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sched_ext: Use SCX_TASK_READY test instead of tryget_task_struct() during class switch

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ddf7233fca ("sched/ext: Fix invalid task state transitions on class
switch") added tryget_task_struct() test during scx_enable()'s class
switching loop. The reason for the addition was to avoid enabling tasks which
skipped prep in the previous loop due to being dead.

While tryget_task_struct() does work for this purpose as tasks that fail
tryget always will fail it, it's a bit roundabout. A more direct way is
testing whether the task is in READY state. Switch to testing SCX_TASK_READY
directly.

Cc: Andrea Righi <arighi@nvidia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2025-10-28 11:38:34 -10:00
parent dcb938c453
commit b7d4b28db7
1 changed files with 1 additions and 3 deletions
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4
kernel/sched/ext.c
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@ -4753,7 +4753,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link)
const struct sched_class *new_class =
__setscheduler_class(p->policy, p->prio);
if (!tryget_task_struct(p))
if (scx_get_task_state(p) != SCX_TASK_READY)
continue;
if (old_class != new_class)
@ -4763,8 +4763,6 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link)
p->scx.slice = SCX_SLICE_DFL;
p->sched_class = new_class;
}
put_task_struct(p);
}
scx_task_iter_stop(&sti);
percpu_up_write(&scx_fork_rwsem);