xsk: Proxy pool management for leased queues

Similarly to the net_mp_{open,close}_rxq handling for leased queues, proxy
the xsk_{reg,clear}_pool_at_qid via netif_get_rx_queue_lease_locked such
that in case a virtual netdev picked a leased rxq, the request gets through
to the real rxq in the physical netdev. The proxying is only relevant for
queue_id < dev->real_num_rx_queues since right now its only supported for
rxqs.

Signed-off-by: Daniel Borkmann <[email protected]>
Co-developed-by: David Wei <[email protected]>
Signed-off-by: David Wei <[email protected]>
Acked-by: Stanislav Fomichev <[email protected]>
Reviewed-by: Nikolay Aleksandrov <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

net/xdp/xsk.c

@@ -23,6 +23,8 @@
 #include <linux/netdevice.h>
 #include <linux/rculist.h>
 #include <linux/vmalloc.h>
+
+#include <net/netdev_queues.h>
 #include <net/xdp_sock_drv.h>
 #include <net/busy_poll.h>
 #include <net/netdev_lock.h>
@@ -117,10 +119,18 @@ EXPORT_SYMBOL(xsk_get_pool_from_qid);
 
 void xsk_clear_pool_at_qid(struct net_device *dev, u16 queue_id)
 {
-	if (queue_id < dev->num_rx_queues)
-		dev->_rx[queue_id].pool = NULL;
-	if (queue_id < dev->num_tx_queues)
-		dev->_tx[queue_id].pool = NULL;
+	struct net_device *orig_dev = dev;
+	unsigned int id = queue_id;
+
+	if (id < dev->real_num_rx_queues)
+		WARN_ON_ONCE(!netif_get_rx_queue_lease_locked(&dev, &id));
+
+	if (id < dev->real_num_rx_queues)
+		dev->_rx[id].pool = NULL;
+	if (id < dev->real_num_tx_queues)
+		dev->_tx[id].pool = NULL;
+
+	netif_put_rx_queue_lease_locked(orig_dev, dev);
 }
 
 /* The buffer pool is stored both in the _rx struct and the _tx struct as we do
@@ -130,17 +140,29 @@ void xsk_clear_pool_at_qid(struct net_device *dev, u16 queue_id)
 int xsk_reg_pool_at_qid(struct net_device *dev, struct xsk_buff_pool *pool,
 			u16 queue_id)
 {
-	if (queue_id >= max_t(unsigned int,
-			      dev->real_num_rx_queues,
-			      dev->real_num_tx_queues))
+	struct net_device *orig_dev = dev;
+	unsigned int id = queue_id;
+	int ret = 0;
+
+	if (id >= max(dev->real_num_rx_queues,
+		      dev->real_num_tx_queues))
 		return -EINVAL;
+	if (id < dev->real_num_rx_queues) {
+		if (!netif_get_rx_queue_lease_locked(&dev, &id))
+			return -EBUSY;
+		if (xsk_get_pool_from_qid(dev, id)) {
+			ret = -EBUSY;
+			goto out;
+		}
+	}
 
-	if (queue_id < dev->real_num_rx_queues)
-		dev->_rx[queue_id].pool = pool;
-	if (queue_id < dev->real_num_tx_queues)
-		dev->_tx[queue_id].pool = pool;
-
-	return 0;
+	if (id < dev->real_num_rx_queues)
+		dev->_rx[id].pool = pool;
+	if (id < dev->real_num_tx_queues)
+		dev->_tx[id].pool = pool;
+out:
+	netif_put_rx_queue_lease_locked(orig_dev, dev);
+	return ret;
 }
 
 static int __xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff_xsk *xskb, u32 len,