[tip: core/rcu] cpu/hotplug: Add lockdep_is_cpus_held()

[tip-bot2 for Frederic Weisbecker]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     43759fe5a137389e94ed6d4680c3c63c17273158
Gitweb:        https://git.kernel.org/tip/43759fe5a137389e94ed6d4680c3c63c17273158
Author:        Frederic Weisbecker <frederic@xxxxxxxxxx>
AuthorDate:    Wed, 11 Nov 2020 23:53:13 +01:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Wed, 06 Jan 2021 16:24:59 -08:00

cpu/hotplug: Add lockdep_is_cpus_held()

This commit adds a lockdep_is_cpus_held() function to verify that the
proper locks are held and that various operations are running in the
correct context.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 include/linux/cpu.h | 2 ++
 kernel/cpu.c        | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d6428aa..3aaa068 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -111,6 +111,8 @@ static inline void cpu_maps_update_done(void)
 #endif /* CONFIG_SMP */
 extern struct bus_type cpu_subsys;
 
+extern int lockdep_is_cpus_held(void);
+
 #ifdef CONFIG_HOTPLUG_CPU
 extern void cpus_write_lock(void);
 extern void cpus_write_unlock(void);
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 4e11e91..1b6302e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -330,6 +330,13 @@ void lockdep_assert_cpus_held(void)
 	percpu_rwsem_assert_held(&cpu_hotplug_lock);
 }
 
+#ifdef CONFIG_LOCKDEP
+int lockdep_is_cpus_held(void)
+{
+	return percpu_rwsem_is_held(&cpu_hotplug_lock);
+}
+#endif
+
 static void lockdep_acquire_cpus_lock(void)
 {
 	rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_);