linux-kernel - Re: [PATCH v2 1/2] genirq: Retain depth for managed IRQs across CPU hotplug

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Message-ID: <87qzzqojpt.ffs@tglx>
Date: Wed, 11 Jun 2025 08:50:22 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Brian Norris <briannorris@...omium.org>, Aleksandrs Vinarskis
 <alex.vinarskis@...il.com>
Cc: Tsai Sung-Fu <danielsftsai@...gle.com>, Douglas Anderson
 <dianders@...omium.org>, linux-kernel@...r.kernel.org, Johan Hovold
 <johan@...nel.org>
Subject: Re: [PATCH v2 1/2] genirq: Retain depth for managed IRQs across CPU
 hotplug

On Tue, Jun 10 2025 at 13:07, Brian Norris wrote:
> On Mon, Jun 09, 2025 at 08:19:58PM +0200, Aleksandrs Vinarskis wrote:
>  
>  void irq_startup_managed(struct irq_desc *desc)
>  {
> +	struct irq_data *d = irq_desc_get_irq_data(desc);
> +
>  	/*
>  	 * Only start it up when the disable depth is 1, so that a disable,
>  	 * hotunplug, hotplug sequence does not end up enabling it during
>  	 * hotplug unconditionally.
>  	 */
>  	desc->depth--;
> +	irqd_clr_managed_shutdown(d);

If depth > 0, then it's still shutdown and the subsequent enable
operation which brings it down to 0 will take care of it. So what are
you trying to solve here?

>  	if (!desc->depth)
>  		irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
>  }
> diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
> index f07529ae4895..755346ea9819 100644
> --- a/kernel/irq/cpuhotplug.c
> +++ b/kernel/irq/cpuhotplug.c
> @@ -210,13 +210,6 @@ static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
>  	    !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
>  		return;
>  
> -	/*
> -	 * Don't restore suspended interrupts here when a system comes back
> -	 * from S3. They are reenabled via resume_device_irqs().
> -	 */
> -	if (desc->istate & IRQS_SUSPENDED)
> -		return;
> -

Huch? Care to read:

a60dd06af674 ("genirq/cpuhotplug: Skip suspended interrupts when restoring affinity")

Thanks,

        tglx