On Mon,  5 Aug 2024 21:25:16 +0000 Mina Almasry wrote:

+/* Protected by rtnl_lock() */
+static DEFINE_XARRAY_FLAGS(net_devmem_dmabuf_bindings, XA_FLAGS_ALLOC1);

nit: global variable declarations before any code

+void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
+{
+	struct netdev_rx_queue *rxq;
+	unsigned long xa_idx;
+	unsigned int rxq_idx;
+
+	if (binding->list.next)
+		list_del(&binding->list);
+
+	xa_for_each(&binding->bound_rxqs, xa_idx, rxq) {
+		if (rxq->mp_params.mp_priv == binding) {
+			rxq->mp_params.mp_priv = NULL;
+
+			rxq_idx = get_netdev_rx_queue_index(rxq);
+
+			netdev_rx_queue_restart(binding->dev, rxq_idx);

Throw in a WARN_ON() around this, hopefully we'll get to addressing it
later..

+		}
+	}
+
+	xa_erase(&net_devmem_dmabuf_bindings, binding->id);
+
+	net_devmem_dmabuf_binding_put(binding);
+}
+
+int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
+				    struct net_devmem_dmabuf_binding *binding)
+{
+	struct netdev_rx_queue *rxq;
+	u32 xa_idx;
+	int err;
+
+	if (rxq_idx >= dev->real_num_rx_queues)
+		return -ERANGE;

If we prevent binding to an inactive queue we should also prevent
deactivation.

Please take a look at the (two?) callers of
ethtool_get_max_rxnfc_channel() and ethtool_get_max_rxfh_channel().
Wrap those into a new function for reading max active channel, and
take mp binds into account as well (send the refactor separately 
from the series to avoid making it longer).

+	rxq = __netif_get_rx_queue(dev, rxq_idx);
+	if (rxq->mp_params.mp_priv)
+		return -EEXIST;
+
+	err = xa_alloc(&binding->bound_rxqs, &xa_idx, rxq, xa_limit_32b,
+		       GFP_KERNEL);
+	if (err)
+		return err;
+
+	rxq->mp_params.mp_priv = binding;
+
+	err = netdev_rx_queue_restart(dev, rxq_idx);
+	if (err)
+		goto err_xa_erase;
+
+	return 0;
+
+err_xa_erase:
+	rxq->mp_params.mp_priv = NULL;
+	xa_erase(&binding->bound_rxqs, xa_idx);
+
+	return err;
+}

+void dev_dmabuf_uninstall(struct net_device *dev)
+{
+	unsigned int i, count = dev->num_rx_queues;

nit: why stash the value of num_rx_queues ?

+	struct net_devmem_dmabuf_binding *binding;
+	struct netdev_rx_queue *rxq;
+	unsigned long xa_idx;
+
+	for (i = 0; i < count; i++) {
+		binding = dev->_rx[i].mp_params.mp_priv;
+		if (binding)
+			xa_for_each(&binding->bound_rxqs, xa_idx, rxq)
+				if (rxq == &dev->_rx[i])
+					xa_erase(&binding->bound_rxqs, xa_idx);

nit: Please use "continue", this is too deeply indented

+	nla_for_each_attr_type(attr, NETDEV_A_DMABUF_QUEUES,
+			       genlmsg_data(info->genlhdr),
+			       genlmsg_len(info->genlhdr), rem) {
+		err = nla_parse_nested(
+			tb, ARRAY_SIZE(netdev_queue_id_nl_policy) - 1, attr,
+			netdev_queue_id_nl_policy, info->extack);
+		if (err < 0)
+			goto err_unbind;
+
+		rxq_idx = nla_get_u32(tb[NETDEV_A_QUEUE_ID]);

How do we know this attribute is present?  NL_REQ_ATTR_CHECK()

+		err = net_devmem_bind_dmabuf_to_queue(netdev, rxq_idx, binding);
+		if (err)
+			goto err_unbind;
+	}
+
+	list_add(&binding->list, sock_binding_list);
+
+	nla_put_u32(rsp, NETDEV_A_DMABUF_ID, binding->id);
+	genlmsg_end(rsp, hdr);
+
+	rtnl_unlock();

nit: for symmetry you should also unlock after list_add(),
     netlink msg alloc and prep are before rtnl_lock()

+	return genlmsg_reply(rsp, info);
+
+err_unbind:
+	net_devmem_unbind_dmabuf(binding);
+err_unlock:
+	rtnl_unlock();
+err_genlmsg_free:
+	nlmsg_free(rsp);
+	return err;
 }

+void netdev_nl_sock_priv_init(struct list_head *priv)
+{
+	INIT_LIST_HEAD(priv);
+}
+
+void netdev_nl_sock_priv_destroy(struct list_head *priv)
+{
+	struct net_devmem_dmabuf_binding *binding;
+	struct net_devmem_dmabuf_binding *temp;
+
+	list_for_each_entry_safe(binding, temp, priv, list) {
+		rtnl_lock();
+		net_devmem_unbind_dmabuf(binding);
+		rtnl_unlock();
+	}
+}

nit: move these before the subsys_initcall.. and what it calls