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From: Thomas Gleixner <tglx@linutronix.de>
To: paulmck@kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>,
	rcu@vger.kernel.org, Andrew Lutomirski <luto@kernel.org>,
	X86 ML <x86@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH x86/entry: Force rcu_irq_enter() when in idle task
Date: Fri, 12 Jun 2020 21:25:20 +0200	[thread overview]
Message-ID: <87r1ukxf1b.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200612191921.GA18255@paulmck-ThinkPad-P72>

"Paul E. McKenney" <paulmck@kernel.org> writes:
> On Fri, Jun 12, 2020 at 10:49:53AM -0700, Paul E. McKenney wrote:
>> I will therefore address this issue in a follow-on patch.
>
> I should add that -your- patch from yesterday did -not- cause this
> problem, in case that is of interest.

So I still can add it back and amend the changelog and comment:

Change the condition from !rcu_is_watching() to is_idle_task(current) ||
rcu_is_watching() which enforces that interrupts in the idle task
unconditionally invoke rcu_irq_enter() independent of the RCU state. For
most scenarios is_idle_task() would be sufficient but Task RCU needs it
according to Paul.

Thanks,

        tglx

  reply	other threads:[~2020-06-12 19:25 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 [this message]
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

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