linux-kernel - Re: [patch 37/39] PCI/MSI: Remove redundant msi

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Date:   Wed, 16 Nov 2022 10:34:17 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ashok Raj <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
        Allen Hubbe <allenbh@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linuxppc-dev@...ts.ozlabs.org,
        "Ahmed S. Darwish" <darwi@...utronix.de>,
        Reinette Chatre <reinette.chatre@...el.com>
Subject: Re: [patch 37/39] PCI/MSI: Remove redundant msi_check() callback

On Fri, Nov 11, 2022 at 02:55:14PM +0100, Thomas Gleixner wrote:
> All these sanity checks are now done _before_ any allocation work
> happens. No point in doing it twice.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

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

> ---
>  drivers/pci/msi/irqdomain.c |   48 --------------------------------------------
>  1 file changed, 48 deletions(-)
> 
> --- a/drivers/pci/msi/irqdomain.c
> +++ b/drivers/pci/msi/irqdomain.c
> @@ -64,51 +64,6 @@ static irq_hw_number_t pci_msi_domain_ca
>  		(pci_domain_nr(dev->bus) & 0xFFFFFFFF) << 27;
>  }
>  
> -static inline bool pci_msi_desc_is_multi_msi(struct msi_desc *desc)
> -{
> -	return !desc->pci.msi_attrib.is_msix && desc->nvec_used > 1;
> -}
> -
> -/**
> - * pci_msi_domain_check_cap - Verify that @domain supports the capabilities
> - *			      for @dev
> - * @domain:	The interrupt domain to check
> - * @info:	The domain info for verification
> - * @dev:	The device to check
> - *
> - * Returns:
> - *  0 if the functionality is supported
> - *  1 if Multi MSI is requested, but the domain does not support it
> - *  -ENOTSUPP otherwise
> - */
> -static int pci_msi_domain_check_cap(struct irq_domain *domain,
> -				    struct msi_domain_info *info,
> -				    struct device *dev)
> -{
> -	struct msi_desc *desc = msi_first_desc(dev, MSI_DESC_ALL);
> -
> -	/* Special handling to support __pci_enable_msi_range() */
> -	if (pci_msi_desc_is_multi_msi(desc) &&
> -	    !(info->flags & MSI_FLAG_MULTI_PCI_MSI))
> -		return 1;
> -
> -	if (desc->pci.msi_attrib.is_msix) {
> -		if (!(info->flags & MSI_FLAG_PCI_MSIX))
> -			return -ENOTSUPP;
> -
> -		if (info->flags & MSI_FLAG_MSIX_CONTIGUOUS) {
> -			unsigned int idx = 0;
> -
> -			/* Check for gaps in the entry indices */
> -			msi_for_each_desc(desc, dev, MSI_DESC_ALL) {
> -				if (desc->msi_index != idx++)
> -					return -ENOTSUPP;
> -			}
> -		}
> -	}
> -	return 0;
> -}
> -
>  static void pci_msi_domain_set_desc(msi_alloc_info_t *arg,
>  				    struct msi_desc *desc)
>  {
> @@ -118,7 +73,6 @@ static void pci_msi_domain_set_desc(msi_
>  
>  static struct msi_domain_ops pci_msi_domain_ops_default = {
>  	.set_desc	= pci_msi_domain_set_desc,
> -	.msi_check	= pci_msi_domain_check_cap,
>  };
>  
>  static void pci_msi_domain_update_dom_ops(struct msi_domain_info *info)
> @@ -130,8 +84,6 @@ static void pci_msi_domain_update_dom_op
>  	} else {
>  		if (ops->set_desc == NULL)
>  			ops->set_desc = pci_msi_domain_set_desc;
> -		if (ops->msi_check == NULL)
> -			ops->msi_check = pci_msi_domain_check_cap;
>  	}
>  }
>  
>