[tip: sched/core] sched: Simplify set_user_nice()

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     7db0c4c81425e6e0d69dcb56e8c5e99d63f4ef07
Gitweb:        https://git.kernel.org/tip/7db0c4c81425e6e0d69dcb56e8c5e99d63f4ef07
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Fri, 09 Jun 2023 20:52:55 +02:00
Committer:     root <root@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
CommitterDate: Sat, 09 Sep 2023 15:10:14 +02:00

sched: Simplify set_user_nice()

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 kernel/sched/core.c  | 13 ++++++-------
 kernel/sched/sched.h |  5 +++++
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index efe3848..e4d8b7a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7188,9 +7188,8 @@ static inline int rt_effective_prio(struct task_struct *p, int prio)
 void set_user_nice(struct task_struct *p, long nice)
 {
 	bool queued, running;
-	int old_prio;
-	struct rq_flags rf;
 	struct rq *rq;
+	int old_prio;
 
 	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
 		return;
@@ -7198,7 +7197,9 @@ void set_user_nice(struct task_struct *p, long nice)
 	 * We have to be careful, if called from sys_setpriority(),
 	 * the task might be in the middle of scheduling on another CPU.
 	 */
-	rq = task_rq_lock(p, &rf);
+	CLASS(task_rq_lock, rq_guard)(p);
+	rq = rq_guard.rq;
+
 	update_rq_clock(rq);
 
 	/*
@@ -7209,8 +7210,9 @@ void set_user_nice(struct task_struct *p, long nice)
 	 */
 	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
 		p->static_prio = NICE_TO_PRIO(nice);
-		goto out_unlock;
+		return;
 	}
+
 	queued = task_on_rq_queued(p);
 	running = task_current(rq, p);
 	if (queued)
@@ -7233,9 +7235,6 @@ void set_user_nice(struct task_struct *p, long nice)
 	 * lowered its priority, then reschedule its CPU:
 	 */
 	p->sched_class->prio_changed(rq, p, old_prio);
-
-out_unlock:
-	task_rq_unlock(rq, p, &rf);
 }
 EXPORT_SYMBOL(set_user_nice);
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 3a01b7a..62013c4 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1657,6 +1657,11 @@ task_rq_unlock(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
 	raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
 }
 
+DEFINE_LOCK_GUARD_1(task_rq_lock, struct task_struct,
+		    _T->rq = task_rq_lock(_T->lock, &_T->rf),
+		    task_rq_unlock(_T->rq, _T->lock, &_T->rf),
+		    struct rq *rq; struct rq_flags rf)
+
 static inline void
 rq_lock_irqsave(struct rq *rq, struct rq_flags *rf)
 	__acquires(rq->lock)