_dev from the lower device > > to the upper devices in the device stack via a netdevice notifier. > > The lowest device owns the psp_dev pointer while the upper devices > > just borrow the pointer. When the lower device is unlinked, the > > borrowed pointer is cleared in the upper device. > > Assumption being that psp_dev is set on the lowest device before > > any upper devices are stacked on that lowest device. > > As I mentioned in the other thread I'd like to establish some clear > expectation on where psd propagates automatically and where it doesn't. > I don't want to see a stream of patches that say "fix propagating PSP > onto X upper". And conversely report saying "PSP got propagated but > it doesn't actually work" (macvlan in bridge mode etc). > > Hence my preference was to require the user who created the device > to propagate PSP. Willem, WDYT?
I too prefer to go with the single approach where the user has to
propagate the PSP.
>
> > +/**
> > + * psp_clear_upper_dev_psp_dev() - Clear borrowed psp_dev pointer on upper
> > + * device
> > + * @upper_dev: Upper device that may have borrowed psp_dev pointer
> > + * @priv: netdev_nested_priv containing the psp_dev being unregistered
> > + *
> > + * Callback for netdev_walk_all_upper_dev_rcu() to clear borrowed psp_dev
> > + * pointers on upper devices when the underlying psp_dev is being
> > unregistered.
> > + *
> > + * Return: 0 to continue walking, non-zero to stop.
>
> Please (tell your LLM) to avoid adding kdoc which restates what the
> code does. For static function really kdoc is only useful if there's
> something not-obvious to say.
Ack
>
> > +static int psp_clear_upper_dev_psp_dev(struct net_device *upper_dev,
> > + struct netdev_nested_priv *priv)
>
> Please (tell your LLM) that the action goes after the object / noun.
> psp_upper_psp_dev_clear() or some such.
Ack
>
> > +{
> > + struct psp_dev *psd = priv->data;
> > + struct psp_dev *upper_psd;
> > +
> > + upper_psd = rcu_dereference(upper_dev->psp_dev);
> > + if (upper_psd == psd)
> > + rcu_assign_pointer(upper_dev->psp_dev, NULL);
> > +
> > + return 0;
> > +}
> > +
> > /**
> > * psp_dev_unregister() - unregister PSP device
> > * @psd: PSP device structure
> > + *
> > + * Unregisters a PSP device and clears all borrowed psp_dev pointers on
> > + * upper devices (e.g., VLAN subinterfaces) that reference this device.
> > + * This prevents use-after-free if upper devices still have borrowed
> > + * pointers when the psp_dev structure is freed.
> > */
> > void psp_dev_unregister(struct psp_dev *psd)
> > {
> > struct psp_assoc *pas, *next;
> > + struct netdev_nested_priv priv = {
> > + .data = psd,
> > + };
>
> reverse xmas tree
Ack
> --
> pw-bot: cr
smime.p7s
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