Re: [PATCH v3 4/6] irqchip: sifive-plic: Add warning in plic_init() if handler already present

[Christoph Hellwig]

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@xxxxxxxxxxxxxx>
> ---
>  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@xxxxxx>