Messages in this thread | | | From | Lai Jiangshan <> | Date | Thu, 18 Feb 2021 11:04:00 +0800 | Subject | Re: [PATCH] workqueue: Remove rcu_read_lock/unlock() in workqueue_congested() |
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+CC Paul
On Wed, Feb 17, 2021 at 7:58 PM <qiang.zhang@windriver.com> wrote: > > From: Zqiang <qiang.zhang@windriver.com> > > The RCU read critical area already by preempt_disable/enable() > (equivalent to rcu_read_lock_sched/unlock_sched()) mark, so remove > rcu_read_lock/unlock().
I think we can leave it which acks like document, especially workqueue_congested() is not performance crucial. Either way is Ok for me.
If it needs to be changed, please also do the same for rcu_read_lock() in wq_watchdog_timer_fn().
And __queue_work() and try_to_grab_pending() also use local_irq_save() and rcu_read_lock() at the same time, but I don't know will these local_irq_save() be changed to raw_local_irq_save() in PREEMPT_RT.
> > Signed-off-by: Zqiang <qiang.zhang@windriver.com> > --- > kernel/workqueue.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index 0d150da252e8..c599835ad6c3 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -4540,7 +4540,6 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq) > struct pool_workqueue *pwq; > bool ret; > > - rcu_read_lock(); > preempt_disable(); > > if (cpu == WORK_CPU_UNBOUND) > @@ -4553,7 +4552,6 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq) > > ret = !list_empty(&pwq->delayed_works); > preempt_enable(); > - rcu_read_unlock(); > > return ret; > } > -- > 2.25.1 >
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