net: Add lease info to queue-get response

Populate nested lease info to the queue-get response that returns the
ifindex, queue id with type and optionally netns id if the device
resides in a different netns.

Example with ynl client when using AF_XDP via queue leasing:

  # ip a
  [...]
  4: enp10s0f0np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 xdp/id:24 qdisc mq state UP group default qlen 1000
    link/ether e8:eb:d3:a3:43:f6 brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.2/24 scope global enp10s0f0np0
       valid_lft forever preferred_lft forever
    inet6 fe80::eaeb:d3ff:fea3:43f6/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
  [...]

  # ethtool -i enp10s0f0np0
  driver: mlx5_core
  [...]

  # ynl --family netdev --output-json --do queue-get \
        --json '{"ifindex": 4, "id": 15, "type": "rx"}'
  {'id': 15,
   'ifindex': 4,
   'lease': {'ifindex': 8, 'netns-id': 0, 'queue': {'id': 1, 'type': 'rx'}},
   'napi-id': 8227,
   'type': 'rx',
   'xsk': {}}

  # ip netns list
  foo (id: 0)

  # ip netns exec foo ip a
  [...]
  8: nk@NONE: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
      link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
      inet6 fe80::200:ff:fe00:0/64 scope link proto kernel_ll
         valid_lft forever preferred_lft forever
  [...]

  # ip netns exec foo ethtool -i nk
  driver: netkit
  [...]

  # ip netns exec foo ls /sys/class/net/nk/queues/
  rx-0  rx-1  tx-0

  # ip netns exec foo ynl --family netdev --output-json --do queue-get \
        --json '{"ifindex": 8, "id": 1, "type": "rx"}'
  {"id": 1, "type": "rx", "ifindex": 8, "xsk": {}}

Note that the caller of netdev_nl_queue_fill_one() holds the netdevice
lock. For the queue-get we do not lock both devices. When queues get
{un,}leased, both devices are locked, thus if __netif_get_rx_queue_lease()
returns a lease pointer, it points to a valid device. The netns-id is
fetched via peernet2id_alloc() similarly as done in OVS.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Co-developed-by: David Wei <dw@davidwei.uk>
Signed-off-by: David Wei <dw@davidwei.uk>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260402231031.447597-4-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index a1f23c2c96d4..a4d8cad6db74 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -41,6 +41,60 @@ bool netif_rxq_is_leased(struct net_device *dev, unsigned int rxq_idx)
 	return false;
 }
 
+/* Virtual devices eligible for leasing have no dev->dev.parent, while
+ * physical devices always have one. Use this to enforce the correct
+ * lease traversal direction.
+ */
+static bool netif_lease_dir_ok(const struct net_device *dev,
+			       enum netif_lease_dir dir)
+{
+	if (dir == NETIF_VIRT_TO_PHYS && !dev->dev.parent)
+		return true;
+	if (dir == NETIF_PHYS_TO_VIRT && dev->dev.parent)
+		return true;
+	return false;
+}
+
+struct netdev_rx_queue *
+__netif_get_rx_queue_lease(struct net_device **dev, unsigned int *rxq_idx,
+			   enum netif_lease_dir dir)
+{
+	struct net_device *orig_dev = *dev;
+	struct netdev_rx_queue *rxq = __netif_get_rx_queue(orig_dev, *rxq_idx);
+
+	if (rxq->lease) {
+		if (!netif_lease_dir_ok(orig_dev, dir))
+			return NULL;
+		rxq = rxq->lease;
+		*rxq_idx = get_netdev_rx_queue_index(rxq);
+		*dev = rxq->dev;
+	}
+	return rxq;
+}
+
+struct netdev_rx_queue *
+netif_get_rx_queue_lease_locked(struct net_device **dev, unsigned int *rxq_idx)
+{
+	struct net_device *orig_dev = *dev;
+	struct netdev_rx_queue *rxq;
+
+	/* Locking order is always from the virtual to the physical device
+	 * see netdev_nl_queue_create_doit().
+	 */
+	netdev_ops_assert_locked(orig_dev);
+	rxq = __netif_get_rx_queue_lease(dev, rxq_idx, NETIF_VIRT_TO_PHYS);
+	if (rxq && orig_dev != *dev)
+		netdev_lock(*dev);
+	return rxq;
+}
+
+void netif_put_rx_queue_lease_locked(struct net_device *orig_dev,
+				     struct net_device *dev)
+{
+	if (orig_dev != dev)
+		netdev_unlock(dev);
+}
+
 /* See also page_pool_is_unreadable() */
 bool netif_rxq_has_unreadable_mp(struct net_device *dev, unsigned int rxq_idx)
 {