[PATCH v3 10/15] sched: convert process/thread iterators to for_each_*_rculock

[Ye Liu]

From: Ye Liu <liuye at kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() and guard(rcu)
pairs combined with for_each_process_thread() loops in kernel/sched/
with for_each_process_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/sched/core.c  | 3 +--
 kernel/sched/debug.c | 4 +---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0697ed0f1c3d..fd5bdd2cb798 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2005,8 +2005,7 @@ static void uclamp_sync_util_min_rt_default(void)
 	smp_mb__after_spinlock();
 	read_unlock(&tasklist_lock);
 
-	guard(rcu)();
-	for_each_process_thread(g, p)
+	for_each_process_thread_rculock(g, p)
 		uclamp_update_util_min_rt_default(p);
 }
 
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 72236db67983..cdae165b98f7 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1029,14 +1029,12 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
 #endif
 		   "\n");
 
-	rcu_read_lock();
-	for_each_process_thread(g, p) {
+	for_each_process_thread_rculock(g, p) {
 		if (task_cpu(p) != rq_cpu)
 			continue;
 
 		print_task(m, rq, p);
 	}
-	rcu_read_unlock();
 }
 
 void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
-- 
2.25.1