From: Paul E. McKenney <paulmck@kernel.org>
Date: Sat, 4 Mar 2023 21:40:55 +0000 (-0800)
Subject: rcu: Add comment to rcu_do_batch() identifying rcuoc code path
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=09853fb89f6bc46727ccd325c0f6f266df51d155;p=linux.git

rcu: Add comment to rcu_do_batch() identifying rcuoc code path

This commit adds a comment to help explain why the "else" clause of the
in_serving_softirq() "if" statement does not need to enforce a time limit.
The reason is that this "else" clause handles rcuoc kthreads that do not
block handlers for other softirq vectors.

Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8e880c09ab59e..06cc6a6ad8199 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2131,6 +2131,8 @@ static void rcu_do_batch(struct rcu_data *rdp)
 				break;
 			}
 		} else {
+			// In rcuoc context, so no worries about depriving
+			// other softirq vectors of CPU cycles.
 			local_bh_enable();
 			lockdep_assert_irqs_enabled();
 			cond_resched_tasks_rcu_qs();