sched: Simplify sched_tick_remote()

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230801211812.236247952@infradead.org

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cd7f2ed..1b2fa91 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5721,9 +5721,6 @@ static void sched_tick_remote(struct work_struct *work)
        struct tick_work *twork = container_of(dwork, struct tick_work, work);
        int cpu = twork->cpu;
        struct rq *rq = cpu_rq(cpu);
-       struct task_struct *curr;
-       struct rq_flags rf;
-       u64 delta;
        int os;
 
        /*
@@ -5733,30 +5730,26 @@ static void sched_tick_remote(struct work_struct *work)
         * statistics and checks timeslices in a time-independent way, regardless
         * of when exactly it is running.
         */
-       if (!tick_nohz_tick_stopped_cpu(cpu))
-               goto out_requeue;
+       if (tick_nohz_tick_stopped_cpu(cpu)) {
+               guard(rq_lock_irq)(rq);
+               struct task_struct *curr = rq->curr;
 
-       rq_lock_irq(rq, &rf);
-       curr = rq->curr;
-       if (cpu_is_offline(cpu))
-               goto out_unlock;
+               if (cpu_online(cpu)) {
+                       update_rq_clock(rq);
 
-       update_rq_clock(rq);
+                       if (!is_idle_task(curr)) {
+                               /*
+                                * Make sure the next tick runs within a
+                                * reasonable amount of time.
+                                */
+                               u64 delta = rq_clock_task(rq) - curr->se.exec_start;
+                               WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+                       }
+                       curr->sched_class->task_tick(rq, curr, 0);
 
-       if (!is_idle_task(curr)) {
-               /*
-                * Make sure the next tick runs within a reasonable
-                * amount of time.
-                */
-               delta = rq_clock_task(rq) - curr->se.exec_start;
-               WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+                       calc_load_nohz_remote(rq);
+               }
        }
-       curr->sched_class->task_tick(rq, curr, 0);
-
-       calc_load_nohz_remote(rq);
-out_unlock:
-       rq_unlock_irq(rq, &rf);
-out_requeue:
 
        /*
         * Run the remote tick once per second (1Hz). This arbitrary