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sched: Remove pointless preemption disable in sched_submit_work()

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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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lkml.kernel.org/r/8735pnafj7.ffs@tglx
This commit is contained in:
Thomas Gleixner 2021-09-29 11:37:32 +02:00 • committed by Peter Zijlstra
parent 670721c7bd
commit b945efcdd0
1 changed files with 2 additions and 8 deletions
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10
kernel/sched/core.c
View file

@ -6251,20 +6251,14 @@ static inline void sched_submit_work(struct task_struct *tsk)
task_flags = tsk->flags; task_flags = tsk->flags;
/* /*
* If a worker went to sleep, notify and ask workqueue whether * If a worker goes to sleep, notify and ask workqueue whether it
* it wants to wake up a task to maintain concurrency. * 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 (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) { if (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
preempt_disable();
if (task_flags & PF_WQ_WORKER) if (task_flags & PF_WQ_WORKER)
wq_worker_sleeping(tsk); wq_worker_sleeping(tsk);
else else
io_wq_worker_sleeping(tsk); io_wq_worker_sleeping(tsk);
preempt_enable_no_resched();
} }
if (tsk_is_pi_blocked(tsk)) if (tsk_is_pi_blocked(tsk))