From: "Paul E. McKenney" <paulmck@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
luto@kernel.org, x86@kernel.org, frederic@kernel.org,
rostedt@goodmis.org, joel@joelfernandes.org,
mathieu.desnoyers@efficios.com, will@kernel.org,
peterz@infradead.org
Subject: Re: [PATCH RFC] x86/entry: Ask RCU if it needs rcu_irq_{enter,exit}()
Date: Fri, 12 Jun 2020 06:57:08 -0700 [thread overview]
Message-ID: <20200612135708.GJ4455@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <87ftb0d47a.fsf@nanos.tec.linutronix.de>
On Fri, Jun 12, 2020 at 11:27:21AM +0200, Thomas Gleixner wrote:
> "Paul E. McKenney" <paulmck@kernel.org> writes:
> > +static __always_inline bool rcu_needs_irq_enter(void)
> > +{
> > + return !IS_ENABLED(CONFIG_TINY_RCU) &&
> > + (context_tracking_enabled_cpu(smp_processor_id()) || is_idle_task(current));
>
> This reintroduces the #PF problem which started the whole conditional
> RCU entry discussion:
>
> https://lore.kernel.org/lkml/20200515235125.628629605@linutronix.de/
>
> and which made us all come to the conclusion that we can do it always
> conditional. No biscuit for you. :)
We can only be thankful that source-code control systems mean that my
coding session yesterday afternoon will have no permanent effect.
Let this be a lesson to all of you: Hacking RCU while sleep-deprived
is a really bad idea. ;-)
Thanx, Paul
prev parent reply other threads:[~2020-06-12 13:57 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 23:53 [PATCH RFC] x86/entry: Ask RCU if it needs rcu_irq_{enter,exit}() Paul E. McKenney
2020-06-11 23:54 ` Paul E. McKenney
2020-06-12 5:30 ` Andy Lutomirski
2020-06-12 12:40 ` Thomas Gleixner
2020-06-12 13:55 ` [PATCH x86/entry: Force rcu_irq_enter() when in idle task Thomas Gleixner
2020-06-12 14:26 ` Frederic Weisbecker
2020-06-12 14:47 ` Thomas Gleixner
2020-06-12 15:32 ` Andy Lutomirski
2020-06-12 17:49 ` Paul E. McKenney
2020-06-12 19:19 ` Paul E. McKenney
2020-06-12 19:25 ` Thomas Gleixner
2020-06-12 19:28 ` Andy Lutomirski
2020-06-12 19:34 ` Thomas Gleixner
2020-06-12 21:56 ` Paul E. McKenney
2020-06-12 19:50 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-06-15 20:16 ` [PATCH " Joel Fernandes
2020-06-16 8:40 ` Thomas Gleixner
2020-06-16 14:30 ` Joel Fernandes
2020-06-16 16:52 ` Andy Lutomirski
2020-06-12 9:27 ` [PATCH RFC] x86/entry: Ask RCU if it needs rcu_irq_{enter,exit}() Thomas Gleixner
2020-06-12 13:57 ` Paul E. McKenney [this message]
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