From 24f259ce3a7c8951f80c874c6193a8f8de139c22 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 25 Nov 2022 14:54:59 +0100 Subject: [PATCH] rcu-tasks: Remove preemption disablement around srcu_read_[un]lock() calls [ 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 Suggested-by: Paul E. McKenney Suggested-by: Neeraj Upadhyay Cc: Lai Jiangshan Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney Stable-dep-of: 28319d6dc5e2 ("rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()") Signed-off-by: Sasha Levin --- kernel/rcu/tasks.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 688c461036f5..80e75e7926cc 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); }