Re: [PATCH net v2 06/11] netdevsim: add dummy device notifiers

[Jakub Kicinski <kuba@kernel.org>]

On Thu, 27 Mar 2025 06:56:54 -0700 Stanislav Fomichev wrote:
> In order to exercise and verify notifiers' locking assumptions,
> register dummy notifiers and assert that netdev is ops locked
> for REGISTER/UNREGISTER/UP.

> +static int nsim_net_event(struct notifier_block *this, unsigned long event,
> +			  void *ptr)
> +{
> +	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
> +
> +	switch (event) {
> +	case NETDEV_REGISTER:
> +	case NETDEV_UNREGISTER:
> +	case NETDEV_UP:
> +		netdev_ops_assert_locked(dev);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return NOTIFY_DONE;
> +}

Can we register empty notifiers in nsim (just to make sure it has 
a callback) but do the validation in rtnl_net_debug.c
I guess we'd need to transform rtnl_net_debug.c a little,
make it less rtnl specific, compile under DEBUG_NET and ifdef
out the small rtnl parts?

That way we'll have coverage without netdevsim loaded which would 
be all HW testing.