From b6009b69e69c952a3a9d232f97b5985d62b09bcc Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 29 Sep 2021 11:37:32 +0200
Subject: [PATCH] sched: Remove pointless preemption disable in
sched_submit_work()
References: bsc#1189998 (PREEMPT_RT prerequisite backports)
Patch-mainline: v5.16-rc1
Git-commit: b945efcdd07d86cece1cce68503aae91f107eacb
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
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
kernel/sched/core.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1d0953ccddb7..f1819eb2376e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6066,20 +6066,14 @@ 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))