linux-kernel - Re: [patch V2 23/23] PCI/MSI: Move descriptor counting on allocation fail to the legacy code

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Date:   Tue, 7 Dec 2021 15:02:38 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Megha Dey <megha.dey@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-pci@...r.kernel.org,
        Cedric Le Goater <clg@...d.org>,
        Juergen Gross <jgross@...e.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linuxppc-dev@...ts.ozlabs.org,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-mips@...r.kernel.org, Kalle Valo <kvalo@...eaurora.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        sparclinux@...r.kernel.org, x86@...nel.org,
        xen-devel@...ts.xenproject.org, ath11k@...ts.infradead.org,
        Wei Liu <wei.liu@...nel.org>, linux-hyperv@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>
Subject: Re: [patch V2 23/23] PCI/MSI: Move descriptor counting on allocation
 fail to the legacy code

On Mon, Dec 06, 2021 at 11:28:00PM +0100, Thomas Gleixner wrote:
> The irqdomain code already returns the information. Move the loop to the
> legacy code.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Tested-by: Juergen Gross <jgross@...e.com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

> ---
>  drivers/pci/msi/legacy.c |   20 +++++++++++++++++++-
>  drivers/pci/msi/msi.c    |   19 +------------------
>  2 files changed, 20 insertions(+), 19 deletions(-)
> 
> --- a/drivers/pci/msi/legacy.c
> +++ b/drivers/pci/msi/legacy.c
> @@ -50,9 +50,27 @@ void __weak arch_teardown_msi_irqs(struc
>  	}
>  }
>  
> +static int pci_msi_setup_check_result(struct pci_dev *dev, int type, int ret)
> +{
> +	struct msi_desc *entry;
> +	int avail = 0;
> +
> +	if (type != PCI_CAP_ID_MSIX || ret >= 0)
> +		return ret;
> +
> +	/* Scan the MSI descriptors for successfully allocated ones. */
> +	for_each_pci_msi_entry(entry, dev) {
> +		if (entry->irq != 0)
> +			avail++;
> +	}
> +	return avail ? avail : ret;
> +}
> +
>  int pci_msi_legacy_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
>  {
> -	return arch_setup_msi_irqs(dev, nvec, type);
> +	int ret = arch_setup_msi_irqs(dev, nvec, type);
> +
> +	return pci_msi_setup_check_result(dev, type, ret);
>  }
>  
>  void pci_msi_legacy_teardown_msi_irqs(struct pci_dev *dev)
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -609,7 +609,7 @@ static int msix_capability_init(struct p
>  
>  	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
>  	if (ret)
> -		goto out_avail;
> +		goto out_free;
>  
>  	/* Check if all MSI entries honor device restrictions */
>  	ret = msi_verify_entries(dev);
> @@ -634,23 +634,6 @@ static int msix_capability_init(struct p
>  	pcibios_free_irq(dev);
>  	return 0;
>  
> -out_avail:
> -	if (ret < 0) {
> -		/*
> -		 * If we had some success, report the number of IRQs
> -		 * we succeeded in setting up.
> -		 */
> -		struct msi_desc *entry;
> -		int avail = 0;
> -
> -		for_each_pci_msi_entry(entry, dev) {
> -			if (entry->irq != 0)
> -				avail++;
> -		}
> -		if (avail != 0)
> -			ret = avail;
> -	}
> -
>  out_free:
>  	free_msi_irqs(dev);
>  
>