rcu_watchin...topped_since(9)

💖 NAME 💖

Okay so this is the Kernel API Manual page for rcu_watching_snap_stopped_since, and it answers the very specific question: has RCU stopped watching a given CPU since the specified @snap? Bestie, it's giving deeply niche RCU main-character energy and I am obsessed. 🦋✨

🌸 SYNOPSIS 🌸

bool rcu_watching_snap_stopped_since (struct rcu_data *rdp , int snap );

🎀 ARGUMENTS 🎀

• rdp — the rcu_data corresponding to the CPU for which to check EQS.
• snap — the rcu_watching snapshot taken when the CPU wasn't in an EQS.

✨ DESCRIPTION ✨

Returns true if the CPU corresponding to rdp has spent some time in an extended quiescent state since snap. Note that this doesn't check if it /still/ is in an EQS — it only checks that it went through one since snap. Lowkey a different question, okay? 👀

This is meant to be used in a loop waiting for a CPU to go through an EQS. So like, it's the "are we there yet?" of RCU checks, fr fr. 🔥

🌈 SEE ALSO 🌈

Kernel file ./kernel/rcu/tree.c, plus the whole SEE ALSO bestie lineup:

• rcu_softirq_qs(9)
• rcu_is_cpu_rrupt_from_idle(9)
• rcu_irq_exit_check_preempt(9)
• __rcu_irq_enter_check_tick(9)
• rcu_is_watching(9)
• rcu_set_gpwrap_lag(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)

Cute little sign-off: this page is from source/version ./kernel/rcu, dated October 2026, and the header energy is rcu_watchin...topped_since(9). Slay, kernel docs, slay. 💅🎀💖