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Date:   Thu, 3 Dec 2020 14:03:20 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Valentin Schneider <valentin.schneider@arm.com>
Cc:     Marc Zyngier <maz@kernel.org>,
        LAK <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mark Rutland <mark.rutland@arm.com>,
        Russell King <linux@arm.linux.org.uk>,
        Android Kernel Team <kernel-team@android.com>
Subject: Re: [PATCH v2 2/6] genirq: Allow an interrupt to be marked as 'raw'
Message-ID: <20201203130320.GQ3021@hirez.programming.kicks-ass.net>
References: <20201124141449.572446-1-maz@kernel.org>
 <20201124141449.572446-3-maz@kernel.org>
 <jhj7dq8ugli.mognet@arm.com>
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On Thu, Nov 26, 2020 at 06:18:33PM +0000, Valentin Schneider wrote:
> If I got the RCU bits right from what Thomas mentioned in
> 
>   https://lore.kernel.org/r/87ft5q18qs.fsf@nanos.tec.linutronix.de
>   https://lore.kernel.org/r/87lfewnmdz.fsf@nanos.tec.linutronix.de
> 
> then we're still missing something to notify RCU in the case the IRQ hits
> the idle task. All I see on our entry path is
> 
>   trace_hardirqs_off();
>   ...
>   irq_handler()
>     handle_domain_irq();
>   ...
>   trace_hardirqs_on();
> 
> so we do currently rely on handle_domain_irq()'s irq_enter() + irq_exit()
> for that. rcu_irq_enter() says CONFIG_RCU_EQS_DEBUG=y can detect missing
> bits, but I don't get any warnings with your series on my Juno.

The scheduler IPI really doesn't need RCU either ;-)