Re: [PATCH bpf v2] xdp: fix hang while unregistering device bound to xdp socket

[Jakub Kicinski]

On Fri,  7 Jun 2019 20:31:43 +0300, Ilya Maximets wrote:
> +static int xsk_notifier(struct notifier_block *this,
> +			unsigned long msg, void *ptr)
> +{
> +	struct sock *sk;
> +	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
> +	struct net *net = dev_net(dev);
> +	int i, unregister_count = 0;

Please order the var declaration lines longest to shortest.
(reverse christmas tree)

> +	mutex_lock(&net->xdp.lock);
> +	sk_for_each(sk, &net->xdp.list) {
> +		struct xdp_sock *xs = xdp_sk(sk);
> +
> +		mutex_lock(&xs->mutex);
> +		switch (msg) {
> +		case NETDEV_UNREGISTER:

You should probably check the msg type earlier and not take all the
locks and iterate for other types..