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

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Date:   Sun, 27 Dec 2020 11:20:49 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Karthikeyan Mitran <m.karthikeyan@...iveil.co.in>,
        Peter Zijlstra <peterz@...radead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        dri-devel@...ts.freedesktop.org,
        Chris Wilson <chris@...is-wilson.co.uk>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org,
        Will Deacon <will@...nel.org>,
        Michal Simek <michal.simek@...inx.com>,
        linux-s390@...r.kernel.org,
        afzal mohammed <afzal.mohd.ma@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Dave Jiang <dave.jiang@...el.com>,
        xen-devel@...ts.xenproject.org, Leon Romanovsky <leon@...nel.org>,
        linux-rdma@...r.kernel.org, Marc Zyngier <maz@...nel.org>,
        Helge Deller <deller@....de>,
        Russell King <linux@...linux.org.uk>,
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        David Airlie <airlied@...ux.ie>, linux-gpio@...r.kernel.org,
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        linux-ntb@...glegroups.com, intel-gfx@...ts.freedesktop.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [patch 02/30] genirq: Move status flag checks to core

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 <tglx@...utronix.de>

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;
> +}