[PATCH v4 2/5] rcu/tree: Clarify comments about FQS loop reporting quiescent states

[Joel Fernandes (Google)]

At least since v4.19, the FQS loop no longer reports quiescent states
for offline CPUs unless it is an emergency.

This commit therefore fixes the comment in rcu_gp_init() to match the
current code.

Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
 kernel/rcu/tree.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a49fa3b60faa..2fb66cdbfa25 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1701,9 +1701,11 @@ static bool rcu_gp_init(void)
 
 	/*
 	 * Apply per-leaf buffered online and offline operations to the
-	 * rcu_node tree.  Note that this new grace period need not wait
-	 * for subsequent online CPUs, and that quiescent-state forcing
-	 * will handle subsequent offline CPUs.
+	 * rcu_node tree. Note that this new grace period need not wait for
+	 * subsequent online CPUs, and that RCU hooks in the CPU offlining
+	 * path, when combined with checks in this function, will handle CPUs
+	 * that are currently going offline or that go offline later. Refer to
+	 * RCU's Requirements documentation about hotplug requirements as well.
 	 */
 	rcu_state.gp_state = RCU_GP_ONOFF;
 	rcu_for_each_leaf_node(rnp) {
-- 
2.28.0.236.gb10cc79966-goog