wt., 23 cze 2020 o 00:49 Jakub Kicinski [off-list ref] napisał(a):

On Mon, 22 Jun 2020 12:00:48 +0200 Bartosz Golaszewski wrote:

quoted

From: Bartosz Golaszewski <redacted>

This devres helper registers a release callback that only unregisters
the net_device. It works perfectly fine with netdev structs that are
not managed on their own. There's no reason to check this - drop the
warning.

Signed-off-by: Bartosz Golaszewski <redacted>

I think the reasoning for this suggestion was to catch possible UAF
errors. The netdev doesn't necessarily has to be from devm_alloc_*
but it has to be part of devm-ed memory or memory which is freed
after driver's remove callback.

Yes I understand that UAF was the concern here, but this limitation is
unnecessary. In its current form devm_register_netdev() only works for
struct net_device allocated with devm_alloc_etherdev(). Meanwhile
calling alloc_netdev() (which doesn't have its devm counterpart yet -
I may look into it shortly), then registering a devm action with
devm_add_action_or_reset() which would free this memory is a perfectly
fine use case. This patch would make it possible.

Are there cases in practice where you've seen the netdev not being
devm allocated?

As I said above - alloc_netdev() used by wireless, can, usb etc.
drivers doesn't have a devres variant.

Bartosz