linux-kernel - sched: Remove pointless preemption disable in sched_submit

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Message-ID: <87sfxoai2l.ffs@tglx>
Date:   Tue, 28 Sep 2021 16:30:26 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, Peter Oskolkov <posk@...k.io>,
        Tejun Heo <tj@...nel.org>, Jens Axboe <axboe@...nel.dk>
Subject: 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.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/sched/core.c |    2 --
 1 file changed, 2 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6327,12 +6327,10 @@ static inline void sched_submit_work(str
 	 * requires it.
 	 */
 	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))