Commit b7d4b28d authored by Tejun Heo's avatar Tejun Heo
Browse files

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



ddf7233f ("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: default avatarAndrea Righi <arighi@nvidia.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent dcb938c4

kernel/sched/ext.c

+1 −3
Original line number Diff line number Diff line
@@ -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);