UNION TMIGR_STATE(9)

💜 union tmigr_state(9) — a Kernel API Manual moment

okay so bestie, welcome to the Kernel API Manual and today's main character is union tmigr_state(9) — literally the state of tmigr_group, no cap ✨

🌸 NAME 🌸

union tmigr_state — the state of tmigr_group 🫶

✨ SYNOPSIS ✨

like, here's the whole vibe, exactly as it lives:

union tmigr_state {
    u32 state;
    struct {
      u8 active;
      u8 migrator;
      u16 seq;
    };
 };

🎀 Members 🎀

• state — the combined version of the state — and heads up, it's only used for the atomic read/cmpxchg function 💅 then there's the anon struct: that's the split version of the state, and you only use the struct members to update information so you stay independent of endianness 👑
• {unnamed_struct} — anonymous, mysterious, iconic, no name needed 🧚
• active — contains each mask bit of the active children 🌈
• migrator — contains the mask of the child which is migrator 👑
• seq — the sequence counter, and it needs to be increased whenever an update to the tmigr_state is done ⭐ because it prevents a race when updates in the child groups get propagated in a changed order 😭 the detailed info about that whole scenario is given in the documentation at the begin of timer_migration.c — go read it, iykyk 📖

🦋 SEE ALSO 🦋

Kernel file ./kernel/time/timer_migration.h plus the whole friend group: struct tmigr_hierarchy(9), struct tmigr_event(9), struct tmigr_group(9), and struct tmigr_cpu(9) 💖

fr fr that's the whole page — every member, every warning, every cross-reference accounted for 🙈

k bye bestie, this one's a wrap 💜 from ./kernel/time, dated October 2026 🎀 slay ✨