call_rcu_tasks(9)

🌸 NAME 🌸

call_rcu_tasks(9) — from the Kernel API Manual, bestie — Queue an RCU for invocation task-based grace period. 💅

✨ SYNOPSIS ✨

void call_rcu_tasks (struct rcu_head *rhp , rcu_callback_t func );

🎀 ARGUMENTS 🎀

• rhp — structure to be used for queueing the RCU updates. 🫶
• func — actual callback function to be invoked after the grace period. 🌟

🦋 DESCRIPTION 🦋

okay so here's the tea: the callback function will be invoked some time after a full grace period elapses — in other words, after all currently executing rcu-tasks read-side critical sections have completed. ✨

call_rcu_tasks assumes that those read-side critical sections end at a voluntary context switch (not a preemption!), at cond_resched_tasks_rcu_qs, at entry into idle, or at transition to usermode execution. periodt. 💅

Because of that, there are no read-side primitives analogous to rcu_read_lock and rcu_read_unlock — none, zero, not a one 💀 — because this primitive is intended to determine that all tasks have passed through a safe state, not so much for data-structure synchronization. It's giving "safe-state detector," not "data-structure-sync main character." 🫶

See the description of call_rcu for more detailed information on memory ordering guarantees. iykyk 🔥

🌈 SEE ALSO 🌈

• Kernel file ./kernel/rcu/tasks.h — struct rcu_tasks_percpu(9), struct rcu_tasks(9), synchronize_rcu_tasks(9), rcu_barrier_tasks(9), synchronize_rcu_tasks_rude(9) 👑

mwah 💋 source/version: ./kernel/rcu · date: October 2026 · page: call_rcu_tasks(9) — bye bestie, go queue that callback responsibly! 🎀🦋