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 8e880c0..06cc6a6 100644 (file)
--- 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();