[PATCH v2 6/8] fs: convert process/thread iterators to for_each_*_rculock

[Ye Liu <ye.liu@linux.dev>]

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pairs combined
with for_each_process() and for_each_process_thread() loops in fs/
with the for_each_*_rculock() macros, which scope the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
---
Changes in v2:
  - Rename *_rcu to *_rculock
 fs/proc/base.c        | 4 +---
 fs/resctrl/rdtgroup.c | 8 ++------
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6a39de424f62..3de4f4557e4c 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1160,8 +1160,7 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
 	if (mm) {
 		struct task_struct *p;
 
-		rcu_read_lock();
-		for_each_process(p) {
+		for_each_process_rculock(p) {
 			if (same_thread_group(task, p))
 				continue;
 
@@ -1177,7 +1176,6 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
 			}
 			task_unlock(p);
 		}
-		rcu_read_unlock();
 		mmdrop(mm);
 	}
 err_unlock:
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5dcbb0a964e8..b14df8b23f1a 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -709,14 +709,12 @@ int rdtgroup_tasks_assigned(struct rdtgroup *r)
 
 	lockdep_assert_held(&rdtgroup_mutex);
 
-	rcu_read_lock();
-	for_each_process_thread(p, t) {
+	for_each_process_thread_rculock(p, t) {
 		if (is_closid_match(t, r) || is_rmid_match(t, r)) {
 			ret = 1;
 			break;
 		}
 	}
-	rcu_read_unlock();
 
 	return ret;
 }
@@ -826,15 +824,13 @@ static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
 	struct task_struct *p, *t;
 	pid_t pid;
 
-	rcu_read_lock();
-	for_each_process_thread(p, t) {
+	for_each_process_thread_rculock(p, t) {
 		if (is_closid_match(t, r) || is_rmid_match(t, r)) {
 			pid = task_pid_vnr(t);
 			if (pid)
 				seq_printf(s, "%d\n", pid);
 		}
 	}
-	rcu_read_unlock();
 }
 
 static int rdtgroup_tasks_show(struct kernfs_open_file *of,
-- 
2.25.1