Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Thomas Gleixner <tglx@linutronix.de>
To:     paulmck@kernel.org, linux-kernel@vger.kernel.org,
        rcu@vger.kernel.org
Cc:     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}()
In-Reply-To: <20200611235305.GA32342@paulmck-ThinkPad-P72>
References: <20200611235305.GA32342@paulmck-ThinkPad-P72>
Date:   Fri, 12 Jun 2020 11:27:21 +0200
Message-ID: <87ftb0d47a.fsf@nanos.tec.linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

"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. :)

Thanks,

        tglx