On Thu, Feb 18, 2021 at 11:04:00AM +0800, Lai Jiangshan wrote: > +CC Paul > > > On Wed, Feb 17, 2021 at 7:58 PM <qiang.zh...@windriver.com> wrote: > > > > From: Zqiang <qiang.zh...@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 the rcu_read_lock() is removed, should there be a comment saying that it interacts with synchronize_rcu()? Just in case one of the real-time guys figures out a way to get the job done without disabling preemption... Thanx, Paul > 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.zh...@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 > >