2023-12-12 17:43:49

by Neeraj upadhyay

Subject: [PATCH rcu 0/1] RCU tasks updates for v6.8

Hello,

This series contains RCU tasks updates:

1. rcu-tasks: Mark RCU Tasks accesses to current->rcu_tasks_idle_cpu.


Thanks
Neeraj

------------------------------------------------------------------------

tasks.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

2023-12-12 17:44:33

by Neeraj upadhyay

Subject: [PATCH rcu 1/1] rcu-tasks: Mark RCU Tasks accesses to current->rcu_tasks_idle_cpu

From: "Paul E. McKenney" <[email protected]>

The task_struct structure's ->rcu_tasks_idle_cpu can be concurrently
read and written from the RCU Tasks grace-period kthread and from the
CPU on which the task_struct structure's task is running. This commit
therefore marks the accesses appropriately.

Reported-by: Boqun Feng <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Joel Fernandes (Google) <[email protected]>
Signed-off-by: Neeraj Upadhyay (AMD) <[email protected]>
---
kernel/rcu/tasks.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index f54d5782eca0..732ad5b39946 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -975,7 +975,7 @@ static void check_holdout_task(struct task_struct *t,
t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) ||
!rcu_tasks_is_holdout(t) ||
(IS_ENABLED(CONFIG_NO_HZ_FULL) &&
- !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
+ !is_idle_task(t) && READ_ONCE(t->rcu_tasks_idle_cpu) >= 0)) {
WRITE_ONCE(t->rcu_tasks_holdout, false);
list_del_init(&t->rcu_tasks_holdout_list);
put_task_struct(t);
@@ -993,7 +993,7 @@ static void check_holdout_task(struct task_struct *t,
t, ".I"[is_idle_task(t)],
"N."[cpu < 0 || !tick_nohz_full_cpu(cpu)],
t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout,
- t->rcu_tasks_idle_cpu, cpu);
+ data_race(t->rcu_tasks_idle_cpu), cpu);
sched_show_task(t);
}

--
2.40.1