[PATCH 6/9] sched: Simplify sched_exec()

From: Peter Zijlstra
Date: Tue Aug 01 2023 - 17:25:09 EST


Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5431,23 +5431,20 @@ 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