linux-kernel - Re: [patch V2 04/46] genirq/chip: Use the first chip in irq_chip_compose_msi

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Date:   Wed, 26 Aug 2020 22:32:02 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org, linux-hyperv@...r.kernel.org,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Jon Derrick <jonathan.derrick@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Wei Liu <wei.liu@...nel.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Steve Wahl <steve.wahl@....com>,
        Dimitri Sivanich <sivanich@....com>,
        Russ Anderson <rja@....com>, linux-pci@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        xen-devel@...ts.xenproject.org, Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Megha Dey <megha.dey@...el.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jacob Pan <jacob.jun.pan@...el.com>,
        Baolu Lu <baolu.lu@...el.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [patch V2 04/46] genirq/chip: Use the first chip in irq_chip_compose_msi_msg()

On Wed, 26 Aug 2020 22:19:56 +0100,
Thomas Gleixner <tglx@...utronix.de> wrote:
> 
> On Wed, Aug 26 2020 at 20:50, Marc Zyngier wrote:
> > On Wed, 26 Aug 2020 12:16:32 +0100,
> > Thomas Gleixner <tglx@...utronix.de> wrote:
> >> ---
> >> V2: New patch. Note, that this might break other stuff which relies on the
> >>     current behaviour, but the hierarchy composition of DT based chips is
> >>     really hard to follow.
> >

[...]

> What about the below?
> 
> Thanks,
> 
>         tglx
> ---
> --- a/kernel/irq/internals.h
> +++ b/kernel/irq/internals.h
> @@ -473,6 +473,15 @@ static inline void irq_domain_deactivate
>  }
>  #endif
>  
> +static inline struct irq_data *irqd_get_parent_data(struct irq_data *irqd)
> +{
> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
> +	return irqd->parent_data;
> +#else
> +	return NULL;
> +#endif
> +}
> +

We obviously should have had this forever.

>  #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
>  #include <linux/debugfs.h>
>  
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -1541,18 +1541,17 @@ EXPORT_SYMBOL_GPL(irq_chip_release_resou
>   */
>  int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
>  {
> -	struct irq_data *pos = NULL;
> +	struct irq_data *pos;
>  
> -#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
> -	for (; data; data = data->parent_data)
> -#endif
> +	for (pos = NULL; !pos && data; data = irqd_get_parent_data(data)) {
>  		if (data->chip && data->chip->irq_compose_msi_msg)
>  			pos = data;
> +	}
> +
>  	if (!pos)
>  		return -ENOSYS;
>  
>  	pos->chip->irq_compose_msi_msg(pos, msg);
> -
>  	return 0;
>  }

Perfect, ship it! ;-)

	M.

-- 
Without deviation from the norm, progress is not possible.