From: Ankur Arora <ankur.a.ar...@oracle.com>
Update comment in __cond_resched() clarifying how urgently needed
quiescent state are provided.
Signed-off-by: Ankur Arora <ankur.a.ar...@oracle.com>
Reviewed-by: Frederic Weisbecker <frede...@kernel.org>
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
Signed-off-by: Boqun Feng <boqun.f...@gmail.com>
---
kernel/sched/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 165c90ba64ea..d328707626e3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7289,7 +7289,7 @@ int __sched __cond_resched(void)
return 1;
}
/*
- * In preemptible kernels, ->rcu_read_lock_nesting tells the tick
+ * In PREEMPT_RCU kernels, ->rcu_read_lock_nesting tells the tick
* whether the current CPU is in an RCU read-side critical section,
* so the tick can report quiescent states even for CPUs looping
* in kernel context. In contrast, in non-preemptible kernels,
@@ -7298,6 +7298,8 @@ int __sched __cond_resched(void)
* RCU quiescent state. Therefore, the following code causes
* cond_resched() to report a quiescent state, but only when RCU
* is in urgent need of one.
+ * A third case, preemptible, but non-PREEMPT_RCU provides for
+ * urgently needed quiescent states via rcu_flavor_sched_clock_irq().
*/
#ifndef CONFIG_PREEMPT_RCU
rcu_all_qs();
--
2.39.5 (Apple Git-154)
