Re: [PATCH net-next v18 03/14] netdev: support binding dma-buf to netdevice

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