Commit b945efcd authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

sched: Remove pointless preemption disable in sched_submit_work() 



Neither wq_worker_sleeping() nor io_wq_worker_sleeping() require to be invoked
with preemption disabled:

  - The worker flag checks operations only need to be serialized against
    the worker thread itself.

  - The accounting and worker pool operations are serialized with locks.

which means that disabling preemption has neither a reason nor a
value. Remove it and update the stale comment.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarLai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Link: https://lkml.kernel.org/r/8735pnafj7.ffs@tglx
parent 670721c7

kernel/sched/core.c

+2 −8
Original line number Diff line number Diff line
@@ -6251,20 +6251,14 @@ static inline void sched_submit_work(struct task_struct *tsk) 


	task_flags = tsk->flags;

	/*

	 * If a worker went to sleep, notify and ask workqueue whether

	 * it wants to wake up a task to maintain concurrency.

	 * As this function is called inside the schedule() context,

	 * we disable preemption to avoid it calling schedule() again

	 * in the possible wakeup of a kworker and because wq_worker_sleeping()

	 * requires it.

	 * If a worker goes to sleep, notify and ask workqueue whether it

	 * wants to wake up a task to maintain concurrency.

	 */

	if (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) {

		preempt_disable();

		if (task_flags & PF_WQ_WORKER)

			wq_worker_sleeping(tsk);

		else

			io_wq_worker_sleeping(tsk);

		preempt_enable_no_resched();

	}



	if (tsk_is_pi_blocked(tsk))