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

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Date:   Mon, 14 Aug 2023 15:08:03 -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_core_cpu_{starting,deactivate}()

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

Commit-ID:     7170509cadbb76e5fa7d7b090d2cbdb93d56a2de
Gitweb:        https://git.kernel.org/tip/7170509cadbb76e5fa7d7b090d2cbdb93d56a2de
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Tue, 01 Aug 2023 22:41:30 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 14 Aug 2023 17:01:27 +02:00

sched: Simplify sched_core_cpu_{starting,deactivate}()

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/20230801211812.371787909@infradead.org
---
 kernel/sched/core.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f113a44..efe3848 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6400,20 +6400,24 @@ static void queue_core_balance(struct rq *rq)
 	queue_balance_callback(rq, &per_cpu(core_balance_head, rq->cpu), sched_core_balance);
 }
 
+DEFINE_LOCK_GUARD_1(core_lock, int,
+		    sched_core_lock(*_T->lock, &_T->flags),
+		    sched_core_unlock(*_T->lock, &_T->flags),
+		    unsigned long flags)
+
 static void sched_core_cpu_starting(unsigned int cpu)
 {
 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
 	struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
-	unsigned long flags;
 	int t;
 
-	sched_core_lock(cpu, &flags);
+	guard(core_lock)(&cpu);
 
 	WARN_ON_ONCE(rq->core != rq);
 
 	/* if we're the first, we'll be our own leader */
 	if (cpumask_weight(smt_mask) == 1)
-		goto unlock;
+		return;
 
 	/* find the leader */
 	for_each_cpu(t, smt_mask) {
@@ -6427,7 +6431,7 @@ static void sched_core_cpu_starting(unsigned int cpu)
 	}
 
 	if (WARN_ON_ONCE(!core_rq)) /* whoopsie */
-		goto unlock;
+		return;
 
 	/* install and validate core_rq */
 	for_each_cpu(t, smt_mask) {
@@ -6438,29 +6442,25 @@ static void sched_core_cpu_starting(unsigned int cpu)
 
 		WARN_ON_ONCE(rq->core != core_rq);
 	}
-
-unlock:
-	sched_core_unlock(cpu, &flags);
 }
 
 static void sched_core_cpu_deactivate(unsigned int cpu)
 {
 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
 	struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
-	unsigned long flags;
 	int t;
 
-	sched_core_lock(cpu, &flags);
+	guard(core_lock)(&cpu);
 
 	/* if we're the last man standing, nothing to do */
 	if (cpumask_weight(smt_mask) == 1) {
 		WARN_ON_ONCE(rq->core != rq);
-		goto unlock;
+		return;
 	}
 
 	/* if we're not the leader, nothing to do */
 	if (rq->core != rq)
-		goto unlock;
+		return;
 
 	/* find a new leader */
 	for_each_cpu(t, smt_mask) {
@@ -6471,7 +6471,7 @@ static void sched_core_cpu_deactivate(unsigned int cpu)
 	}
 
 	if (WARN_ON_ONCE(!core_rq)) /* impossible */
-		goto unlock;
+		return;
 
 	/* copy the shared state to the new leader */
 	core_rq->core_task_seq             = rq->core_task_seq;
@@ -6493,9 +6493,6 @@ static void sched_core_cpu_deactivate(unsigned int cpu)
 		rq = cpu_rq(t);
 		rq->core = core_rq;
 	}
-
-unlock:
-	sched_core_unlock(cpu, &flags);
 }
 
 static inline void sched_core_cpu_dying(unsigned int cpu)