From 622c508bcf4852ad56ae37bf6f08e9a4e6aa95b2 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@kernel.org>
Date: Tue, 27 May 2025 15:33:01 +0200
Subject: cpu: Provide lockdep check for CPU hotplug lock write-held

cpuset modifies partitions, including isolated, while holding the cpu
hotplug lock read-held.

This means that write-holding the CPU hotplug lock is safe to
synchronize against housekeeping cpumask changes.

Provide a lockdep check to validate that.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Marco Crivellari <marco.crivellari@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: linux-kernel@vger.kernel.org
---
 kernel/cpu.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'kernel')

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 40b8496f47c5..01968a5c4a16 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -534,6 +534,11 @@ int lockdep_is_cpus_held(void)
 {
 	return percpu_rwsem_is_held(&cpu_hotplug_lock);
 }
+
+int lockdep_is_cpus_write_held(void)
+{
+	return percpu_rwsem_is_write_held(&cpu_hotplug_lock);
+}
 #endif
 
 static void lockdep_acquire_cpus_lock(void)
-- 
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