From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: Scott Wood <swood@redhat.com>,
linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
"Paul E . McKenney" <paulmck@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Clark Williams <williams@redhat.com>
Subject: Re: [PATCH RT v2 2/3] sched: migrate_enable: Use sleeping_lock to indicate involuntary sleep
Date: Mon, 26 Aug 2019 17:25:23 +0200 [thread overview]
Message-ID: <20190826152523.dcjbsgyyir4zjdol@linutronix.de> (raw)
In-Reply-To: <20190824031014.GB2731@google.com>
On 2019-08-23 23:10:14 [-0400], Joel Fernandes wrote:
> On Fri, Aug 23, 2019 at 02:28:46PM -0500, Scott Wood wrote:
> > On Fri, 2019-08-23 at 18:20 +0200, Sebastian Andrzej Siewior wrote:
> > >
> > > this looks like an ugly hack. This sleeping_lock_inc() is used where we
> > > actually hold a sleeping lock and schedule() which is okay. But this
> > > would mean we hold a RCU lock and schedule() anyway. Is that okay?
> >
> > Perhaps the name should be changed, but the concept is the same -- RT-
> > specific sleeping which should be considered involuntary for the purpose of
> > debug checks. Voluntary sleeping is not allowed in an RCU critical section
> > because it will break the critical section on certain flavors of RCU, but
> > that doesn't apply to the flavor used on RT. Sleeping for a long time in an
> > RCU critical section would also be a bad thing, but that also doesn't apply
> > here.
>
> I think the name should definitely be changed. At best, it is super confusing to
> call it "sleeping_lock" for this scenario. In fact here, you are not even
> blocking on a lock.
>
> Maybe "sleeping_allowed" or some such.
The mechanism that is used here may change in future. I just wanted to
make sure that from RCU's side it is okay to schedule here.
> thanks,
>
> - Joel
Sebastian
next prev parent reply other threads:[~2019-08-26 15:25 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 23:19 [PATCH RT v2 0/3] RCU fixes Scott Wood
2019-08-21 23:19 ` [PATCH RT v2 1/3] rcu: Acquire RCU lock when disabling BHs Scott Wood
2019-08-21 23:33 ` Paul E. McKenney
2019-08-22 13:39 ` Joel Fernandes
2019-08-22 15:27 ` Paul E. McKenney
2019-08-23 1:50 ` Joel Fernandes
2019-08-23 2:11 ` Paul E. McKenney
2019-08-23 3:23 ` Scott Wood
2019-08-23 12:30 ` Paul E. McKenney
2019-08-23 16:17 ` Sebastian Andrzej Siewior
2019-08-23 19:46 ` Scott Wood
2019-08-26 15:59 ` Sebastian Andrzej Siewior
2019-08-26 23:21 ` Scott Wood
2019-08-23 2:36 ` Scott Wood
2019-08-23 2:54 ` Paul E. McKenney
2019-08-21 23:19 ` [PATCH RT v2 2/3] sched: migrate_enable: Use sleeping_lock to indicate involuntary sleep Scott Wood
2019-08-21 23:35 ` Paul E. McKenney
2019-08-23 1:21 ` Scott Wood
2019-08-23 16:20 ` Sebastian Andrzej Siewior
2019-08-23 19:28 ` Scott Wood
2019-08-24 3:10 ` Joel Fernandes
2019-08-26 15:25 ` Sebastian Andrzej Siewior [this message]
2019-08-26 16:29 ` Paul E. McKenney
2019-08-26 17:49 ` Scott Wood
2019-08-26 18:12 ` Paul E. McKenney
2019-08-27 9:23 ` Sebastian Andrzej Siewior
2019-08-27 13:08 ` Joel Fernandes
2019-08-27 15:58 ` Paul E. McKenney
2019-08-27 16:06 ` Joel Fernandes
2019-08-27 15:53 ` Paul E. McKenney
2019-08-28 9:27 ` Sebastian Andrzej Siewior
2019-08-28 12:54 ` Paul E. McKenney
2019-08-28 13:14 ` Sebastian Andrzej Siewior
2019-08-28 13:59 ` Joel Fernandes
2019-08-28 15:51 ` Paul E. McKenney
2019-08-28 15:50 ` Paul E. McKenney
2019-08-21 23:19 ` [PATCH RT v2 3/3] rcu: Disable use_softirq on PREEMPT_RT Scott Wood
2019-08-21 23:40 ` Paul E. McKenney
2019-08-23 16:32 ` Sebastian Andrzej Siewior
2019-08-22 13:59 ` Joel Fernandes
2019-08-22 15:29 ` Paul E. McKenney
2019-08-22 19:31 ` Scott Wood
2019-08-23 0:52 ` Joel Fernandes
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