udp_tunnel: add the ability to share port tables

Unfortunately recent Intel NIC designs share the UDP port table
across netdevs. So far the UDP tunnel port state was maintained
per netdev, we need to extend that to cater to Intel NICs.

Expect NICs to allocate the info structure dynamically and link
to the state from there. All the shared NICs will record port
offload information in the one instance of the table so we need
to make sure that the use count can accommodate larger numbers.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 94bb7a882250..2ea453dac876 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h
@@ -200,11 +200,27 @@ enum udp_tunnel_nic_info_flags {
 	UDP_TUNNEL_NIC_INFO_STATIC_IANA_VXLAN	= BIT(3),
 };
 
+struct udp_tunnel_nic;
+
+#define UDP_TUNNEL_NIC_MAX_SHARING_DEVICES	(U16_MAX / 2)
+
+struct udp_tunnel_nic_shared {
+	struct udp_tunnel_nic *udp_tunnel_nic_info;
+
+	struct list_head devices;
+};
+
+struct udp_tunnel_nic_shared_node {
+	struct net_device *dev;
+	struct list_head list;
+};
+
 /**
  * struct udp_tunnel_nic_info - driver UDP tunnel offload information
  * @set_port:	callback for adding a new port
  * @unset_port:	callback for removing a port
  * @sync_table:	callback for syncing the entire port table at once
+ * @shared:	reference to device global state (optional)
  * @flags:	device flags from enum udp_tunnel_nic_info_flags
  * @tables:	UDP port tables this device has
  * @tables.n_entries:		number of entries in this table
@@ -213,6 +229,12 @@ enum udp_tunnel_nic_info_flags {
  * Drivers are expected to provide either @set_port and @unset_port callbacks
  * or the @sync_table callback. Callbacks are invoked with rtnl lock held.
  *
+ * Devices which (misguidedly) share the UDP tunnel port table across multiple
+ * netdevs should allocate an instance of struct udp_tunnel_nic_shared and
+ * point @shared at it.
+ * There must never be more than %UDP_TUNNEL_NIC_MAX_SHARING_DEVICES devices
+ * sharing a table.
+ *
  * Known limitations:
  *  - UDP tunnel port notifications are fundamentally best-effort -
  *    it is likely the driver will both see skbs which use a UDP tunnel port,
@@ -234,6 +256,8 @@ struct udp_tunnel_nic_info {
 	/* all at once */
 	int (*sync_table)(struct net_device *dev, unsigned int table);
 
+	struct udp_tunnel_nic_shared *shared;
+
 	unsigned int flags;
 
 	struct udp_tunnel_nic_table_info {