Subject: Re: [patch 02/30] genirq: Move status flag checks to core

From: Guenter Roeck <[email-masked]>
Date: Sun, 27 Dec 2020 11:20:49 -0800

On Thu, Dec 10, 2020 at 08:25:38PM +0100, Thomas Gleixner wrote:
> These checks are used by modules and prevent the removal of the export of
> irq_to_desc(). Move the accessor into the core.
> 
> Signed-off-by: Thomas Gleixner <[email-masked]>

Yes, but that means that irq_check_status_bit() may be called from modules,
but it is not exported, resulting in build errors such as the following.

arm64:allmodconfig:

ERROR: modpost: "irq_check_status_bit" [drivers/perf/arm_spe_pmu.ko] undefined!

Guenter

> ---
>  include/linux/irqdesc.h |   17 +++++------------
>  kernel/irq/manage.c     |   17 +++++++++++++++++
>  2 files changed, 22 insertions(+), 12 deletions(-)
> 
> --- a/include/linux/irqdesc.h
> +++ b/include/linux/irqdesc.h
> @@ -223,28 +223,21 @@ irq_set_chip_handler_name_locked(struct
>  	data->chip = chip;
>  }
>  
> +bool irq_check_status_bit(unsigned int irq, unsigned int bitmask);
> +
>  static inline bool irq_balancing_disabled(unsigned int irq)
>  {
> -	struct irq_desc *desc;
> -
> -	desc = irq_to_desc(irq);
> -	return desc->status_use_accessors & IRQ_NO_BALANCING_MASK;
> +	return irq_check_status_bit(irq, IRQ_NO_BALANCING_MASK);
>  }
>  
>  static inline bool irq_is_percpu(unsigned int irq)
>  {
> -	struct irq_desc *desc;
> -
> -	desc = irq_to_desc(irq);
> -	return desc->status_use_accessors & IRQ_PER_CPU;
> +	return irq_check_status_bit(irq, IRQ_PER_CPU);
>  }
>  
>  static inline bool irq_is_percpu_devid(unsigned int irq)
>  {
> -	struct irq_desc *desc;
> -
> -	desc = irq_to_desc(irq);
> -	return desc->status_use_accessors & IRQ_PER_CPU_DEVID;
> +	return irq_check_status_bit(irq, IRQ_PER_CPU_DEVID);
>  }
>  
>  static inline void
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -2769,3 +2769,23 @@ bool irq_has_action(unsigned int irq)
>  	return res;
>  }
>  EXPORT_SYMBOL_GPL(irq_has_action);
> +
> +/**
> + * irq_check_status_bit - Check whether bits in the irq descriptor status are set
> + * @irq:	The linux irq number
> + * @bitmask:	The bitmask to evaluate
> + *
> + * Returns: True if one of the bits in @bitmask is set
> + */
> +bool irq_check_status_bit(unsigned int irq, unsigned int bitmask)
> +{
> +	struct irq_desc *desc;
> +	bool res = false;
> +
> +	rcu_read_lock();
> +	desc = irq_to_desc(irq);
> +	if (desc)
> +		res = !!(desc->status_use_accessors & bitmask);
> +	rcu_read_unlock();
> +	return res;
> +}