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Message-Id: <20221125135500.1653800-3-frederic@kernel.org>
Date: Fri, 25 Nov 2022 14:54:59 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: "Paul E . McKenney" <paulmck@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Frederic Weisbecker <frederic@...nel.org>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Oleg Nesterov <oleg@...hat.com>,
Pengfei Xu <pengfei.xu@...el.com>,
Boqun Feng <boqun.feng@...il.com>,
Lai Jiangshan <jiangshanlai@...il.com>, rcu@...r.kernel.org
Subject: [PATCH 2/3] rcu-tasks: Remove preemption disablement around srcu_read_[un]lock() calls
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@...il.com>
Suggested-by: Paul E. McKenney <paulmck@...nel.org>
Suggested-by: Neeraj Upadhyay <quic_neeraju@...cinc.com>
Cc: Lai Jiangshan <jiangshanlai@...il.com>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
---
kernel/rcu/tasks.h | 4 ----
1 file changed, 4 deletions(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 7deed6135f73..9a8114114b48 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1008,9 +1008,7 @@ EXPORT_SYMBOL_GPL(show_rcu_tasks_classic_gp_kthread);
*/
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();
}
/*
@@ -1022,9 +1020,7 @@ 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);
}
--
2.25.1
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