[PATCH v2 19/21] srcutree: Add lockdep and early-boot checks to synchronize_srcu_atomic()

[Paul E. McKenney]

From: Kunwu Chan <kunwu.chan@xxxxxxxxx>

Add the lockdep annotation, same-type SRCU nesting warning, and
early-boot check used by __synchronize_srcu().

Suggested-by: Zqiang <qiang.zhang@xxxxxxxxx>
Signed-off-by: Kunwu Chan <kunwu.chan@xxxxxxxxx>
Reviewed-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/srcutree.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 6e37d53b412e1..7890f7c7c2ee7 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -2122,6 +2122,14 @@ void synchronize_srcu_atomic(struct srcu_struct *ssp)
 	unsigned long rdm0, rdm1;
 	unsigned long unlocks0, unlocks1;
 
+	srcu_lock_sync(&ssp->dep_map);
+
+	RCU_LOCKDEP_WARN(lockdep_is_held(ssp),
+			 "Illegal synchronize_srcu_atomic() in same-type SRCU read-side critical section");
+
+	if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
+		return;
+
 	// Initialize.	Either init_srcu_struct() was invoked or
 	// DEFINE_SRCU() or similar was used.  Therefore, no allocation
 	// will be done here.
-- 
2.40.1