From: Frederic Weisbecker frederic@kernel.org
[ 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@gmail.com Suggested-by: Paul E. McKenney paulmck@kernel.org Suggested-by: Neeraj Upadhyay quic_neeraju@quicinc.com Cc: Lai Jiangshan jiangshanlai@gmail.com Signed-off-by: Frederic Weisbecker frederic@kernel.org Signed-off-by: Paul E. McKenney paulmck@kernel.org Stable-dep-of: 28319d6dc5e2 ("rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()") Signed-off-by: Sasha Levin sashal@kernel.org --- 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); }