linux-kernel - Re: [PATCH v3 4/6] irqchip: sifive-plic: Add warning in plic

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Message-ID: <20181217182812.GD7086@infradead.org>
Date:   Mon, 17 Dec 2018 10:28:12 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Anup Patel <anup@...infault.org>
Cc:     Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Christoph Hellwig <hch@...radead.org>,
        Atish Patra <atish.patra@....com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/6] irqchip: sifive-plic: Add warning in plic_init()
 if handler already present

On Fri, Nov 30, 2018 at 01:32:05PM +0530, Anup Patel wrote:
> We have two enteries (one for M-mode and another for S-mode) in the
> interrupts-extended DT property of PLIC DT node for each HART. It is
> expected that firmware/bootloader will set M-mode HWIRQ line of each
> HART to 0xffffffff (i.e. -1) in interrupts-extended DT property
> because Linux runs in S-mode only.
> 
> If firmware/bootloader is buggy then it will not correctly update
> interrupts-extended DT property which might result in a plic_handler
> configured twice. This patch adds a warning in plic_init() if a
> plic_handler is already marked present. This warning provides us
> a hint about incorrectly updated interrupts-extended DT property.
> 
> Signed-off-by: Anup Patel <anup@...infault.org>
> ---
>  drivers/irqchip/irq-sifive-plic.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index d4433399eb89..3d4f205f8abe 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -234,6 +234,11 @@ static int __init plic_init(struct device_node *node,
>  
>  		cpu = riscv_hartid_to_cpuid(hartid);
>  		handler = per_cpu_ptr(&plic_handlers, cpu);
> +		if (handler->present) {
> +			pr_warn("handler not available for context %d.\n", i);
> +			continue;
> +		}

Shouldn't this be something like "handler already present.."

Otherwise this looks fine:

Reviewed-by: Christoph Hellwig <hch@....de>