From: Frederic Weisbecker <frederic@xxxxxxxxxx>
[ Upstream commit 44757092958bdd749775022f915b7ac974384c2a ]
Ever since the following commit:
5a41344a3d83 ("srcu: Simplify __srcu_read_unlock() via this_cpu_dec()")
SRCU doesn't rely anymore on preemption to be disabled in order to
modify the per-CPU counter. And even then it used to be done from the API
itself.
Therefore and after checking further, it appears to be safe to remove
the preemption disablement around __srcu_read_[un]lock() in
exit_tasks_rcu_start() and exit_tasks_rcu_finish()
Suggested-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Suggested-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Suggested-by: Neeraj Upadhyay <quic_neeraju@xxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Stable-dep-of: 28319d6dc5e2 ("rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/rcu/tasks.h | 4 ----
1 file changed, 4 deletions(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 372644126b0de..c4af3c05663f4 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -596,9 +596,7 @@ static void show_rcu_tasks_classic_gp_kthread(void)
*/
void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu)
{
- preempt_disable();
current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
- preempt_enable();
}
/*
@@ -610,9 +608,7 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
{
struct task_struct *t = current;
- preempt_disable();
__srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx);
- preempt_enable();
exit_tasks_rcu_finish_trace(t);
}
--
2.39.2
