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SubjectRe: [PATCH v4 3/5] irqchip: sifive-plic: Add warning in plic_init() if handler already present
On Thu, Dec 27, 2018 at 04:48:19PM +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@brainfault.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
> 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 01bbbbffbcae..b9a0bcefe426 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -229,6 +229,11 @@ 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 already present for context %d.\n", i);
> + continue;
> + }
> +

Just use WARN_ON_ONCE?

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