[PATCH v3 05/15] cpu/hotplug: convert thread iterator to for_each_thread_rculock

[Ye Liu]

From: Ye Liu <liuye at kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_thread() loop in kernel/cpu.c with for_each_thread_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye at kylinos.cn>
Acked-by: Michal Hocko <mhocko at suse.com>
Reviewed-by: SJ Park <sj at kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs at kernel.org>
Reviewed-by: Oleg Nesterov <oleg at redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/cpu.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b3c8553d7bd6..00638d2abc0f 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1254,8 +1254,7 @@ void clear_tasks_mm_cpumask(int cpu)
 	 * full-fledged tasklist_lock.
 	 */
 	WARN_ON(cpu_online(cpu));
-	rcu_read_lock();
-	for_each_process(p) {
+	for_each_process_rculock(p) {
 		struct task_struct *t;
 
 		/*
@@ -1268,7 +1267,6 @@ void clear_tasks_mm_cpumask(int cpu)
 		arch_clear_mm_cpumask_cpu(cpu, t->mm);
 		task_unlock(t);
 	}
-	rcu_read_unlock();
 }
 
 /* Take this CPU down. */
-- 
2.25.1