STRUCT UDP_TUNNEL_NIC_INFO(9)

🌸 NAME 🌸

struct udp_tunnel_nic_info — the driver-side tea on UDP tunnel offload info 💅 (straight out of the Kernel API Manual, bestie, this is the real deal ✨)

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✨ SYNOPSIS ✨

struct udp_tunnel_nic_info {
    int (*set_port)(struct net_device *dev, unsigned int table, unsigned int entry, struct udp_tunnel_info *ti);
    int (*unset_port)(struct net_device *dev, unsigned int table, unsigned int entry, struct udp_tunnel_info *ti);
    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 {
      unsigned int n_entries;
      unsigned int tunnel_types;
    } tables[UDP_TUNNEL_NIC_MAX_TABLES];
 };

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🎀 MEMBERS 🎀

okay so here's the whole cast, no skips, iykyk 👑

• set_port — the callback that adds a new port 🫶
• unset_port — the callback that removes a port 🙈
• sync_table — the callback that syncs the entire port table all at once, one big slay 🔥
• shared — a reference to device global state, and it's optional (so lowkey you can skip it) 💜
• flags — device flags, and they come from enum udp_tunnel_nic_info_flags ⭐
• tables — the UDP port tables this device has 🎀
• tables.n_entries — how many entries live in this table, literally the count 💅
• tables.tunnel_types — which types of tunnels this table accepts, the vibe check of tunnels 🌈

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💖 DESCRIPTION 💖

so the way this works: drivers are expected to provide either set_port and unset_port callbacks or the sync_table callback. like, pick a lane bestie. and heads up — callbacks are invoked with the rtnl lock held 🔒

now, 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. and the rule is: there must never be more than UDP_TUNNEL_NIC_MAX_SHARING_DEVICES devices sharing a table. that's the limit, periodt 💀

⚠️ 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, while not being a tunneled skb, and tunnel skbs from other ports 😭 so drivers should only use these ports for non-critical RX-side offloads, e.g. the checksum offload. non-critical only, bestie, don't get cute with it 🙏
• none of the devices care about the socket family at present, so we don't track it. please extend this code if you care 🫶 (like, if that's your thing, go off 👑)

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🦋 SEE ALSO 🦋

Kernel file ./include/net/udp_tunnel.h and udp_tunnel_nic_reset_ntf(9) — go read those next, they ate 💅✨

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and that's a wrap, bestie 🎀 this page lives in ./include/net, dated October 2026, and it's struct udp_tunnel_nic_info(9) in all its main character glory — go off, you understood the assignment 💖🌸🦋