[PATCH 18/22] sched/core: remove unneeded cpumask_weight() in sched_core_cpu_{starting,deactivate}

[Yury Norov]

The following cpumask_any_but() implicitly calculates if number of smt cpus
is equal to 1, therefore we can drop the code that does it explicitly.

CC: Ben Segall <bsegall@xxxxxxxxxx>
CC: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
CC: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Juri Lelli <juri.lelli@xxxxxxxxxx>
CC: Mel Gorman <mgorman@xxxxxxx>
CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
CC: Valentin Schneider <vschneid@xxxxxxxxxx>
CC: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
CC: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
---
This is RFC because it drops WARN_ON_ONCE(rq->core != rq). If this warinig
is important, I'll rework the patch.

 kernel/sched/core.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9700001948d0..07b8f35cbe36 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6133,12 +6133,10 @@ static void sched_core_cpu_starting(unsigned int 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;
-
 	/* find the leader */
 	t = cpumask_any_but(smt_mask, cpu);
+
+	/* if we're the first, we'll be our own leader */
 	if (t >= nr_cpu_ids)
 		goto unlock;
 
@@ -6171,18 +6169,14 @@ static void sched_core_cpu_deactivate(unsigned int cpu)
 
 	sched_core_lock(cpu, &flags);
 
-	/* if we're the last man standing, nothing to do */
-	if (cpumask_weight(smt_mask) == 1) {
-		WARN_ON_ONCE(rq->core != rq);
-		goto unlock;
-	}
-
 	/* if we're not the leader, nothing to do */
 	if (rq->core != rq)
 		goto unlock;
 
 	/* find a new leader */
 	t = cpumask_any_but(smt_mask, cpu);
+
+	/* if we're the last man standing, nothing to do */
 	if (t >= nr_cpu_ids)
 		goto unlock;
 
-- 
2.32.0