linux-kernel - Re: [PATCH] arm64: smp: Fix missing IPI statistics

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Date: Wed, 19 Jun 2024 14:32:59 +0100
From: Will Deacon <will@...nel.org>
To: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: catalin.marinas@....com, mark.rutland@....com, dianders@...omium.org,
	swboyd@...omium.org, sumit.garg@...aro.org, frederic@...nel.org,
	scott@...amperecomputing.com, misono.tomohiro@...itsu.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: smp: Fix missing IPI statistics

On Fri, Jun 07, 2024 at 03:47:16PM +0800, Jinjie Ruan wrote:
> commit 83cfac95c018 ("genirq: Allow interrupts to be excluded from
> /proc/interrupts") is to avoid IPIs appear twice in /proc/interrupts.
> But the commit 331a1b3a836c ("arm64: smp: Add arch support for backtrace
> using pseudo-NMI") and commit 2f5cd0c7ffde("arm64: kgdb: Implement
> kgdb_roundup_cpus() to enable pseudo-NMI roundup") set CPU_BACKTRACE and
> KGDB_ROUNDUP IPIs "IRQ_HIDDEN" flag but not show them in
> arch_show_interrupts(), which cause the interrupt kstat_irqs accounting
> is missing in display.
> 
> Fixes: 331a1b3a836c ("arm64: smp: Add arch support for backtrace using pseudo-NMI")
> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> ---
>  arch/arm64/kernel/smp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 31c8b3094dd7..7f9a5cf0f3b8 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -1039,7 +1039,8 @@ void __init set_smp_ipi_range(int ipi_base, int n)
>  		}
>  
>  		ipi_desc[i] = irq_to_desc(ipi_base + i);
> -		irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
> +		if (i < NR_IPI)
> +			irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
>  	}

Please can you show the contents of /proc/interrupts before and after
this patch and put that in the commit message? I'm not seeing how the
two new IPIs get picked up by arch_show_interrupts().

Thanks,

Will