Re: [PATCH v3 net-next 3/5] psp: add a new netdev event for dev unregister

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Wei Wang wrote:
> From: Wei Wang <weibunny@fb.com>
> 
> Add a new netdev event for dev unregister and handle the removal of this
> dev from psp->assoc_dev_list.
> 
> Signed-off-by: Wei Wang <weibunny@fb.com>
> ---
>  net/psp/psp_main.c | 64 +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 63 insertions(+), 1 deletion(-)
> 
> diff --git a/net/psp/psp_main.c b/net/psp/psp_main.c
> index 178b848989f1..8e00ade706e4 100644
> --- a/net/psp/psp_main.c
> +++ b/net/psp/psp_main.c
> @@ -375,10 +375,72 @@ int psp_dev_rcv(struct sk_buff *skb, u16 dev_id, u8 generation, bool strip_icv)
>  }
>  EXPORT_SYMBOL(psp_dev_rcv);
>  
> +static void psp_dev_disassoc_one(struct psp_dev *psd, struct net_device *dev)
> +{
> +	struct psp_assoc_dev *entry, *tmp;
> +
> +	list_for_each_entry_safe(entry, tmp, &psd->assoc_dev_list, dev_list) {
> +		if (entry->assoc_dev == dev) {
> +			list_del(&entry->dev_list);
> +			rcu_assign_pointer(entry->assoc_dev->psp_dev, NULL);
> +			netdev_put(entry->assoc_dev, &entry->dev_tracker);
> +			kfree(entry);
> +			return;
> +		}
> +	}
> +}
> +
> +static int psp_netdev_event(struct notifier_block *nb, unsigned long event,
> +			    void *ptr)
> +{
> +	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
> +	struct psp_dev *psd;
> +
> +	if (event != NETDEV_UNREGISTER)
> +		return NOTIFY_DONE;
> +
> +	rcu_read_lock();
> +	psd = rcu_dereference(dev->psp_dev);
> +	if (psd && psp_dev_tryget(psd)) {
> +		rcu_read_unlock();
> +		mutex_lock(&psd->lock);
> +		psp_dev_disassoc_one(psd, dev);
> +		mutex_unlock(&psd->lock);
> +		psp_dev_put(psd);
> +	} else {
> +		rcu_read_unlock();
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block psp_netdev_notifier = {
> +	.notifier_call = psp_netdev_event,
> +};
> +
>  static int __init psp_init(void)
>  {
> +	int err;
> +
>  	mutex_init(&psp_devs_lock);
> +	err = register_netdevice_notifier(&psp_netdev_notifier);
> +	if (err)
> +		return err;

Defer this until an associated device is actually created?

In many installations it won't be and this notifier won't be needed.
> +
> +	err = genl_register_family(&psp_nl_family);
> +	if (err) {
> +		unregister_netdevice_notifier(&psp_netdev_notifier);
> +		return err;
> +	}
> +
> +	return 0;
> +}