[PATCH rcu 07/10] rcu: Make rcu_blocking_is_gp() stop early-boot might_sleep()

[Paul E. McKenney]

From: Zqiang <qiang1.zhang@xxxxxxxxx>

Currently, rcu_blocking_is_gp() invokes might_sleep() even during early
boot when interrupts are disabled and before the scheduler is scheduling.
This is at best an accident waiting to happen.  Therefore, this commit
moves that might_sleep() under an rcu_scheduler_active check in order
to ensure that might_sleep() is not invoked unless sleeping might actually
happen.

Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/tree.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 0147e69ea85a9..15f9765064727 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3333,9 +3333,10 @@ void __init kfree_rcu_scheduler_running(void)
  */
 static int rcu_blocking_is_gp(void)
 {
-	if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE)
+	if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) {
+		might_sleep();
 		return false;
-	might_sleep();  /* Check for RCU read-side critical section. */
+	}
 	return true;
 }
 
-- 
2.31.1.189.g2e36527f23