rcu_set_gpwrap_lag(9)

✨ rcu_set_gpwrap_lag ✨

Okay bestie, welcome to the kernel API manual for rcu_set_gpwrap_lag(9) — yes, that’s the whole vibe, and no, we are not skipping a single detail. 🫶

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🌸 NAME 🌸

rcu_set_gpwrap_lag — set the RCU GP sequence overflow lag value. Lowkey iconic, highkey niche. 💅

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🦋 SYNOPSIS 🦋

void rcu_set_gpwrap_lag (unsigned long lag_gps );

That’s it. That’s the whole signature. Slay. ✨

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🎀 ARGUMENTS 🎀

• lag_gps — set the overflow lag to this many grace period worth of counters. It’s used by rcutorture to quickly force a gpwrap situation. And if lag_gps = 0, that means we reset it back to the boot-time value. Periodt. 💖

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👑 SEE ALSO 👑

Kernel file ./kernel/rcu/tree.c — and literally all of these friends:

• rcu_softirq_qs(9)
• rcu_watching_snap_stopped_since(9)
• rcu_is_cpu_rrupt_from_idle(9)
• rcu_irq_exit_check_preempt(9)
• __rcu_irq_enter_check_tick(9)
• rcu_is_watching(9)
• call_rcu_hurry(9)
• call_rcu(9)
• synchronize_rcu(9)
• get_completed_synchronize_rcu_full(9)
• get_state_synchronize_rcu(9)
• get_state_synchronize_rcu_full(9)
• start_poll_synchronize_rcu(9)
• start_poll_synchronize_rcu_full(9)
• poll_state_synchronize_rcu(9)
• poll_state_synchronize_rcu_full(9)
• cond_synchronize_rcu(9)
• cond_synchronize_rcu_full(9)
• rcu_barrier(9)
• rcu_barrier_throttled(9)

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💀 Friendly reminder: lag_gps = 0 is not a “nothing” value, bestie — it resets the overflow lag back to the boot-time value. Do not play with it unless you know what you’re doing.

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And that’s the page, bestie! This little piece of kernel lore lives in ./kernel/rcu, dates back to October 2026, and the manual page is literally called rcu_set_gpwrap_lag(9). Go forth and force a gpwrap situation responsibly. 🌈💜