linux-kernel - [tip: sched/core] sched: Simplify sched

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Date:   Mon, 14 Aug 2023 15:08:04 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Valentin Schneider <vschneid@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched: Simplify sched_exec()

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

Commit-ID:     4bdada79f3464d85f6e187213c088e7c934e0554
Gitweb:        https://git.kernel.org/tip/4bdada79f3464d85f6e187213c088e7c934e0554
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Tue, 01 Aug 2023 22:41:27 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 14 Aug 2023 17:01:26 +02:00

sched: Simplify sched_exec()

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Valentin Schneider <vschneid@...hat.com>
Link: https://lore.kernel.org/r/20230801211812.168490417@infradead.org
---
 kernel/sched/core.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 68bd68d..cd7f2ed 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5498,23 +5498,20 @@ unsigned int nr_iowait(void)
 void sched_exec(void)
 {
 	struct task_struct *p = current;
-	unsigned long flags;
+	struct migration_arg arg;
 	int dest_cpu;
 
-	raw_spin_lock_irqsave(&p->pi_lock, flags);
-	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), WF_EXEC);
-	if (dest_cpu == smp_processor_id())
-		goto unlock;
+	scoped_guard (raw_spinlock_irqsave, &p->pi_lock) {
+		dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), WF_EXEC);
+		if (dest_cpu == smp_processor_id())
+			return;
 
-	if (likely(cpu_active(dest_cpu))) {
-		struct migration_arg arg = { p, dest_cpu };
+		if (unlikely(!cpu_active(dest_cpu)))
+			return;
 
-		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
-		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
-		return;
+		arg = (struct migration_arg){ p, dest_cpu };
 	}
-unlock:
-	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+	stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
 }
 
 #endif