linux-kernel - Re: [RESEND 1/1] gic: its: Make sure a LPI is discarded before free.

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Date:   Wed, 9 Jan 2019 07:43:24 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Zhao Yuanyuan <yuanyuan.zhao@...-semitech.com>
Cc:     <tglx@...utronix.de>, <jason@...edaemon.net>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <yu.zheng@...-semitech.com>, <dongsheng.wang@...-semitech.com>
Subject: Re: [RESEND 1/1] gic: its: Make sure a LPI is discarded before
 free.

On Wed, 9 Jan 2019 11:53:27 +0800
Zhao Yuanyuan <yuanyuan.zhao@...-semitech.com> wrote:

Hi Zhao,

> Its device will be removed after all events be freed.
> Undisarded events can lead to unpredictable behaviar.
> 
> Signed-off-by: Zhao Yuanyuan <yuanyuan.zhao@...-semitech.com>
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index db20e99..4fee008 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -2572,6 +2572,10 @@ static void its_irq_domain_free(struct irq_domain *domain, unsigned int virq,
>  								virq + i);
>  		u32 event = its_get_event_id(data);
>  
> +		/* Discard irq before free */
> +		if (irqd_is_activated(d))
> +			its_send_discard(its_dev, event);
> +
>  		/* Mark interrupt index as unused */
>  		clear_bit(event, its_dev->event_map.lpi_map);
>  

But we already do send a discard on deactivate, which logically happens
before we free the domain. So what are you fixing here?

Thanks,

	M.
-- 
Without deviation from the norm, progress is not possible.