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sched_ext: Exit early on hotplug events during attach 

There is no need to complete the entire scx initialization if a
scheduler is failing to be attached due to a hotplug event.

Exit early to avoid unnecessary work and simplify the attach flow.

Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Andrea Righi 2025-09-04 07:57:16 +02:00 committed by Tejun Heo
parent 14c1da3895
commit 0128c85051
1 changed files with 9 additions and 2 deletions
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11
kernel/sched/ext.c
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@ -4513,7 +4513,7 @@ static struct scx_sched *scx_alloc_and_add_sched(struct sched_ext_ops *ops)
return ERR_PTR(ret); return ERR_PTR(ret);
} }
static void check_hotplug_seq(struct scx_sched *sch, static int check_hotplug_seq(struct scx_sched *sch,
const struct sched_ext_ops *ops) const struct sched_ext_ops *ops)
{ {
unsigned long long global_hotplug_seq; unsigned long long global_hotplug_seq;
@ -4530,8 +4530,11 @@ static void check_hotplug_seq(struct scx_sched *sch,
SCX_ECODE_ACT_RESTART | SCX_ECODE_RSN_HOTPLUG, SCX_ECODE_ACT_RESTART | SCX_ECODE_RSN_HOTPLUG,
"expected hotplug seq %llu did not match actual %llu", "expected hotplug seq %llu did not match actual %llu",
ops->hotplug_seq, global_hotplug_seq); ops->hotplug_seq, global_hotplug_seq);
return -EBUSY;
} }
} }
return 0;
} }
static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops) static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops)
@ -4633,7 +4636,11 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link)
if (((void (**)(void))ops)[i]) if (((void (**)(void))ops)[i])
set_bit(i, sch->has_op); set_bit(i, sch->has_op);
check_hotplug_seq(sch, ops); ret = check_hotplug_seq(sch, ops);
if (ret) {
cpus_read_unlock();
goto err_disable;
}
scx_idle_update_selcpu_topology(ops); scx_idle_update_selcpu_topology(ops);
cpus_read_unlock(); cpus_read_unlock();