same_state_synchronize_rcu(9)

💅 NAME 💅

welcome to the Kernel API Manual, bestie — today’s main character is same_state_synchronize_rcu (yes, the (9) is part of the whole vibe ✨), and the question on the table is: are two old-state values identical? 👀

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🎀 SYNOPSIS 🎀

the whole mood, exactly as written:

bool same_state_synchronize_rcu (unsigned long oldstate1 , unsigned long
       oldstate2 );

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🦋 ARGUMENTS 🦋

• oldstate1 — the first old-state value, bestie 🫶
• oldstate2 — the second old-state value, no cap 💅

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✨ DESCRIPTION ✨

okay so here’s the tea, and it’s actually simple: both old-state values must have been obtained from either get_state_synchronize_rcu, start_poll_synchronize_rcu, or get_completed_synchronize_rcu. that’s the rule — not me making stuff up, it’s literally the requirement 💖

then the function returns true if the two values are identical and false otherwise. cute, right? it’s giving tiny bool energy.

this lets structures whose lifetimes are tracked by old-state values push these values to a list header, and that allows those structures to be slightly smaller. slay for memory efficiency, honestly 🌸

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🌈 SEE ALSO 🌈

go read these too, bestie — all of them, in this exact order, because the lore is real:

• Kernel file ./include/linux/rcupdate.h
• cond_resched_tasks_rcu_qs(9)
• rcu_softirq_qs_periodic(9)
• RCU_LOCKDEP_WARN(9)
• lockdep_assert_in_rcu_read_lock(9)
• lockdep_assert_in_rcu_read_lock_bh(9)
• lockdep_assert_in_rcu_read_lock_sched(9)
• lockdep_assert_in_rcu_reader(9)
• unrcu_pointer(9)
• RCU_INITIALIZER(9)
• rcu_assign_pointer(9)
• rcu_replace_pointer(9)
• rcu_access_pointer(9)
• rcu_dereference_check(9)
• rcu_dereference_bh_check(9)
• rcu_dereference_sched_check(9)
• rcu_dereference_all_check(9)
• rcu_dereference_protected(9)
• rcu_dereference(9)
• rcu_dereference_bh(9)
• rcu_dereference_sched(9)
• rcu_dereference_all(9)
• rcu_pointer_handoff(9)
• rcu_read_lock(9)
• rcu_read_unlock(9)
• rcu_read_lock_bh(9)
• rcu_read_unlock_bh(9)
• rcu_read_lock_sched(9)
• rcu_read_unlock_sched(9)
• RCU_INIT_POINTER(9)
• RCU_POINTER_INITIALIZER(9)
• kfree_rcu(9)
• kfree_rcu_mightsleep(9)
• kfree_rcu_nolock(9)
• rcu_head_init(9)
• rcu_head_after_call_rcu(9)

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🎀 that’s the whole page, bestie — source/version ./include/linux, date October 2026, and the title stays same_state_synchronize_rcu(9) 🎀