STRUCT MR_MFC(9)

🦋 struct mr_mfc(9) — the kernel API manual, bestie edition 🦋

okay so this is a page from the Kernel API Manual, and it's all about struct mr_mfc — literally the common multicast routing entries. no cap, that's the whole vibe. it's a kernel struct page, so it's giving "here's the shape, here's the fields, go read the source" 💅

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✨ NAME ✨

struct mr_mfc — common multicast routing entries 🎀

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🌸 SYNOPSIS 🌸

here's the whole struct, character for character, because we do not mess with source code in this house:

struct mr_mfc {
    struct rhlist_head mnode;
    unsigned short mfc_parent;
    int mfc_flags;
    union {
      struct {
        unsigned long expires;
        struct sk_buff_head unresolved;
      } unres;
      struct {
        unsigned long last_assert;
        int minvif;
        int maxvif;
        atomic_long_t bytes;
        atomic_long_t pkt;
        atomic_long_t wrong_if;
        unsigned long lastuse;
        unsigned char ttls[MAXVIFS];
        refcount_t refcount;
      } res;
    } mfc_un;
    struct list_head list;
    struct rcu_head rcu;
    void (*free)(struct rcu_head *head);
 };

like, look at that union. mfc_un said "why have one struct when you can have two, bestie" 😭🫶

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👑 Members 👑

• mnode — rhashtable list ✨
• mfc_parent — source interface (iif) 💖
• mfc_flags — entry flags 🎀
• list — global entry list 🌸
• rcu — used for entry destruction 💀
• free — Operation used for freeing an entry under RCU 🔥

ngl the free one is main character energy — you're handing over the operation that frees an entry while it's still under RCU, so pay attention, okay? 🙈

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🌈 SEE ALSO 🌈

• Kernel file ./include/linux/mroute_base.h
• struct vif_device(9)
• struct mr_table_ops(9)
• struct mr_table(9)

go read the whole little mroute_base.h family, they're all iconic together 💜

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and that's the page, bestie! this one came from ./include/linux, dated October 2026, and the footer says struct mr_mfc(9) — so you know exactly where to cite it. slay 💅✨🦋