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

[Daniel Bristot de Oliveira]

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@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Valentin Schneider <valentin.schneider@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: cgroups@xxxxxxxxxxxxxxx
---
 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