[PATCH sched_ext/for-6.11] sched, sched_ext: Simplify dl_prio() case handling in sched_fork()

[Tejun Heo]

From: Tejun Heo <tj@xxxxxxxxxx>

sched_fork() returns with -EAGAIN if dl_prio(@p). a7a9fc549293 ("sched_ext:
Add boilerplate for extensible scheduler class") added scx_pre_fork() call
before it and then scx_cancel_fork() on the exit path. This is silly as the
dl_prio() block can just be moved above the scx_pre_fork() call.

Move the dl_prio() block above the scx_pre_fork() call and remove the now
unnecessary scx_cancel_fork() invocation.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: David Vernet <void@xxxxxxxxxxxxx>
---
Hello,

As this is pretty trivial, if no one objects, I'll apply this to
sched_ext/for-6.11 after a bit.

Thanks.

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

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4583,8 +4583,6 @@ late_initcall(sched_core_sysctl_init);
  */
 int sched_fork(unsigned long clone_flags, struct task_struct *p)
 {
-	int ret;
-
 	__sched_fork(clone_flags, p);
 	/*
 	 * We mark the process as NEW here. This guarantees that
@@ -4621,12 +4619,12 @@ int sched_fork(unsigned long clone_flags
 		p->sched_reset_on_fork = 0;
 	}
 
+	if (dl_prio(p->prio))
+		return -EAGAIN;
+
 	scx_pre_fork(p);
 
-	if (dl_prio(p->prio)) {
-		ret = -EAGAIN;
-		goto out_cancel;
-	} else if (rt_prio(p->prio)) {
+	if (rt_prio(p->prio)) {
 		p->sched_class = &rt_sched_class;
 #ifdef CONFIG_SCHED_CLASS_EXT
 	} else if (task_should_scx(p)) {
@@ -4652,10 +4650,6 @@ int sched_fork(unsigned long clone_flags
 	RB_CLEAR_NODE(&p->pushable_dl_tasks);
 #endif
 	return 0;
-
-out_cancel:
-	scx_cancel_fork(p);
-	return ret;
 }
 
 int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs)