[PATCH 1/6] sched/deadline: Consolidate the SCHED_DL task_can_attach() check on its own function

[Daniel Bristot de Oliveira <bristot@redhat.com>]

It is easier to track the restrictions imposed on SCHED_DEADLINE
tasks if we keep them all together in a single function.

No function changes.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel@vger.kernel.org
Cc: cgroups@vger.kernel.org
---
 kernel/sched/core.c     | 3 +--
 kernel/sched/deadline.c | 7 +++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7af80c3fce12..f4aede34449c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7142,8 +7142,7 @@ int task_can_attach(struct task_struct *p,
 		goto out;
 	}
 
-	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
-					      cs_cpus_allowed))
+	if (dl_task(p))
 		ret = dl_task_can_attach(p, cs_cpus_allowed);
 
 out:
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 75686c6d4436..c97d2c707b98 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2870,6 +2870,13 @@ int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allo
 	bool overflow;
 	int ret;
 
+	/*
+	 * The task is not moving to another root domain, so it is
+	 * already accounted.
+	 */
+	if (cpumask_intersects(task_rq(p)->rd->span, cs_cpus_allowed))
+		return 0;
+
 	dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
 
 	rcu_read_lock_sched();
-- 
2.29.2