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

Tejun Heo
2024-06-24T20:51:51Z

From: Tejun Heo <tj@kernel.org>

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@kernel.org>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Vernet <void@manifault.com>
---
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)