Re: [PATCH net-next] netdevsim: Register and unregister devlink traps on probe/remove device

[Edwin Peer]

On Sun, Oct 24, 2021 at 3:35 PM Ido Schimmel <idosch@xxxxxxxxxx> wrote:

> On Sun, Oct 24, 2021 at 11:42:11AM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@xxxxxxxxxx>
> >
> > Align netdevsim to be like all other physical devices that register and
> > unregister devlink traps during their probe and removal respectively.
>
> No, this is incorrect. Out of the three drivers that support both reload
> and traps, both netdevsim and mlxsw unregister the traps during reload.
> Here is another report from syzkaller about mlxsw [1].
>
> Please revert both 22849b5ea595 ("devlink: Remove not-executed trap
> policer notifications") and 8bbeed485823 ("devlink: Remove not-executed
> trap group notifications").

Could we also revert 82465bec3e97 ("devlink: Delete reload
enable/disable interface")? This interface is needed because bnxt_en
cannot reorder devlink last. If Leon had fully carried out the
re-ordering in our driver he would have introduced a udev
phys_port_name regression because of:

cda2cab0771 ("bnxt_en: Move devlink_register before registering netdev")

and:

ab178b058c4 ("bnxt: remove ndo_get_phys_port_name implementation")

I think this went unnoticed for bnxt_en, because Michael had not yet
posted our devlink reload patches, which presently rely on the reload
enable/disable API. Absent horrible kludges in reload down/up which
currently depends on the netdev, there doesn't appear to be a clean
way to resolve the circular dependency without the interlocks this API
provides.

I imagine other subtle regressions are lying in wait.

Regards,
Edwin Peer