STRUCT RCU_TASKS_PERCPU(9)

💅 NAME 💅

struct rcu_tasks_percpu — okay so this is the per-CPU piece of a Tasks-RCU-like mechanism's definition, and yes that's a mouthful but we're gonna get through it together bestie 🫶

So like, in the Kernel API Manual (that's the manual this page lives in, hiii ✨), this struct is literally the per-CPU component of a Tasks-RCU-style thing. One of these per CPU, no cap.

✨ SYNOPSIS ✨

struct rcu_tasks_percpu {
    struct rcu_segcblist cblist;
    raw_spinlock_t lock;
    unsigned long rtp_jiffies;
    unsigned long rtp_n_lock_retries;
    struct timer_list lazy_timer;
    unsigned int urgent_gp;
    struct work_struct rtp_work;
    struct irq_work rtp_irq_work;
    struct rcu_head barrier_q_head;
    struct list_head rtp_blkd_tasks;
    struct list_head rtp_exit_list;
    int cpu;
    int index;
    struct rcu_tasks *rtpp;
 };

Like, look at her. Fourteen members, all iconic, all doing their own little job 👑

🎀 Members 🎀

Here's the vibe check on every single field, in order, because we do not skip:

• cblist — the callback list. That's it, that's the girl. 💖
• lock — a raw_spinlock_t that protects the per-CPU callback list. Guard her at all costs 🔒
• rtp_jiffies — jiffies counter value, but specifically for statistics. Numbers for the vibes 📊
• rtp_n_lock_retries — a rough lock-contention statistic. Rough! It said rough, don't @ me 😭
• lazy_timer — a timer whose whole personality is unlazifying callbacks. Get up bestie ⏰
• urgent_gp — number of additional non-lazy grace periods. Urgent! 🚨
• rtp_work — work queue for invoking callbacks. She's got a queue and she's working it 💅
• rtp_irq_work — IRQ work queue, for deferred wakeups. Waking up later, on purpose 🌙
• barrier_q_head — an struct rcu_head that serves as the RCU callback for a barrier operation. Barrier queen 🧱
• rtp_blkd_tasks — list of tasks blocked as readers. Free them 😤
• rtp_exit_list — list of tasks in the latter portion of do_exit. They're leaving, let them leave 🚪
• cpu — the CPU number corresponding to this entry. Which CPU? This CPU. 🖥️
• index — index of this CPU in rtpcp_array of the rcu_tasks structure. Your seat number in the group chat 🪑
• rtpp — pointer to the rcu_tasks structure. Her parent, her home base 🏠

ngl if you're touching lock you better actually be holding it — it's the lock protecting the per-CPU callback list, so like, do the thing properly fr fr 🙈

🌈 SEE ALSO 🌈

Kernel file ./kernel/rcu/tasks.h plus these besties, go read them too:

• struct rcu_tasks(9)
• call_rcu_tasks(9)
• synchronize_rcu_tasks(9)
• rcu_barrier_tasks(9)
• synchronize_rcu_tasks_rude(9)

okay that's the whole page, you ate that 🍓 This little number ships from the source ./kernel/rcu, dated October 2026, and it's filed under struct rcu_tasks_percpu(9) — mwah, periodt 💜